ritonavir (Rx)

Brand and Other Names:Norvir
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Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

capsule

  • 100mg

tablet

  • 100mg

oral solution

  • 80mg/mL

oral powder

  • 100mg/packet

HIV Infection

Not typically used as sole protease inhibitor (PI), but as pharmacokinetic enhancer of other PIs

Indicated in combination with other antiretroviral agents for the treatment of HIV-infection

300 mg PO q12hr intially; increase by 100 mg q12hr to 600 mg PO q12hr over 5 days as tolerated

Use as booster with another protease inhibitor: 100-400 mg PO qDay or divided q12hr

Hepatic Impairment

Monitor therapy carefully with moderate and severe hepatic impairment

Dosage Forms & Strengths

capsule

  • 100mg

tablet

  • 100mg

oral solution

  • 80mg/mL

oral powder

  • 100mg/packet

HIV Infection

Indicated in combination with other antiretroviral agents for the treatment of pediatric patients with HIV-1 infection

Not used as sole protease inhibitor (PI), but as pharmacokinetic enhancer of other PIs

Age <1 month: Safety and efficacy not established

Age ≥1 month: 250 mg/m² PO q12hr initially; increase by 50 mg/m² q2-3days to 350-400 mg/m² q12hr; not to exceed 600 mg q12hr  

Adolescents: 300 mg PO q12hr intially; increase by 100 mg q12hr to 600 mg PO q12hr over 5 days as tolerated

Oral solution

  • Do not administer to neonates before postmenstrual age of 44 weeks
  • Contains 43.2% alcohol and 26.57% propylene glycol; total amounts of alcohol and propylene glycol from all medicines that are to be given to pediatric patients aged 1-6 months should be taken into account in order to avoid toxicity from these excipients
  • Measure dose with calibrated oral syringe

Oral powder

  • Used only for dosing increments of 100 mg
  • Should not be used for doses <100-mg or for incremental doses between 100-mg intervals (use oral solution for these doses)
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Interactions

Interaction Checker

and ritonavir

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            Contraindicated (35)

            • alfuzosin

              ritonavir will increase the level or effect of alfuzosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

            • amiodarone

              ritonavir will increase the level or effect of amiodarone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

              amiodarone will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Contraindicated.

              ritonavir increases levels of amiodarone by decreasing metabolism. Contraindicated.

            • cobicistat

              cobicistat will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

            • cobimetinib

              ritonavir will increase the level or effect of cobimetinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Avoid coadministration with strong CYP3A4 inhibitors with (increases cobimetinib systemic exposure by 6.7-fold).

            • conivaptan

              ritonavir will increase the level or effect of conivaptan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Coadministration of conivaptan with strong CYP3A4 inhibitors is contraindicated.

            • dihydroergotamine

              ritonavir will increase the level or effect of dihydroergotamine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

            • dihydroergotamine intranasal

              ritonavir will increase the level or effect of dihydroergotamine intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

            • disulfiram

              disulfiram increases toxicity of ritonavir by aldehyde dehydrogenase inhibition. Contraindicated. Interaction only associated with oral solution, which contains 42% alcohol.

            • elagolix

              ritonavir will increase the level or effect of elagolix by Other (see comment). Contraindicated. Concomitant use of elagolix and strong OATP1B1 inhibitors is contraindicated.

            • eliglustat

              ritonavir will increase the level or effect of eliglustat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Strong CYP3A4 inhibitors are contraindicated with eliglustat poor or intermediate metabolizers; reduce eliglustat dose from 84 mg BID to 84 mg once daily in extensive metabolizers; eliglustat is contraindiated if strong or moderate CYP2D6 inhibitors are given concomitantly with strong or moderate CYP3A inhibitors

              ritonavir increases levels of eliglustat by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated. If coadministered with strong or moderate CYP2D6 inhibitors, reduce eliglustat dose from 84 mg BID to 84 mg once daily in extensive and intermediate metabolizers; eliglustat is contraindiated if strong or moderate CYP2D6 inhibitors are given concomitantly with strong or moderate CYP3A inhibitors.

            • elvitegravir/cobicistat/emtricitabine/tenofovir DF

              ritonavir, elvitegravir/cobicistat/emtricitabine/tenofovir DF. Other (see comment). Contraindicated. Comment: Elvitegravir/cobicistat/emtricitabine/tenofovir is a complete regimen for HIV and should not be administered with other antiretrovirals.

              ritonavir will increase the level or effect of elvitegravir/cobicistat/emtricitabine/tenofovir DF by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

            • enzalutamide

              ritonavir will increase the level or effect of enzalutamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

              enzalutamide will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

            • ergoloid mesylates

              ritonavir will increase the level or effect of ergoloid mesylates by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

            • ergonovine

              ritonavir will increase the level or effect of ergonovine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

            • finerenone

              ritonavir will increase the level or effect of finerenone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

            • flibanserin

              ritonavir will increase the level or effect of flibanserin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Coadministration of flibanserin with moderate or strong CYP3A4 inhibitors is contraindicated. Severe hypotension or syncope can occur.

            • irinotecan

              ritonavir will increase the level or effect of irinotecan by P-glycoprotein (MDR1) efflux transporter. Contraindicated.

            • irinotecan liposomal

              ritonavir will increase the level or effect of irinotecan liposomal by P-glycoprotein (MDR1) efflux transporter. Contraindicated.

            • ivabradine

              ritonavir will increase the level or effect of ivabradine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Coadministration of ivabradine with strong CYP3A4 inhibitors is contraindicated.

            • lomitapide

              ritonavir increases levels of lomitapide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Increases lomitapide levels several folds.

            • lonafarnib

              ritonavir will increase the level or effect of lonafarnib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Lonafarnib is a sensitive CYP3A4 substrate. Coadministration with strong or moderate CYP3A4 inhibitors is contraindicated.

            • lovastatin

              ritonavir will increase the level or effect of lovastatin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Strong CYP3A4 inhibitors increase systemic statin exposure and risk of myopathy, including rhabdomyolysis

              lovastatin will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Contraindicated.

            • lurasidone

              ritonavir will increase the level or effect of lurasidone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Coadministration of lurasidone and strong CYP3A4 inhibitors is contraindicated.

            • methylergonovine

              ritonavir will increase the level or effect of methylergonovine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

            • naloxegol

              ritonavir will increase the level or effect of naloxegol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Coadministration of naloxegol with strong CYP3A4 inhibitors can significantly increase naloxegol systemic exposure which may precipitate opioid withdrawal symptoms

            • pimozide

              ritonavir increases levels of pimozide by decreasing metabolism. Contraindicated. Risk of QT interval prolongation.

            • regorafenib

              ritonavir, regorafenib. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Strong CYP3A4 inhibitors increase regorafenib levels and decrease exposure of the active metabolites M-2 and M-5.

            • salmeterol

              ritonavir increases levels of salmeterol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Potential for increased toxicity.

            • simvastatin

              ritonavir will increase the level or effect of simvastatin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

              simvastatin will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Contraindicated.

              ritonavir increases toxicity of simvastatin by Other (see comment). Contraindicated. Comment: OATP1B1 inhibitors may increase risk of myopathy.

            • sofosbuvir/velpatasvir

              ritonavir will increase the level or effect of sofosbuvir/velpatasvir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

            • St John's Wort

              St John's Wort will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

            • tinidazole

              tinidazole increases toxicity of ritonavir by aldehyde dehydrogenase inhibition. Contraindicated. Interaction only associated with oral solution, which contains 42% alcohol.

            • venetoclax

              ritonavir will increase the level or effect of venetoclax by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Use of strong CYP3A4 inhibitors is contraindicated with venetoclax during the initial ramp-up dosing phase. If a strong CYP3A inhibitor must be used after the ramp-up phase, reduce the venetoclax dose by at least 75%.

            • voclosporin

              ritonavir will increase the level or effect of voclosporin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

            • voriconazole

              voriconazole will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

              ritonavir decreases levels of voriconazole by increasing metabolism. Contraindicated. Ritonavir 400 mg BID decreases voriconazole levels; lower ritonavir doses have unknown effect.

            Serious - Use Alternative (164)

            • abametapir

              abametapir will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. For 2 weeks after abametapir application, avoid taking drugs that are CYP3A4 substrates. If not feasible, avoid use of abametapir.

            • acalabrutinib

              ritonavir will increase the level or effect of acalabrutinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of acalabrutinib with strong CYP3A inhibitors. If a strong CYP3A inhibitor must be used short-term (eg, up to 7 days), temporarily interrupt treatment with acalabrutinib.

            • ado-trastuzumab emtansine

              ritonavir increases levels of ado-trastuzumab emtansine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. DM1, the cytotoxic component, is metabolized mainly by CYP3A4; strong CYP3A4 inhibitors may increase DM1 exposure and toxicity.

            • afatinib

              ritonavir increases levels of afatinib by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. Reduce afatinib daily dose by 10 mg if not tolerated when coadministered with P-gp inhibitors.

            • apalutamide

              apalutamide will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of apalutamide, a strong CYP3A4 inducer, with drugs that are CYP3A4 substrates can result in lower exposure to these medications. Avoid or substitute another drug for these medications when possible. Evaluate for loss of therapeutic effect if medication must be coadministered. Adjust dose according to prescribing information if needed.

            • apixaban

              ritonavir will increase the level or effect of apixaban by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If taking apixaban dose >2.5 mg BID, decrease dose by 50% if coadministered with strong dual inhibitors of CYP3A4 and P-gp; if currently taking apixaban 2.5 mg PO BID, avoid coadministration with strong dual inhibitors of CYP3A4 and P-gp

            • aprepitant

              ritonavir will increase the level or effect of aprepitant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • atorvastatin

              ritonavir increases toxicity of atorvastatin by Other (see comment). Avoid or Use Alternate Drug. Comment: OATP1B1 inhibitors may increase risk of myopathy.

            • avanafil

              ritonavir will increase the level or effect of avanafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. CYP3A4 inhibitors may reduce avanafil clearance increasing systemic exposure to avanafil; significantly increased levels may result in significant adverse events including severe hypotension, syncope, visual changes, and priapism. Coadministration with strong CYP3A4 is contraindicated.

            • avapritinib

              ritonavir will increase the level or effect of avapritinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of avapritinib with strong CYP3A4 inhibitors.

            • avatrombopag

              ritonavir will increase the level or effect of avatrombopag by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • axitinib

              ritonavir increases levels of axitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, reduce axitinib dose by 50%.

            • bedaquiline

              ritonavir will increase the level or effect of bedaquiline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of bedaquiline with strong CYP3A4 inhibitors for >14 consecutive days, unless the benefit of treatment outweighs the risk

            • bosentan

              bosentan will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. stop bosentan >36 hours prior to PI initiation and restart 10 days after PI initiation at 62.5 mg once daily or every other day.

            • bosutinib

              ritonavir increases levels of bosutinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Strong CYP3A4 inhibitors increases bosutinib plasma concentration ~5-fold.

              ritonavir increases levels of bosutinib by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug.

            • brigatinib

              ritonavir will increase the level or effect of brigatinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If concomitant use of a strong CYP3A inhibitor cannot be avoided, reduce the brigatinib once daily dose by about 50% (ie, from 180 mg to 90 mg, or from 90 mg to 60 mg). After discontinuation of a strong CYP3A inhibitor, resume the brigatinib dose that was tolerated prior to initiating the strong CYP3A inhibitor.

            • bromocriptine

              ritonavir will increase the level or effect of bromocriptine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • cabergoline

              ritonavir increases levels of cabergoline by decreasing metabolism. Contraindicated.

            • cabotegravir

              ritonavir, cabotegravir. Other (see comment). Avoid or Use Alternate Drug. Comment: Cabotegravir plus rilpivirine is a complete regimen. Coadministration with other antiretroviral medications for treating HIV-1 infection is not recommended.

            • cabozantinib

              ritonavir will increase the level or effect of cabozantinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of cabozantinib with strong CYP3A4 inhibitors. If a strong CYP3A4 inhibitor is required, decrease cabozantinib dose by 40 mg/day (Cometriq) or by 20 mg/day (Cabometyx). Resume previous dose 2-3 days after strong CYP3A4 inhibitor discontinued.

            • calcitriol

              ritonavir will increase the level or effect of calcitriol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • capmatinib

              ritonavir will increase the level or effect of capmatinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • carbamazepine

              carbamazepine will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • ceritinib

              ritonavir increases levels of ceritinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid if possible; if concomitant use is unavoidable, reduce ceritinib dose by ~33%; after discontinuation of strong CYP3A inhibitor, resume at previous dose.

            • chloramphenicol

              chloramphenicol will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • chlorpheniramine

              ritonavir will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • cimetidine

              cimetidine will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • clarithromycin

              clarithromycin will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • cobicistat

              ritonavir will increase the level or effect of cobicistat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

            • colchicine

              ritonavir will increase the level or effect of colchicine by Other (see comment). Avoid or Use Alternate Drug. Colchicine is a P-gp and CYP3A4 substrate. Avoid use with drugs that are both P-gp and strong CYP3A4 inhibitors. If coadministration is necessary, decrease colchicine dose or frequency as recommended in prescribing information. Use of any colchicine product in conjunction with strong CYP3A4 inhibitors is contraindicated in patients with renal or hepatic impairment.

            • copanlisib

              ritonavir will increase the level or effect of copanlisib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If concomitant use with strong CYP3A inhibitors cannot be avoided, reduce copanlisib dose to 45 mg.

            • cyclophosphamide

              ritonavir will increase the level or effect of cyclophosphamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • dabrafenib

              ritonavir increases levels of dabrafenib by decreasing metabolism. Avoid or Use Alternate Drug. Strong CYP2C8 inhibitors may increase dabrafenib levels.

              ritonavir increases levels of dabrafenib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

              dabrafenib will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • dacomitinib

              dacomitinib will increase the level or effect of ritonavir by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Avoid use with CYP2D6 substrates where minimal increases in concentration of the CYP2D6 substrate may lead to serious or life-threatening toxicities.

            • dantrolene

              ritonavir will increase the level or effect of dantrolene by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • darunavir

              ritonavir will increase the level or effect of darunavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • dasatinib

              ritonavir will increase the level or effect of dasatinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. May require decreased dasatinib dose or adjustment of dosing interval. Both ritonavir and dasatinib are CYP3A4 inhibitor, however, ritonavir is a strong CYP3A4 inhibitor and more likely to increase dasatinib levels and increase risk for toxicity including prolonged QT interval.

            • dronedarone

              ritonavir will increase the level or effect of dronedarone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

              dronedarone will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug.

            • edoxaban

              ritonavir will increase the level or effect of edoxaban by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. Dose adjustment may be required with strong P-gp inhibitors. DVT/PE treatment: Decrease dose to 30 mg PO once daily. NVAF: No dose reduction recommended

            • elagolix

              ritonavir will increase the level or effect of elagolix by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • elbasvir/grazoprevir

              ritonavir will increase the level or effect of elbasvir/grazoprevir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • eletriptan

              ritonavir increases levels of eletriptan by decreasing metabolism. Contraindicated. Separate by 72 hours.

            • eluxadoline

              ritonavir increases levels of eluxadoline by decreasing metabolism. Avoid or Use Alternate Drug. Decrease eluxadoline dose to 75 mg PO BID if coadministered with OATP1B1 inhibitors. .

            • encorafenib

              ritonavir will increase the level or effect of encorafenib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If concomitant use of a strong CYP3A4 inhibitor is unavoidable, reduce encorafenib dose to one-third of the dose (eg, reduce from 450 mg/day to 150 mg/day). After discontinuing the inhibitor for 3-5 elimination half-lives, resume previous encorafenib dose.

            • entrectinib

              ritonavir will increase the level or effect of entrectinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of strong CYP3A4 inhibitors with entrectinib, a CYP3A4 substrate. If coadministration unavoidable, reduce entrectinib dose to 100 mg/day for patients aged 12 y or older with BSA >1.50m2. Resume previous entrectinib dose after discontinuing strong CYP3A inhibitor for 3-5 elimination half-lives.

            • erdafitinib

              ritonavir will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

              erdafitinib will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

            • ergoloid mesylates

              ritonavir increases levels of ergoloid mesylates by decreasing metabolism. Contraindicated.

            • ergotamine

              ritonavir will increase the level or effect of ergotamine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

              ritonavir increases levels of ergotamine by decreasing metabolism. Contraindicated.

            • erythromycin base

              erythromycin base will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

              ritonavir will increase the level or effect of erythromycin base by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

            • erythromycin ethylsuccinate

              erythromycin ethylsuccinate will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

              ritonavir will increase the level or effect of erythromycin ethylsuccinate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

            • erythromycin lactobionate

              erythromycin lactobionate will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

              ritonavir will increase the level or effect of erythromycin lactobionate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

            • erythromycin stearate

              erythromycin stearate will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

              ritonavir will increase the level or effect of erythromycin stearate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

            • ethinylestradiol

              ritonavir, ethinylestradiol. Other (see comment). Avoid or Use Alternate Drug. Comment: Significant changes (increase or decrease) can occur in estrogen plasma levels. Efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended. .

              ritonavir will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • etravirine

              ritonavir, etravirine. Other (see comment). Contraindicated. Comment: Different preparations of ritonavir have varying effects on etravirine, due to alterations in metabolism. The following preparations are contraindicated with etravirine: ritonavir 600 mg bid; tipranavir/ritonavir; fosamprenavir/ritonavir; atazanavir/ritonavir. The following preparation should be co-admin. with caution: lopinavir/ritonavir. The following preparations need no dose adjustment: darunavir/ritonavir; saquinavir/ritonavir.

              etravirine will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • everolimus

              ritonavir will increase the level or effect of everolimus by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

              ritonavir will increase the level or effect of everolimus by P-glycoprotein (MDR1) efflux transporter. Contraindicated.

            • fedratinib

              ritonavir will increase the level or effect of fedratinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid fedratinib coadministration with strong CYP3A4 inhibitors, decrease fedratinib dose to 200 mg/day. If CYP3A4 inhibitor discontinued, increase fedratinib dose to 300 mg/day for 2 weeks, and then 400 mg/day thereafter as tolerated.

              ritonavir will increase the level or effect of fedratinib by Other (see comment). Avoid or Use Alternate Drug. Avoid coadministration of fedratinib (a CYP3A4 and CYP2C19 substrate) with dual CYP3A4 and CYP2C19 inhibitor. Effect of coadministration of a dual CYP3A4 and CYP2C19 inhibitor with fedratinib has not been studied.

            • felbamate

              ritonavir will increase the level or effect of felbamate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • fentanyl

              ritonavir will increase the level or effect of fentanyl by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of CYP3A4 inhibitors with fentanyl is necessary, monitor patients for respiratory depression and sedation at frequent intervals and consider fentanyl dose adjustments until stable drug effects are achieved.

            • fentanyl intranasal

              ritonavir will increase the level or effect of fentanyl intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of CYP3A4 inhibitors with fentanyl is necessary, monitor patients for respiratory depression and sedation at frequent intervals and consider fentanyl dose adjustments until stable drug effects are achieved.

            • fentanyl transdermal

              ritonavir will increase the level or effect of fentanyl transdermal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of CYP3A4 inhibitors with fentanyl is necessary, monitor patients for respiratory depression and sedation at frequent intervals and consider fentanyl dose adjustments until stable drug effects are achieved.

            • fentanyl transmucosal

              ritonavir will increase the level or effect of fentanyl transmucosal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of CYP3A4 inhibitors with fentanyl is necessary, monitor patients for respiratory depression and sedation at frequent intervals and consider fentanyl dose adjustments until stable drug effects are achieved.

            • fexinidazole

              ritonavir will decrease the level or effect of fexinidazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration, monitor fexinidazole for decreased efficacy owing to decreased plasma concentrations of active M1 and M2 metabolites.

            • flecainide

              ritonavir will increase the level or effect of flecainide by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated. Concurrent use of flecainide and ritonavir is contraindicated.

              ritonavir increases levels of flecainide by decreasing metabolism. Contraindicated.

            • fluticasone intranasal

              ritonavir will increase the level or effect of fluticasone intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Strong CYP3A4 inhibitors may increase systemic corticosteroid adverse effects; monitor for signs/symptoms of high corticosteroid concentrations including Cushing type signs/symptoms.

            • fosamprenavir

              ritonavir will increase the level or effect of fosamprenavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • gilteritinib

              ritonavir will increase the level or effect of gilteritinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Consider alternatives to any strong CYP3A4 inhibitor when coadministered with gilteritinib. If such a combination cannot be avoided, closely monitor for gilteritinib-related adverse effects. Interrupt and reduce gilteritinib dosage in patients with serious or life-threatening toxicity.

            • givosiran

              givosiran will increase the level or effect of ritonavir by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sensitive CYP2D6 substrates with givosiran. If unavoidable, decrease the CYP2D6 substrate dosage in accordance with approved product labeling.

            • glasdegib

              ritonavir will increase the level or effect of glasdegib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Consider alternate therapies that are not strong CYP3A inhibitors or monitor for increased risk of adverse effects, including QTc interval prolongation.

            • glecaprevir/pibrentasvir

              ritonavir will increase the level or effect of glecaprevir/pibrentasvir by decreasing metabolism. Avoid or Use Alternate Drug. Avoid coadministration of glecaprevir/pibrentasvir with ritonavir (P-gp and a strong CYP3A4 inhibitor).

            • hydroxychloroquine sulfate

              hydroxychloroquine sulfate and ritonavir both increase QTc interval. Avoid or Use Alternate Drug.

            • ibrutinib

              ritonavir increases levels of ibrutinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid concomitant use of ibrutinib and strong CYP3A4 inhibitors. If a strong CYP3A4 inhibitor must be used short-term (eg, anti-infectives for =7 days), interrupt ibrutinib therapy until strong CYP3A4 inhibitor is discontinued.

            • idelalisib

              ritonavir will increase the level or effect of idelalisib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministered with strong CYP3A inhibitors, monitor for signs of idelalisib toxicity; follow recommendations for dosage modifications if adverse reactions occur

              idelalisib will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Idelalisib is a strong CYP3A inhibitor; avoid coadministration with sensitive CYP3A substrates

            • infigratinib

              ritonavir will increase the level or effect of infigratinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • irinotecan

              ritonavir will increase the level or effect of irinotecan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • irinotecan liposomal

              ritonavir will increase the level or effect of irinotecan liposomal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • isosorbide dinitrate

              ritonavir will increase the level or effect of isosorbide dinitrate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • isosorbide mononitrate

              ritonavir will increase the level or effect of isosorbide mononitrate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • ivosidenib

              ritonavir will increase the level or effect of ivosidenib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of strong CYP3A4 inhibitors with ivosidenib or replace with alternate therapies. If coadministration of a strong CYP3A4 inhibitor is unavoidable, reduce ivosidenib dose to 250 mg qDay. If the strong inhibitor is discontinued, increase ivosidenib dose (after at least 5 half-lives of the strong CYP3A4 inhibitor) to the recommended dose of 500 mg qDay. Monitor for increased risk of QTc interval prolongation.

              ivosidenib will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sensitive CYP3A4 substrates with ivosidenib or replace with alternative therapies. If coadministration is unavoidable, monitor patients for loss of therapeutic effect of these drugs.

            • ketoconazole

              ketoconazole will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • lapatinib

              ritonavir will increase the level or effect of lapatinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • larotrectinib

              ritonavir will increase the level or effect of larotrectinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of larotrectinib with strong CYP3A4 inhibitors is unavoidable, reduce larotrectinib dose by 50%. Resume prior larotrectinib dose once CYP3A4 inhibitor discontinued for 3-5 half-lives.

            • lasmiditan

              lasmiditan increases levels of ritonavir by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug.

            • lefamulin

              ritonavir will increase the level or effect of lefamulin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of lefamulin with strong CYP3A inhibitors.

            • lemborexant

              ritonavir will increase the level or effect of lemborexant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of lemborexant with moderate or strong CYP3A inhibitors.

            • levonorgestrel intrauterine

              ritonavir will increase the level or effect of levonorgestrel intrauterine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • levonorgestrel oral

              ritonavir will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • levonorgestrel oral/ethinylestradiol/ferrous bisglycinate

              ritonavir, levonorgestrel oral/ethinylestradiol/ferrous bisglycinate. Other (see comment). Avoid or Use Alternate Drug. Comment: Significant changes (increase or decrease) can occur in estrogen plasma levels. Efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

            • lorlatinib

              ritonavir will increase the level or effect of lorlatinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministering lorlatinib with strong CYP3A inhibitors. If unavoidable, reduce lorlatinib dose by 25 mg/day. If strong CYP3A inhibitor discontinued, increase to previous lorlatinib (dose after 3 plasma half-lives of strong CYP3A inhibitor). See monograph for further details.

              lorlatinib will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • lurbinectedin

              ritonavir will increase the level or effect of lurbinectedin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • macitentan

              ritonavir will increase the level or effect of macitentan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministering macitentan with strong CYP3A4 inhibitors

            • medroxyprogesterone

              ritonavir will increase the level or effect of medroxyprogesterone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • mefloquine

              ritonavir increases levels of mefloquine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Potential for increased toxicity. Avoid coadministration during and for 15 weeks after discontinuing mefloquine. .

              ritonavir increases toxicity of mefloquine by QTc interval. Avoid or Use Alternate Drug.

            • methylergonovine

              ritonavir increases levels of methylergonovine by decreasing metabolism. Contraindicated.

            • metoclopramide intranasal

              ritonavir will increase the level or effect of metoclopramide intranasal by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Concurrent use of metoclopramide intranasal and strong CYP2D6 inhibitors is not recommended since the metoclopramide intranasal dose cannot be adjusted.

            • midazolam

              ritonavir increases levels of midazolam by decreasing metabolism. Contraindicated.

            • midazolam intranasal

              ritonavir will increase the level or effect of midazolam intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of strong CYP3A4 inhibitors with midazolam intranasal causes higher midazolam systemic exposure, which may prolong sedation.

            • midostaurin

              ritonavir will increase the level or effect of midostaurin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with strong CYP3A4 inhibitors cannot be avoided, monitor midostaurin for increased risk of adverse reactions, especially during the first week of treatment.

            • modafinil

              ritonavir will increase the level or effect of modafinil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • nefazodone

              ritonavir will increase the level or effect of nefazodone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • neratinib

              ritonavir will increase the level or effect of neratinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of neratinib with strong/moderate CYP3A4 inhibitors.

            • nilotinib

              ritonavir will increase the level or effect of nilotinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. May require decreased nilotinib dose or adjustment of dosing interval. Both ritonavir and nilotinib are CYP3A4 inhibitor, however, ritonavir is a strong CYP3A4 inhibitor and more likely to increase nilotinib levels and increase risk for toxicity including prolonged QT interval

            • norgestrel

              ritonavir will increase the level or effect of norgestrel by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • olaparib

              ritonavir will increase the level or effect of olaparib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with strong CYP3A inhibitors cannot be avoided, reduce olaparib dose to 150 mg (capsule) or 100 mg (tablet) PO BID. Do not substitute tablets with capsules.

            • ombitasvir/paritaprevir/ritonavir

              ritonavir will increase the level or effect of ombitasvir/paritaprevir/ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • ombitasvir/paritaprevir/ritonavir & dasabuvir

              ritonavir will increase the level or effect of ombitasvir/paritaprevir/ritonavir & dasabuvir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • osimertinib

              ritonavir will increase the level or effect of osimertinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of osimertinib with strong CYP3A4 inhibitors. If no other alternative treatment exists, monitor patient more closely for adverse effects.

            • oxycodone

              ritonavir increases levels of oxycodone by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Oxycodone dose reduction may be warranted when coadministered with strong CYP3A4 inhibitors.

              ritonavir increases levels of oxycodone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Oxycodone dose reduction may be warranted when coadministered with strong CYP3A4 inhibitors.

            • palbociclib

              ritonavir will increase the level or effect of palbociclib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of palbociclib with strong CYP3A inhibitors. If unable to avoid, reduce palbociclib dose to 75 mg/day.

            • pazopanib

              ritonavir will increase the level or effect of pazopanib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of pazopanib with strong CYP3A4 inhibitors if possible; if must coadminister, decrease pazopanib dose to 400 mg/day

            • pemigatinib

              ritonavir will increase the level or effect of pemigatinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with strong or moderate CYP3A4 inhibitors is unavoidable, reduce pemigatinib dose (refer to drug monograph dosage modifications). After discontinuing the CYP3A4 inhibitor for 3 elimination half-lives, may resume previous pemigatinib dose.

            • pexidartinib

              ritonavir will increase the level or effect of pexidartinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with strong or moderate CYP3A4 inhibitors is unavoidable, reduce pexidartinib dose (refer to drug monograph dosage modifications). After discontinuing the CYP3A4 inhibitor for 3 elimination half-lives, may resume previous pexidartinib dose.

            • pimavanserin

              ritonavir will increase the level or effect of pimavanserin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Decrease dose to 17 mg/day if pimavanserin is coadministered with strong CYP3A4 inhibitors.

            • pomalidomide

              ritonavir increases levels of pomalidomide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

              ritonavir increases levels of pomalidomide by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug.

            • ponatinib

              ritonavir increases levels of ponatinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Decrease ponatinib starting dose to 30 mg qDay if coadministration with strong CYP3A4 inhibitors cannot be avoided.

            • pralsetinib

              ritonavir will increase the level or effect of pralsetinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • propafenone

              ritonavir will increase the level or effect of propafenone by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Concurrent use of propafenone and ritonavir is contraindicated.

              ritonavir increases levels of propafenone by decreasing metabolism. Contraindicated.

            • quazepam

              ritonavir will increase the level or effect of quazepam by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • quinidine

              quinidine will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug.

              ritonavir increases levels of quinidine by decreasing metabolism. Contraindicated.

            • quinine

              ritonavir will increase the level or effect of quinine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Prescribing information for quinine recommends avoiding combination

            • ranolazine

              ritonavir will increase the level or effect of ranolazine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

            • red yeast rice

              ritonavir will increase the level or effect of red yeast rice by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. May increase creatine kinase levels and increase risk of myopathy or rhabdomyolysis; red yeast rice contains monocolin K (reportedly identical to lovastatin)

            • revefenacin

              ritonavir increases levels of revefenacin by Other (see comment). Avoid or Use Alternate Drug. Comment: OATP1B1 and OATP1B3 transport inhibitors may increase systemic exposure of revefenacin's active metabolite. Coadministration not recommended.

            • ribociclib

              ritonavir will increase the level or effect of ribociclib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If a strong CYP3A inhibitor must be coadministered with ribociclib, reduce the ribociclib starting dose to 400 mg/day.

            • rifabutin

              rifabutin will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

              ritonavir will increase the level or effect of rifabutin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • rifampin

              rifampin will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • rifapentine

              rifapentine decreases levels of ritonavir by increasing metabolism. Contraindicated.

            • rimegepant

              ritonavir will increase the level or effect of rimegepant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

              ritonavir will increase the level or effect of rimegepant by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug.

            • riociguat

              ritonavir will increase the level or effect of riociguat by decreasing metabolism. Avoid or Use Alternate Drug. Coadministration of riociguat (substrate of CYP isoenzymes 1A1, 2C8, 3A, 2J2) with strong CYP inhibitors may require a decreased initial dose of 0.5 mg PO TID; monitor for signs of hypotension and reduce dose if needed

              ritonavir will increase the level or effect of riociguat by Other (see comment). Avoid or Use Alternate Drug. Coadministration of riociguat (an ABCG2 [BCRP] substrate) with strong ABCG2 inhibitors may require a decreased initial dose of 0.5 mg PO TID; monitor for signs of hypotension and reduce dose if needed

              ritonavir will increase the level or effect of riociguat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • rivaroxaban

              ritonavir increases levels of rivaroxaban by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid concomitant use of rivaroxaban and combined Pgp and strong CYP3A4 inhibitors. Combination may lead to significant increases in rivaroxaban levels and increase bleeding risk.

            • roflumilast

              ritonavir will increase the level or effect of roflumilast by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • romidepsin

              ritonavir will increase the level or effect of romidepsin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration with strong 3A4 inhibitors should be avoided if possible.

            • rosuvastatin

              ritonavir increases toxicity of rosuvastatin by Other (see comment). Avoid or Use Alternate Drug. Comment: OATP1B1 inhibitors may increase risk of myopathy.

            • ruxolitinib

              ritonavir will increase the level or effect of ruxolitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Reduce ruxolitinib starting dose to 10 mg BID with platelet count 100 X 10^9/L or more and concurrent use of strong CYP3A4 inhibitors; avoid with platelet counts <100 X 10^9/L

            • saquinavir

              saquinavir will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • selpercatinib

              ritonavir will increase the level or effect of selpercatinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • selumetinib

              ritonavir will increase the level or effect of selumetinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with strong or moderate CYP3A4 inhibitors cannot be avoided, reduce selumetinib dosage (refer to selumetinib monograph for further information). After discontinuation of the strong or moderate CYP3A4 inhibitor for 3 elimination half-lives, resume selumetinib dose that was taken before initiating the inhibitor.

            • sildenafil

              ritonavir will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If used concomitantly, monitor for toxicities. Patients receiving indinavir with ritonavir should receive not more than 25 mg of sildenafil for treatment of erectile dysfunction in a 48-hour period, and patients receiving other protease inhibitors should use a lower initial sildenafil dose of 25 mg. Patient taking sildenafil for PAH with ritonavir is not recommended.

            • silodosin

              ritonavir will increase the level or effect of silodosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

            • siponimod

              ritonavir will increase the level or effect of siponimod by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of siponimod with a moderate or strong CYP3A4 inhibitor PLUS a moderate or strong CYP2C9 inhibitor is not recommended.

            • sirolimus

              ritonavir will increase the level or effect of sirolimus by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

            • sonidegib

              ritonavir will increase the level or effect of sonidegib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sonidegib with strong CYP3A4 inhibitors.

            • sotorasib

              sotorasib will decrease the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If use is unavoidable, refer to the prescribing information of the P-gp substrate for dosage modifications.

            • St John's Wort

              St John's Wort decreases levels of ritonavir by increasing metabolism. Contraindicated.

            • stiripentol

              ritonavir will increase the level or effect of stiripentol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • suvorexant

              ritonavir increases levels of suvorexant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Suvorexant not recommended with use of strong CYP3A4 inhibitors.

            • tadalafil

              ritonavir will increase the level or effect of tadalafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Stop tadalafil >24 hours prior to protease inhibitor (PI) initiation, restart 7 days after PI initiation at 20 mg once daily, and increase to 40 mg once daily based on tolerability.

            • tamoxifen

              ritonavir, tamoxifen. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. CYP3A4 inhibition decreases metabolism of tamoxifen to N-desmethyl tamoxifen (active metabolite with similar biologic activity).

            • tamsulosin

              ritonavir increases levels of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • tepotinib

              ritonavir will increase the level or effect of tepotinib by Other (see comment). Avoid or Use Alternate Drug. Interaction not studied clinically. Metabolism and data suggest drugs that are strong CYP3A4 and P-gp inhibitors may increase tepotinib (a P-gp and CYP3A4 substrate) effects and risk of toxicities.

              tepotinib will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If concomitant use unavoidable, reduce the P-gp substrate dosage if recommended in its approved product labeling.

            • thioridazine

              ritonavir will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

            • tofacitinib

              ritonavir increases levels of tofacitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Reduce tofacitinib dose to 5 mg qDay when coadministered with potent CYP3A4 inhibitors.

            • tolvaptan

              ritonavir will increase the level or effect of tolvaptan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

            • topotecan

              ritonavir will increase the level or effect of topotecan by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. Product labeling for PO topotecan recommends avoiding concomitant use of P-gp inhibitors; the interaction with IV topotecan may be less severe but is still likely of clinical significance

            • trabectedin

              ritonavir will increase the level or effect of trabectedin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If strong CYP3A inhibitor must be used, short-term (eg, less than 14 days), administer strong CYP3A inhibitor 1 week after trabectedin infusion, and discontinue the day prior to next trabectedin infusion

            • triazolam

              ritonavir increases levels of triazolam by decreasing metabolism. Contraindicated.

            • tucatinib

              ritonavir will increase the level or effect of tucatinib by Other (see comment). Avoid or Use Alternate Drug. Coadministration of tucatinib (a CYP2C8 substrate) with a strong or moderate CYP2C8 inhibitors increases tucatinib plasma concentrations and risk of toxicities.

              tucatinib will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid concomitant use of tucatinib with CYP3A substrates, where minimal concentration changes may lead to serious or life-threatening toxicities. If unavoidable, reduce CYP3A substrate dose according to product labeling.

            • velpatasvir

              ritonavir will increase the level or effect of velpatasvir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • vemurafenib

              vemurafenib and ritonavir both increase QTc interval. Avoid or Use Alternate Drug. Concomitant use of vemurafenib with drugs that prolong QT interval is not recommended.

              ritonavir increases levels of vemurafenib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • vilazodone

              ritonavir increases levels of vilazodone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Strong CYP3A4 inhibitors may increase vilazodone plasma levels by 50% - Reduce daily dose to 20 mg.

            • vorapaxar

              ritonavir increases levels of vorapaxar by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • voriconazole

              ritonavir will increase the level or effect of voriconazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • vortioxetine

              ritonavir increases levels of vortioxetine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Decrease vortioxetine dose by 50% when coadministered with strong CYP2D6 inhibitors.

            • voxelotor

              ritonavir will increase the level or effect of voxelotor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Voxelotor is primarily metabolized by CYP3A4. Avoid coadministration with strong CYP3A4 inhibitors. If unable to avoid coadministration, reduce voxelotor dose (see Dosage Modifications).

              voxelotor will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Voxelotor increases systemic exposure of sensitive CYP3A4 substrates. Avoid coadministration with sensitive CYP3A4 substrates with a narrow therapeutic index. Consider dose reduction of the sensitive CYP3A4 substrate(s) if unable to avoid.

            • warfarin

              ritonavir, warfarin. Other (see comment). Avoid or Use Alternate Drug. Comment: Variable effect on warfarin levels. Initial frequent monitoring of the INR during co-administration is indicated.

            Monitor Closely (382)

            • abacavir

              ritonavir and abacavir both increase risk of immune reconstitution syndrome. Use Caution/Monitor.

            • abemaciclib

              ritonavir will increase the level or effect of abemaciclib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong CYP3A4 inhibitors increase plasma levels of abemaciclib and its metabolites. Abemaciclib dose reduction required. If a strong CYP3A4 inhibitor is discontinued, increase abemaciclib to the dose prior to initiating the strong inhibitor.

            • abiraterone

              ritonavir increases levels of abiraterone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Avoid or use with caution, strong inhibitors of 3A4 during abiraterone therapy.

            • acarbose

              ritonavir decreases effects of acarbose by pharmacodynamic antagonism. Use Caution/Monitor. New onset or exacerbation of diabetes mellitus and hyperglycemia have been reported with protease inhibitors.

            • albiglutide

              ritonavir decreases effects of albiglutide by Other (see comment). Use Caution/Monitor. Comment: Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

            • alitretinoin

              ritonavir will increase the level or effect of alitretinoin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • almotriptan

              ritonavir will increase the level or effect of almotriptan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • alprazolam

              ritonavir will increase the level or effect of alprazolam by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • amikacin

              ritonavir will increase the level or effect of amikacin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • amitriptyline

              ritonavir will increase the level or effect of amitriptyline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of amitriptyline by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • amlodipine

              ritonavir will increase the level or effect of amlodipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • amobarbital

              amobarbital will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • apalutamide

              ritonavir will increase the level or effect of apalutamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of apalutamide with strong CYP3A4 or CYP2C8 inhibitors does not require initial dosage modification; however, dose reduction may be needed based on tolerability.

            • aprepitant

              aprepitant will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • aripiprazole

              ritonavir will increase the level or effect of aripiprazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • armodafinil

              armodafinil will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • artemether

              ritonavir, artemether. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Ritonavir may increase or decrease levels of artemether.

            • artemether/lumefantrine

              ritonavir, artemether/lumefantrine. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Ritonavir may increase or decrease levels of lumefantrine.

            • artesunate

              ritonavir will decrease the level or effect of artesunate by increasing metabolism. Use Caution/Monitor. Coadministration may decrease AUC and peak plasma concentration of active artesunate metabolite (DHA). Monitor for decreased efficacy.

            • atazanavir

              atazanavir will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              atazanavir and ritonavir both increase risk of immune reconstitution syndrome. Use Caution/Monitor.

            • atomoxetine

              ritonavir will increase the level or effect of atomoxetine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

            • atorvastatin

              ritonavir will increase the level or effect of atorvastatin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              atorvastatin will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • azithromycin

              azithromycin will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • bazedoxifene/conjugated estrogens

              ritonavir will increase the level or effect of bazedoxifene/conjugated estrogens by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of bazedoxifene/conjugated estrogens by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

              ritonavir decreases levels of bazedoxifene/conjugated estrogens by increasing metabolism. Use Caution/Monitor. A reduction in bazedoxifene exposure may be associated with an increase risk of endometrial hyperplasia.

            • benzhydrocodone/acetaminophen

              ritonavir will increase the level or effect of benzhydrocodone/acetaminophen by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Hydromorphone (<3% of the circulating parent hydrocodone [benzhydrocodone is prodrug of hydrocodone]) is mainly formed by CYP2D6 mediated O-demethylation of hydrocodone. Hydromorphone may contribute to the total analgesic effect of hydrocodone.

              ritonavir will increase the level or effect of benzhydrocodone/acetaminophen by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration with strong CYP3A4 inhibitors may increase hydrocodone (benzhydrocodone is prodrug of hydrocodone) plasma concentrations and can result in potentially fatal respiratory depression.

            • benzphetamine

              ritonavir will increase the level or effect of benzphetamine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • berotralstat

              ritonavir increases levels of berotralstat by P-glycoprotein (MDR1) efflux transporter. Modify Therapy/Monitor Closely. Reduced berotralstat dose to 110 mg/day when coadministered with P-gp inhibitors.

              berotralstat will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Monitor or titrate P-gp substrate dose if coadministered.

            • betrixaban

              ritonavir increases levels of betrixaban by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Decrease betrixaban dose to 80 mg PO once, then 40 mg PO qDay if coadministered with a P-gp inhibitor.

            • bexarotene

              ritonavir will increase the level or effect of bexarotene by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • bortezomib

              ritonavir will increase the level or effect of bortezomib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • bosutinib

              bosutinib increases levels of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • brentuximab vedotin

              ritonavir increases levels of brentuximab vedotin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor patients for adverse reactions. .

            • brexpiprazole

              ritonavir will increase the level or effect of brexpiprazole by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Administer half of the usual brexpiprazole dose when coadministered with strong CYP2D6 inhibitors. If also administered with a strong/moderate CYP3A4 inhibitor, administer a quarter of brexpiprazole dose. NOTE: In MDD clinical trials, brexpiprazole dosage was not adjusted for strong CYP2D6 inhibitors (eg, paroxetine, fluoxetine); thus, CYP considerations are already factored into general dosing recommendations and brexpiprazole may be administered without dosage adjustment in patients with MDD.

              ritonavir will increase the level or effect of brexpiprazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Administer half of the usual brexpiprazole dose when coadministered with strong CYP3A4 inhibitors. If also administered with a strong/moderate CYP2D6 inhibitor, administer a quarter of brexpiprazole dose.

            • bromocriptine

              ritonavir increases levels of bromocriptine by decreasing metabolism. Use Caution/Monitor. Increased levels possibly due to CYP3A4 inhibition.

            • budesonide

              ritonavir will increase the level or effect of budesonide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              budesonide will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of budesonide by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • buprenorphine

              ritonavir increases levels of buprenorphine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Potential for increased toxicity.

            • buprenorphine buccal

              ritonavir increases levels of buprenorphine buccal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Potential for increased toxicity.

            • buprenorphine subdermal implant

              ritonavir will increase the level or effect of buprenorphine subdermal implant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Monitor patients already on buprenorphine subdermal implant who require newly-initiated treatment with CYP3A4 inhibitors for signs and symptoms of overmedication. If the dose of the concomitant CYP3A4 inhibitor cannot be reduced or discontinued, implant removal may be necessary and the patient should then be treated with a buprenorphine dosage form that permits dose adjustments. If a CYP3A4 inhibitor is discontinued in a patient who has been stabilized on buprenorphine, monitor the patient for withdrawal.

            • buprenorphine transdermal

              ritonavir will increase the level or effect of buprenorphine transdermal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • buprenorphine, long-acting injection

              ritonavir will increase the level or effect of buprenorphine, long-acting injection by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Patients who transfer to buprenorphine long-acting injection from transmucosal buprenorphine coadministered with CYP3A4 inhibitors should be monitored to ensure buprenorphine plasma levels are adequate. Within 2 weeks, if signs and symptoms of buprenorphine toxicity or overdose occur and the concomitant CYP3A4 inhibitor cannot be reduced or discontinued, transition the patient back to a buprenorphine formulation that permits dose adjustments.

            • bupropion

              ritonavir decreases levels of bupropion by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Ritonavir decreases levels of bupropion by inducing CYP2B6. Bupropion levels decreased by 20-80%, increased doses of bupropion may be required .

            • buspirone

              ritonavir will increase the level or effect of buspirone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • butabarbital

              butabarbital will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • butalbital

              butalbital will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • cabazitaxel

              ritonavir increases levels of cabazitaxel by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Potential for increased toxicity. Avoid coadministration.

            • cabozantinib

              ritonavir will increase the level or effect of cabozantinib by Other (see comment). Use Caution/Monitor. MRP2 inhibitors increase cabozantinib toxicity

            • calcifediol

              ritonavir, calcifediol. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. CYP450 inhibitors may inhibit enzymes involved in vitamin D metabolism (CYP24A1 and CYP27B1). This may alter serum levels of calcifediol and decrease the conversion of calcifediol to calcitriol. Dose adjustment of calcifediol may be required, and serum 25­hydroxyvitamin D, intact PTH, and serum calcium concentrations should be closely monitored when initiating or discontinuing a strong CYP3A4 inhibitor.

            • canagliflozin

              ritonavir decreases levels of canagliflozin by increasing metabolism. Use Caution/Monitor. Coadministration with potent UGT enzyme inducers: Consider increasing dose to 300 mg qDay if 100 mg/day tolerate and additional glycemic control required (eGFR must be >60 mL/min/1.73 m2 to increase dose); if eGFR <60 mL/min/1.73 m2, consider using a different antihyperglycemic agent.

            • cannabidiol

              ritonavir will increase the level or effect of cannabidiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Consider reducing the cannabidiol dose when coadministered with a strong CYP3A4 inhibitor.

            • carbamazepine

              ritonavir will increase the level or effect of carbamazepine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor plasma levels when used concomitantly

            • cariprazine

              ritonavir will increase the level or effect of cariprazine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration with strong CYP3A4 inhibitors requires cariprazine dose reduction. See Dosage Modification section in drug monograph.

            • carvedilol

              ritonavir will increase the level or effect of carvedilol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

            • cenobamate

              cenobamate will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Increase dose of CYP3A4 substrate, as needed, when coadministered with cenobamate.

            • ceritinib

              ritonavir increases levels of ceritinib by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • cetirizine

              ritonavir increases levels of cetirizine by decreasing metabolism. Use Caution/Monitor.

            • chlordiazepoxide

              ritonavir increases levels of chlordiazepoxide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Use alternatives if available. Potential for increased toxicity. Consider lowering benzodiazepine dose.

            • chlorpropamide

              ritonavir, chlorpropamide. Other (see comment). Use Caution/Monitor. Comment: Ritonavir may increase or decrease levels of chlorpropamide. Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

            • cholic acid

              ritonavir increases toxicity of cholic acid by decreasing elimination. Modify Therapy/Monitor Closely. Avoid concomitant use of inhibitors of the bile salt efflux pump (BSEP). May exacerbate accumulation of conjugated bile salts in the liver and result in clinical symptoms. If concomitant use is necessary, monitor serum transaminases and bilirubin.

            • ciclesonide inhaled

              ritonavir increases levels of ciclesonide inhaled by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potential for increased toxicity. Increased risk of Cushing's syndrome or adrenal suppression.

            • cilostazol

              ritonavir will increase the level or effect of cilostazol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • cinacalcet

              ritonavir will increase the level or effect of cinacalcet by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • citalopram

              ritonavir increases levels of citalopram by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Increased risk of serotonin syndrome. ECG monitoring is recommended, along with drugs that may prolong the QT interval.

            • clarithromycin

              clarithromycin will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • clobetasone

              ritonavir will increase the level or effect of clobetasone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of clobetasone by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • clomipramine

              ritonavir will increase the level or effect of clomipramine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of clomipramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • clonazepam

              ritonavir increases levels of clonazepam by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Potential for increased toxicity. Use alternatives if available. Consider lowering benzodiazepine dose.

            • clopidogrel

              ritonavir will decrease the level or effect of clopidogrel by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Inhibition of CYP3A4 will reduce clopidogrel bioactivation

            • clotrimazole

              clotrimazole will decrease the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • clozapine

              ritonavir will increase the level or effect of clozapine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • cocaine

              ritonavir will increase the level or effect of cocaine by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor.

            • codeine

              ritonavir will decrease the level or effect of codeine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Prevents conversion of codeine to its active metabolite morphine.

            • conivaptan

              conivaptan will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • conjugated estrogens

              ritonavir will increase the level or effect of conjugated estrogens by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of conjugated estrogens by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • conjugated estrogens, vaginal

              ritonavir will increase the level or effect of conjugated estrogens, vaginal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of conjugated estrogens, vaginal by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • cortisone

              ritonavir will increase the level or effect of cortisone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              cortisone will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of cortisone by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • crizotinib

              ritonavir increases levels of crizotinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Concomitant use of strong CYP3A inhibitors should be avoided. ECG monitoring is recommended, along with drugs that may prolong the QT interval.

              crizotinib increases levels of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • crofelemer

              crofelemer increases levels of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Crofelemer has the potential to inhibit CYP3A4 at concentrations expected in the gut; unlikely to inhibit systemically because minimally absorbed.

            • cyclophosphamide

              ritonavir will increase the level or effect of cyclophosphamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor.

            • cyclosporine

              ritonavir will increase the level or effect of cyclosporine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of cyclosporine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • dabigatran

              ritonavir will increase the level or effect of dabigatran by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Atrial fibrillation: Avoid coadministering dabigatran with P-gp inhibitors if CrCl <30 mL/min. DVT/PE treatment: Avoid coadministering dabigatran with P-gp inhibitors if CrCl <50 mL/min

            • darifenacin

              darifenacin will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of darifenacin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • darolutamide

              ritonavir will increase the level or effect of darolutamide by Other (see comment). Modify Therapy/Monitor Closely. Darolutamide is a P-gp and CYP3A4 substrate. Closely monitor for increased adverse reactions and modify dose of darolutamide as needed when coadministered with drugs that are both P-gp and strong or moderate CYP3A4 inhibitors.

            • darunavir

              darunavir will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              darunavir and ritonavir both increase risk of immune reconstitution syndrome. Use Caution/Monitor.

            • dasatinib

              dasatinib will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • daunorubicin

              ritonavir will increase the level or effect of daunorubicin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • deferasirox

              ritonavir decreases levels of deferasirox by Other (see comment). Use Caution/Monitor. Comment: Avoid concomitant use of potent UGT inducers with deferasirox. If co-administration is required then consider increasing initial dose of deferasirox to 30 mg/kg and monitor ferritin levels and clinical response.

            • deflazacort

              ritonavir will increase the level or effect of deflazacort by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Decrease deflazacort dose to one-third of the recommended dose if coadministered with moderate or strong CYP3A4 inhibitors.

              ritonavir will increase the level or effect of deflazacort by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • desipramine

              ritonavir will increase the level or effect of desipramine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of desipramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • desvenlafaxine

              ritonavir increases levels of desvenlafaxine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potential for increased toxicity. .

            • deutetrabenazine

              ritonavir will increase the level or effect of deutetrabenazine by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Strong CYP2D6 inhibitors increase the systemic exposure to the active dihydro-metabolites of deutetrabenazine by approximately 3-fold. Do not exceed 18 mg/dose and 36 mg/day of deutetrabenazine if coadministered with strong CYP2D6 inhibitors.

            • dexamethasone

              ritonavir will increase the level or effect of dexamethasone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              dexamethasone will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of dexamethasone by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • dexlansoprazole

              ritonavir will increase the level or effect of dexlansoprazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • DHEA, herbal

              DHEA, herbal will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • diazepam

              ritonavir increases levels of diazepam by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Use alternatives if available.

            • diazepam intranasal

              ritonavir will increase the level or effect of diazepam intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Strong or moderate CYP3A4 inhibitors may decrease rate of diazepam elimination, thereby increasing adverse reactions to diazepam.

            • diazoxide

              ritonavir increases effects of diazoxide by Other (see comment). Use Caution/Monitor. Comment: Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

            • didanosine

              ritonavir and didanosine both increase risk of immune reconstitution syndrome. Use Caution/Monitor.

              ritonavir will decrease the level or effect of didanosine by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor. Didanosine should be taken 1 hour prior or 2 hours after administration of lopinavir/ritonavir oral solution.

            • dienogest/estradiol valerate

              ritonavir will increase the level or effect of dienogest/estradiol valerate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Significant changes (increase or decrease) in plasma levels of estrogen and progestin have been seen when HIV protease inhibitors are administered. Monitor for potential adverse effects such as nausea, irregular uterine bleeding, breast tenderness and headache.

            • digoxin

              ritonavir will increase the level or effect of digoxin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Plasma concentrations and pharmacologic effects of digoxin may be increased by ritonavir. Monitor for increased effects of digoxin.

              ritonavir increases levels of digoxin by decreasing renal clearance. Use Caution/Monitor.

              ritonavir increases levels of digoxin by decreasing hepatic clearance. Use Caution/Monitor.

            • diltiazem

              diltiazem will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of diltiazem by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • docetaxel

              ritonavir will increase the level or effect of docetaxel by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • dofetilide

              ritonavir increases levels of dofetilide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Potential for increased toxicity. Use alternatives if available. Increased risk of QT prolongation and cardiac arrhythmias.

            • doravirine

              ritonavir will increase the level or effect of doravirine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of doravirine and CYP3A4 inhibitors may increase plasma concentrations and toxicities of doravirine.

            • doxepin

              ritonavir will increase the level or effect of doxepin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

            • doxepin cream

              ritonavir will increase the level or effect of doxepin cream by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • doxorubicin

              ritonavir will increase the level or effect of doxorubicin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of doxorubicin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • doxorubicin liposomal

              ritonavir will increase the level or effect of doxorubicin liposomal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of doxorubicin liposomal by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • dronabinol

              ritonavir will increase the level or effect of dronabinol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Dronabinol is a CYP3A4 substrate.

            • dronedarone

              dronedarone will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • duloxetine

              ritonavir will increase the level or effect of duloxetine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

            • duvelisib

              ritonavir will increase the level or effect of duvelisib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration with a strong CYP3A4 inhibitor increases duvelisib AUC, which may increase the risk of duvelisib toxicities. Reduce duvelisib dose to 15 mg BID when coadministered with a strong CYP3A4 inhibitor.

              ritonavir will increase the level or effect of duvelisib by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • efavirenz

              efavirenz will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir and efavirenz both increase risk of immune reconstitution syndrome. Use Caution/Monitor.

            • elagolix

              elagolix will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

              elagolix decreases levels of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Elagolix is a weak-to-moderate CYP3A4 inducer. Monitor CYP3A substrates if coadministered. Consider increasing CYP3A substrate dose if needed.

            • eletriptan

              ritonavir will increase the level or effect of eletriptan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • eliglustat

              eliglustat increases levels of ritonavir by P-glycoprotein (MDR1) efflux transporter. Modify Therapy/Monitor Closely. Monitor therapeutic drug concentrations, as indicated, or consider reducing the dosage of the P-gp substrate and titrate to clinical effect.

              eliglustat increases levels of ritonavir by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Monitor therapeutic drug concentrations, as indicated, or consider reducing the dosage of the concomitant drug and titrate to clinical effect.

            • eluxadoline

              ritonavir increases levels of eluxadoline by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. As a precautionary measure due to incomplete information on the metabolism of eluxadoline, use caution when coadministered with strong CYP2D6 inhibitors.

            • elvitegravir

              ritonavir will increase the level or effect of elvitegravir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • emtricitabine

              ritonavir and emtricitabine both increase risk of immune reconstitution syndrome. Use Caution/Monitor.

            • encorafenib

              encorafenib, ritonavir. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Encorafenib both inhibits and induces CYP3A4 at clinically relevant plasma concentrations. Coadministration of encorafenib with sensitive CYP3A4 substrates may result in increased toxicity or decreased efficacy of these agents.

            • enfortumab vedotin

              ritonavir increases toxicity of enfortumab vedotin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Enfortumab vedotin is an antibody-drug conjugate that releases monomethylauristatin E (MMAE) via proteolytic cleavage. MMAE is primarily metabolized by CYP3A4 in vitro. Coadministration with strong CYP3A4 inhibitors may increase free MMAE exposure, which may increase the incidence or severity of toxicities.

            • enfuvirtide

              ritonavir and enfuvirtide both increase risk of immune reconstitution syndrome. Use Caution/Monitor.

            • erlotinib

              ritonavir will increase the level or effect of erlotinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • erythromycin base

              erythromycin base will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • erythromycin ethylsuccinate

              erythromycin ethylsuccinate will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • erythromycin lactobionate

              erythromycin lactobionate will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • erythromycin stearate

              erythromycin stearate will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • escitalopram

              ritonavir increases levels of escitalopram by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potential for increased toxicity. Increased risk of serotonin syndrome.

            • eslicarbazepine acetate

              eslicarbazepine acetate will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • esomeprazole

              ritonavir will increase the level or effect of esomeprazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • estradiol

              ritonavir will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • estradiol vaginal

              ritonavir will increase the level or effect of estradiol vaginal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration with CYP3A4 inhibitors may increase plasma concentrations of estrogens and toxicities.

            • estrogens conjugated synthetic

              ritonavir will increase the level or effect of estrogens conjugated synthetic by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of estrogens conjugated synthetic by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • estrogens esterified

              ritonavir will increase the level or effect of estrogens esterified by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • estropipate

              ritonavir will increase the level or effect of estropipate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of estropipate by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • eszopiclone

              ritonavir increases levels of eszopiclone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce eszopiclone starting dose to 1 mg/day.

            • ethosuximide

              ritonavir increases levels of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potential for increased toxicity.

            • etonogestrel

              ritonavir will increase the level or effect of etonogestrel by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • etoposide

              ritonavir will increase the level or effect of etoposide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of etoposide by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • etravirine

              ritonavir will increase the level or effect of etravirine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • exenatide injectable solution

              ritonavir decreases effects of exenatide injectable solution by Other (see comment). Use Caution/Monitor. Comment: Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

            • exenatide injectable suspension

              ritonavir decreases effects of exenatide injectable suspension by Other (see comment). Use Caution/Monitor. Comment: Reports of hyperglycemia due to insulin resistance with protease inhibitors.

            • ezogabine

              ezogabine, ritonavir. Either increases toxicity of the other by QTc interval. Use Caution/Monitor. Slight and transient QT-prolongation observed with ezogabine, particularly when dose titrated to 1200 mg/day. QT interval should be monitored when ezogabine is prescribed with agents known to increase QT interval.

            • fedratinib

              fedratinib will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP3A4 substrates as necessary.

              fedratinib will increase the level or effect of ritonavir by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP2D6 substrates as necessary.

            • felodipine

              ritonavir will increase the level or effect of felodipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              felodipine will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • fesoterodine

              ritonavir will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • fluconazole

              fluconazole will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • fludrocortisone

              ritonavir will increase the level or effect of fludrocortisone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              fludrocortisone will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of fludrocortisone by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • flunisolide inhaled

              ritonavir will increase the level or effect of flunisolide inhaled by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • flurazepam

              ritonavir increases levels of flurazepam by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Use alternatives if available. Consider lowering benzodiazepine dose.

            • fluticasone furoate inhaled

              ritonavir will increase the level or effect of fluticasone furoate inhaled by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Strong CYP3A4 inhibitors may increase fluticasone systemic exposure

            • fluticasone inhaled

              ritonavir will increase the level or effect of fluticasone inhaled by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Strong CYP3A4 inhibitors may increase fluticasone systemic exposure

            • fluvastatin

              ritonavir increases toxicity of fluvastatin by Other (see comment). Use Caution/Monitor. Comment: OATP1B1 inhibitors may increase risk of myopathy.

            • fluvoxamine

              fluvoxamine will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • fosamprenavir

              fosamprenavir will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              fosamprenavir and ritonavir both increase risk of immune reconstitution syndrome. Use Caution/Monitor.

            • fosphenytoin

              fosphenytoin will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              fosphenytoin will decrease the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • fostamatinib

              ritonavir will increase the level or effect of fostamatinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong CYP3A4 inhibitors may increase exposure to R406 (fostamatinib major active metabolite). Monitor for toxicities that may require fostamatinib dose reduction.

              fostamatinib will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Concomitant use of fostamatinib may increase concentrations of P-gp substrates. Monitor for toxicities of the P-gp substrate drug that may require dosage reduction when given concurrently with fostamatinib.

            • garlic

              garlic decreases levels of ritonavir by unknown mechanism. Use Caution/Monitor.

            • gefitinib

              ritonavir increases levels of gefitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration of strong CYP3A4 inhibitors may increase risk for gefitinib adverse effects.

            • gentamicin

              ritonavir will increase the level or effect of gentamicin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • glecaprevir/pibrentasvir

              glecaprevir/pibrentasvir will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • glimepiride

              ritonavir, glimepiride. Other (see comment). Use Caution/Monitor. Comment: Ritonavir may increase or decrease levels of glimepiride. Use alternatives if available. Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

            • glipizide

              ritonavir, glipizide. Other (see comment). Use Caution/Monitor. Comment: Ritonavir may increase or decrease levels of glipizide. Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

            • glyburide

              ritonavir, glyburide. Other (see comment). Use Caution/Monitor. Comment: Ritonavir may increase or decrease levels of glyburide. Use alternatives if available. Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

            • grapefruit

              grapefruit will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • griseofulvin

              griseofulvin will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • guanfacine

              ritonavir will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.

            • haloperidol

              ritonavir will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

              haloperidol and ritonavir both increase QTc interval. Use Caution/Monitor.

              ritonavir will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • hydrocodone

              ritonavir will increase the level or effect of hydrocodone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Hydromorphone (<3% of the circulating parent hydrocodone) is mainly formed by CYP2D6 mediated O-demethylation of hydrocodone. Hydromorphone may contribute to the total analgesic effect of hydrocodone.

              ritonavir will increase the level or effect of hydrocodone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration with CYP3A4 inhibitors may increase hydrocodone plasma concentrations and can result in potentially fatal respiratory depression

            • hydrocortisone

              ritonavir will increase the level or effect of hydrocortisone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              hydrocortisone will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of hydrocortisone by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • hydromorphone

              ritonavir will increase the level or effect of hydromorphone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

            • hydroxyprogesterone caproate

              ritonavir will increase the level or effect of hydroxyprogesterone caproate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • ifosfamide

              ritonavir will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.

              ritonavir increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.

            • iloperidone

              ritonavir will increase the level or effect of iloperidone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of iloperidone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              iloperidone increases levels of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Iloperidone is a time-dependent CYP3A inhibitor and may lead to increased plasma levels of drugs predominantly eliminated by CYP3A4.

            • imatinib

              ritonavir will increase the level or effect of imatinib by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • imipramine

              ritonavir will increase the level or effect of imipramine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of imipramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • indacaterol, inhaled

              ritonavir increases levels of indacaterol, inhaled by Other (see comment). Use Caution/Monitor. Comment: Data suggests that systemic clearance is influenced by modulation of both P-gp and CYP3A4 activities. No dose adjustment is warranted at the 75 mcg dose.

              indacaterol, inhaled, ritonavir. QTc interval. Use Caution/Monitor. Drugs that are known to prolong the QTc interval may have an increased the risk of ventricular arrhythmias.

            • indinavir

              indinavir will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of indinavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              indinavir will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

              indinavir and ritonavir both increase risk of immune reconstitution syndrome. Use Caution/Monitor.

            • insulin aspart

              ritonavir decreases effects of insulin aspart by Other (see comment). Use Caution/Monitor. Comment: Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

            • insulin degludec

              ritonavir decreases effects of insulin degludec by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. HIV protease inhibitors may cause new onset diabetes mellitus (DM), exacerbate existing DM, and cause hyperglycemia due to insulin resistance.

            • insulin degludec/insulin aspart

              ritonavir decreases effects of insulin degludec/insulin aspart by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. HIV protease inhibitors may cause new onset diabetes mellitus (DM), exacerbate existing DM, and cause hyperglycemia due to insulin resistance.

            • insulin detemir

              ritonavir decreases effects of insulin detemir by Other (see comment). Use Caution/Monitor. Comment: Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

            • insulin glargine

              ritonavir decreases effects of insulin glargine by Other (see comment). Use Caution/Monitor. Comment: Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

            • insulin glulisine

              ritonavir decreases effects of insulin glulisine by Other (see comment). Use Caution/Monitor. Comment: Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

            • insulin inhaled

              ritonavir decreases effects of insulin inhaled by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. HIV protease inhibitors may cause new onset diabetes mellitus (DM), exacerbate existing DM, and cause hyperglycemia due to insulin resistance.

            • insulin lispro

              ritonavir decreases effects of insulin lispro by Other (see comment). Use Caution/Monitor. Comment: Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

            • insulin NPH

              ritonavir decreases effects of insulin NPH by Other (see comment). Use Caution/Monitor. Comment: Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

            • insulin regular human

              ritonavir decreases effects of insulin regular human by Other (see comment). Use Caution/Monitor. Comment: Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

            • isoniazid

              isoniazid will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • istradefylline

              ritonavir will increase the level or effect of istradefylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Do not exceed istradefylline 20 mg/day if coadministered with strong CYP3A4 inhibitors.

              istradefylline will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Istradefylline 40 mg/day increased peak levels and AUC of CYP3A4 substrates in clinical trials. This effect was not observed with istradefylline 20 mg/day. Consider dose reduction of sensitive CYP3A4 substrates.

              istradefylline will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Istradefylline 40 mg/day increased peak levels and AUC of P-gp substrates in clinical trials. Consider dose reduction of sensitive P-gp substrates.

            • itraconazole

              ritonavir will increase the level or effect of itraconazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Limit itraconazole dose to 200 mg/day in patients receiving ritonavir.

            • ivacaftor

              ritonavir will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

              ivacaftor increases levels of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

            • ivermectin

              ritonavir will increase the level or effect of ivermectin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • ixabepilone

              ritonavir will increase the level or effect of ixabepilone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • ketamine

              ritonavir will decrease the level or effect of ketamine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • ketoconazole

              ketoconazole will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • lacosamide

              ritonavir increases levels of lacosamide by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Potential for increased toxicity. Use alternatives if available. Increased risk of PR prolongation and cardiac arrhythmias.

              ritonavir, lacosamide. Either increases levels of the other by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Consider decreasing lacosamide dose when coadministered with strong CYP3A4 inhibitors.

            • lamivudine

              ritonavir and lamivudine both increase risk of immune reconstitution syndrome. Use Caution/Monitor.

            • lamotrigine

              ritonavir will decrease the level or effect of lamotrigine by increasing metabolism. Use Caution/Monitor. Combination may decrease lamotrigine levels by 50%. Adjust lamotrigine dose as needed when starting, stopping, or changing ritonavir dose. Similar interactions are possible with other RTV-boosted PIs.

            • lapatinib

              lapatinib will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              lapatinib will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • letermovir

              ritonavir increases levels of letermovir by decreasing metabolism. Use Caution/Monitor. Coadminstration of letermovir, an OATP1B1/3 substrate, with OATP1B1/3 inhibitors may increase letermovir plasma concentrations.

              letermovir increases levels of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • levamlodipine

              ritonavir will increase the level or effect of levamlodipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • levocetirizine

              ritonavir increases levels of levocetirizine by decreasing metabolism. Use Caution/Monitor.

            • levomilnacipran

              ritonavir will increase the level or effect of levomilnacipran by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Do not exceed 80 mg/day of levomilnacipran when coadministered with strong CYP3A4 inhibitors

            • linagliptin

              ritonavir increases levels of linagliptin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potential for increased toxicity. .

              ritonavir decreases effects of linagliptin by Other (see comment). Use Caution/Monitor. Comment: Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

            • liraglutide

              ritonavir decreases effects of liraglutide by Other (see comment). Use Caution/Monitor. Comment: Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

            • lofepramine

              ritonavir will increase the level or effect of lofepramine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

            • lofexidine

              ritonavir will increase the level or effect of lofexidine by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Concomitant use of lofexidine with strong CYP2D6 inhibitors may increase lofexidine plasma levels. Monitor for symptoms of orthostasis and bradycardia if coadministered with a CYP2D6 inhibitor. Consider lofexidine dose reduction.

            • lomitapide

              lomitapide increases levels of ritonavir by P-glycoprotein (MDR1) efflux transporter. Modify Therapy/Monitor Closely. Consider reducing dose when used concomitantly with lomitapide.

            • loperamide

              ritonavir will increase the level or effect of loperamide by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • lopinavir

              ritonavir will increase the level or effect of lopinavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • loratadine

              ritonavir will increase the level or effect of loratadine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              loratadine will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • lorcaserin

              lorcaserin will increase the level or effect of ritonavir by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

            • losartan

              ritonavir will increase the level or effect of losartan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • lumacaftor/ivacaftor

              ritonavir increases levels of lumacaftor/ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong CYP3A inhibitors do not impact lumacaftor exposure, but increased ivacaftor exposure by 4.3-fold. Due to the induction effect of lumacaftor on CYP3A, at steady-state the net exposure of ivacaftor is not expected to exceed that when given in the absence of lumacaftor at a dose of 150 mg q12hr (the approved dose of ivacaftor monotherapy). Therefore, no dose adjustment is necessary when CYP3A inhibitors are initiated in patients currently taking lumacaftor/ivacaftor. However, when initiating lumacaftor/ivacaftor in patients taking strong CYP3A inhibitors, reduce the dose to 1 tablet daily (lumacaftor 200 mg/ivacaftor 125 mg total daily dose) for the first week of treatment to allow for the steady-state induction effect of lumacaftor. Following this period, continue with the recommended daily dose. No dose adjustment is required for moderate or weak CYP3A4 inhibitors.

            • lumefantrine

              ritonavir, lumefantrine. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Ritonavir may increase or decrease levels of lumefantrine.

            • maraviroc

              ritonavir will increase the level or effect of maraviroc by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Decrease maraviroc dose to 150 mg BID when coadministered with strong CYP3A4 inhibitors

              ritonavir will increase the level or effect of maraviroc by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • marijuana

              marijuana will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of marijuana by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • meperidine

              ritonavir increases levels of meperidine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potential for increased toxicity.

            • mestranol

              ritonavir will increase the level or effect of mestranol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of mestranol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

              ritonavir decreases levels of mestranol by increasing metabolism. Use Caution/Monitor. May result in contraceptive failure; use additional or alternative method.

            • metformin

              ritonavir decreases effects of metformin by Other (see comment). Use Caution/Monitor. Comment: Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

            • methadone

              ritonavir will increase the level or effect of methadone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir decreases effects of methadone by Other (see comment). Use Caution/Monitor. Comment: Ritonavir may induce the metabolism of methadone and/or induce the p glycoprotein pathway that pumps drugs out of the CNS.

            • methamphetamine

              ritonavir will increase the level or effect of methamphetamine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

            • methylprednisolone

              ritonavir will increase the level or effect of methylprednisolone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              methylprednisolone will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of methylprednisolone by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • metoprolol

              ritonavir will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

            • metronidazole

              metronidazole will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • mexiletine

              ritonavir will increase the level or effect of mexiletine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Monitor patients for signs and symptoms of mexiletine toxicity (nausea, dizziness, cardiac arrhythmias). Therapeutic concentration monitoring is recommended for mexiletine, if available. Reduce doses of mexiletine as required.

            • miconazole vaginal

              miconazole vaginal will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • midazolam

              ritonavir will increase the level or effect of midazolam by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • mifepristone

              ritonavir will increase the level or effect of mifepristone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Do not exceed mifepristone 300 mg/day for Cushing syndrome when coadministered with strong CYP3A4 inhibitors

              mifepristone, ritonavir. QTc interval. Modify Therapy/Monitor Closely. Use alternatives if available.

              mifepristone will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.

            • miglitol

              ritonavir decreases effects of miglitol by Other (see comment). Use Caution/Monitor. Comment: Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

            • mipomersen

              mipomersen, ritonavir. Either increases toxicity of the other by Other (see comment). Use Caution/Monitor. Comment: Both drugs have potential to increase hepatic enzymes; monitor LFTs.

            • mirabegron

              mirabegron will increase the level or effect of ritonavir by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

            • mirtazapine

              ritonavir increases levels of mirtazapine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potential for increased toxicity.

            • mitotane

              mitotane decreases levels of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Mitotane is a strong inducer of cytochrome P-4503A4; monitor when coadministered with CYP3A4 substrates for possible dosage adjustments.

            • modafinil

              modafinil will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • mometasone inhaled

              ritonavir increases levels of mometasone inhaled by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potential for increased toxicity. Increased risk of Cushing's syndrome or adrenal suppression.

            • mometasone, intranasal

              ritonavir will increase the level or effect of mometasone, intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • morphine

              ritonavir will increase the level or effect of morphine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

            • nafcillin

              nafcillin will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • naldemedine

              ritonavir increases levels of naldemedine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor naldemedine for potential adverse effects if coadministered with strong or moderate CYP3A4 inhibitors.

              ritonavir increases levels of naldemedine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Monitor naldemedine for potential adverse effects if coadministered with P-gp inhibitors.

            • nateglinide

              ritonavir decreases effects of nateglinide by Other (see comment). Use Caution/Monitor. Comment: Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

            • nebivolol

              ritonavir will increase the level or effect of nebivolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

            • nefazodone

              nefazodone will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              nefazodone will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • nelfinavir

              nelfinavir will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of nelfinavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of nelfinavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

              nelfinavir and ritonavir both increase risk of immune reconstitution syndrome. Use Caution/Monitor.

            • neomycin PO

              ritonavir will increase the level or effect of neomycin PO by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • netupitant/palonosetron

              ritonavir will increase the level or effect of netupitant/palonosetron by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Netupitant is mainly metabolized by CYP3A4; no dosage adjustment is required

            • nevirapine

              nevirapine will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir and nevirapine both increase risk of immune reconstitution syndrome. Use Caution/Monitor.

              ritonavir will increase the level or effect of nevirapine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • nicardipine

              ritonavir will increase the level or effect of nicardipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              nicardipine will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • nifedipine

              nifedipine will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              nifedipine will decrease the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • nilotinib

              nilotinib will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              nilotinib will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • nintedanib

              ritonavir increases levels of nintedanib by P-glycoprotein (MDR1) efflux transporter. Modify Therapy/Monitor Closely. If nintedanib adverse effects occur, management may require interruption, dose reduction, or discontinuation of therapy .

            • nisoldipine

              ritonavir will increase the level or effect of nisoldipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • norethindrone

              ritonavir will increase the level or effect of norethindrone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • nortriptyline

              ritonavir will increase the level or effect of nortriptyline by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

            • olanzapine

              ritonavir decreases levels of olanzapine by increasing metabolism. Use Caution/Monitor.

            • oliceridine

              ritonavir will increase the level or effect of oliceridine by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. If concomitant use is necessary, may require less frequent oliceridine dosing. Closely monitor for respiratory depression and sedation and titrate subsequent doses accordingly. If inhibitor is discontinued, consider increase oliceridine dosage until stable drug effects are achieved. Monitor for signs of opioid withdrawal.

              ritonavir will increase the level or effect of oliceridine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. If concomitant use is necessary, may require less frequent oliceridine dosing. Closely monitor for respiratory depression and sedation and titrate subsequent doses accordingly. If inhibitor is discontinued, consider increase oliceridine dosage until stable drug effects are achieved. Monitor for signs of opioid withdrawal.

            • olodaterol inhaled

              ritonavir and olodaterol inhaled both increase QTc interval. Use Caution/Monitor. Drugs that prolong the QTc interval and may potentiate the effects of beta2 agonists on the cardiovascular system; increased risk of ventricular arrhythmias

            • omeprazole

              ritonavir will increase the level or effect of omeprazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • ondansetron

              ritonavir and ondansetron both increase QTc interval. Use Caution/Monitor. Avoid with congenital long QT syndrome; ECG monitoring recommended with concomitant medications that prolong QT interval, electrolyte abnormalities, CHF, or bradyarrhythmias. May increase ondansetron levels.

              ritonavir will increase the level or effect of ondansetron by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • orlistat

              orlistat will decrease the level or effect of ritonavir by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Loss of virological control reported in HIV-infected patients taking orlistat concomitantly. Exact mechanism is unclear, but may include a drug-drug interaction that inhibits systemic absorption of the antiretroviral drug. Monitor HIV RNA levels frequently and if increased HIV viral load confirmed, discontinue orlistat.

            • osilodrostat

              ritonavir will increase the level or effect of osilodrostat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce dose of osilodrostat, a CYP3A4 substrate, by half when coadministered with a strong CYP3A4 inhibitor.

            • ospemifene

              ritonavir increases levels of ospemifene by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • oxcarbazepine

              oxcarbazepine will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • oxymorphone

              ritonavir will increase the level or effect of oxymorphone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

            • ozanimod

              ritonavir will increase the level or effect of ozanimod by Other (see comment). Modify Therapy/Monitor Closely. Coadministration of ozanimod (a CYP2C8 substrate) with strong CYP2C8 inhibitors increases the exposure of the active metabolites (CC112273 and CC1084037) of ozanimod, which may increase the risk of ozanimod adverse reactions. Therefore, coadministration of ozanimod with strong CYP2C8 inhibitors is not recommended.

              ozanimod and ritonavir both increase QTc interval. Modify Therapy/Monitor Closely. The potential additive effects on heart rate, treatment with ozanimod should generally not be initiated in patients who are concurrently treated with QT prolonging drugs with known arrhythmogenic properties.

            • paclitaxel

              ritonavir will increase the level or effect of paclitaxel by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

              ritonavir will increase the level or effect of paclitaxel by Other (see comment). Modify Therapy/Monitor Closely. Paclitaxel levels/toxicity may increase when coadministered with CYP2C8 inhibitors

            • paclitaxel protein bound

              ritonavir will increase the level or effect of paclitaxel protein bound by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

              ritonavir will increase the level or effect of paclitaxel protein bound by Other (see comment). Modify Therapy/Monitor Closely. Paclitaxel levels/toxicity may increase when coadministered with CYP2C8 inhibitors

            • paliperidone

              ritonavir will increase the level or effect of paliperidone by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • panobinostat

              ritonavir increases levels of panobinostat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce panobinostat starting dose to 10 mg if coadministered with strong CYP3A4 inhibitors.

            • paricalcitol

              ritonavir increases levels of paricalcitol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potential for increased toxicity.

            • paromomycin

              ritonavir will increase the level or effect of paromomycin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • paroxetine

              ritonavir will increase the level or effect of paroxetine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

            • peginterferon alfa 2b

              peginterferon alfa 2b, ritonavir. Other (see comment). Use Caution/Monitor. Comment: When patients are administered peginterferon alpha-2b with CYP2D6 substrates, the therapeutic effect of these drugs may be altered. Peginterferon alpha-2b may increase or decrease levels of CYP2D6 substrate. The concomitant use of interferons and anti-retroviral protease inhibitors should be done with caution as both can cause hepatic damage. .

            • pentobarbital

              pentobarbital will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • perampanel

              ritonavir will increase the level or effect of perampanel by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • phenobarbital

              phenobarbital will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              phenobarbital will decrease the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • phenytoin

              phenytoin will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              phenytoin will decrease the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • pitavastatin

              ritonavir increases toxicity of pitavastatin by Other (see comment). Use Caution/Monitor. Comment: OATP1B1 inhibitors may increase risk of myopathy.

            • pitolisant

              ritonavir will increase the level or effect of pitolisant by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. If coadministered with strong CYP2D6 inhibitors, initiate pitolisant at 8.9 mg/day and increase after 7 days to maximum of 17.8 mg/day. For patients currently taking pitolisant, reduce pitolisant dose by half upon initiating strong CYP2D6 inhibitors.

            • polatuzumab vedotin

              ritonavir will increase the level or effect of polatuzumab vedotin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Polatuzumab undergoes catabolism to small peptides, amino acids, monomethyl auristatin E (MMAE), and unconjugated MMAE-related catabolites. MMAE is a CYP3A4 substrate. Coadministration of polatuzumab vedotin with a strong CYP3A4 inhibitor may increase unconjugated MMAE AUC, which may increase polatuzumab vedotin toxicities.

            • ponatinib

              ponatinib increases levels of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • posaconazole

              posaconazole will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of posaconazole by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • pramlintide

              ritonavir decreases effects of pramlintide by Other (see comment). Use Caution/Monitor. Comment: Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

            • pravastatin

              ritonavir increases toxicity of pravastatin by Other (see comment). Use Caution/Monitor. Comment: OATP1B1 inhibitors may increase risk of myopathy.

            • praziquantel

              ritonavir will increase the level or effect of praziquantel by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • prednisolone

              ritonavir will increase the level or effect of prednisolone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of prednisolone by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • prednisone

              ritonavir will increase the level or effect of prednisone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              prednisone will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of prednisone by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • primidone

              primidone will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • progesterone intravaginal gel

              ritonavir will increase the level or effect of progesterone intravaginal gel by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • progesterone micronized

              ritonavir will increase the level or effect of progesterone micronized by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • progesterone, natural

              ritonavir will increase the level or effect of progesterone, natural by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • propranolol

              ritonavir will increase the level or effect of propranolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

            • quercetin

              quercetin will decrease the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • quetiapine

              ritonavir will increase the level or effect of quetiapine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              quetiapine, ritonavir. Either increases toxicity of the other by QTc interval. Use Caution/Monitor. Avoid use with drugs that prolong QT and in patients with risk factors for prolonged QT interval. Postmarketing cases show QT prolongation with overdose in patients with concomitant illness or with drugs known to cause electrolyte imbalance or prolong QT.

            • quinidine

              ritonavir will increase the level or effect of quinidine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • quinupristin/dalfopristin

              quinupristin/dalfopristin will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • ranolazine

              ranolazine will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • repaglinide

              ritonavir will increase the level or effect of repaglinide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • ribociclib

              ribociclib will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.

            • rifabutin

              ritonavir increases levels of rifabutin by decreasing metabolism. Use Caution/Monitor.

            • rifampin

              rifampin will decrease the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • rifapentine

              rifapentine will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • rifaximin

              ritonavir increases levels of rifaximin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • rilpivirine

              ritonavir increases levels of rilpivirine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. No dose adjustment is required during concurrent use.

              rilpivirine increases toxicity of ritonavir by QTc interval. Use Caution/Monitor. Rilpivirine should be used with caution when co-administered with a drug with a known risk of Torsade de Pointes.

            • ripretinib

              ritonavir will increase the level or effect of ripretinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration with a strong CYP3A inhibitor will increase systemic exposure to ripretinib and its active metabolite (DP-5439), which may increase risk of adverse reactions.

            • risperidone

              ritonavir will increase the level or effect of risperidone by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • roflumilast

              ritonavir will decrease the level or effect of roflumilast by affecting hepatic enzyme CYP1A2 metabolism. Modify Therapy/Monitor Closely. Concomitant therapy may reduce therapeutic effectiveness.

            • rolapitant

              rolapitant will increase the level or effect of ritonavir by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Rolapitant may increase plasma concentrations of CYP2D6 substrates for at least 28 days following rolapitant administration.

            • romidepsin

              ritonavir will increase the level or effect of romidepsin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • rosiglitazone

              ritonavir decreases effects of rosiglitazone by Other (see comment). Use Caution/Monitor. Comment: Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

            • rosuvastatin

              ritonavir will increase the level or effect of rosuvastatin by decreasing metabolism. Use Caution/Monitor.

            • rucaparib

              rucaparib will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust dosage of CYP3A4 substrates, if clinically indicated.

            • rufinamide

              rufinamide will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • sacubitril/valsartan

              ritonavir will increase the level or effect of sacubitril/valsartan by Other (see comment). Use Caution/Monitor. The results from an in vitro study with human liver tissue indicate that valsartan is a substrate of the hepatic uptake transporter OATP1B1; coadministration with OATP1B1 inhibitors may increase valsartan systemic exposure

              ritonavir will increase the level or effect of sacubitril/valsartan by Mechanism: decreasing hepatic clearance. Use Caution/Monitor. The results from an in vitro study with human liver tissue indicate that valsartan is a substrate of the hepatic efflux transporter MRP2; coadministration of inhibitors of the efflux transporter may increase the systemic exposure to valsartan

            • saquinavir

              ritonavir will increase the level or effect of saquinavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Saquinavir is intended to be administered with ritonavir (boosted therapy). The combination has shown to cause dose-dependent QT and PR interval prolongation. Caution in treatment naïve patients. Reduce starting dose and perform an on-treatment ECG after approximately 10 days.

              ritonavir will increase the level or effect of saquinavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

              ritonavir and saquinavir both increase risk of immune reconstitution syndrome. Use Caution/Monitor.

            • sarecycline

              sarecycline will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Monitor for toxicities of P-gp substrates that may require dosage reduction when coadministered with P-gp inhibitors.

            • saxagliptin

              ritonavir will increase the level or effect of saxagliptin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Limit saxagliptin dose to 2.5 mg/day when coadministered with strong CYP3A4 inhibitors

            • secobarbital

              secobarbital will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • sertraline

              ritonavir increases levels of sertraline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Increased risk of serotonin syndrome.

            • silodosin

              ritonavir will increase the level or effect of silodosin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • sirolimus

              ritonavir will increase the level or effect of sirolimus by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • sitagliptin

              ritonavir decreases effects of sitagliptin by Other (see comment). Use Caution/Monitor. Comment: Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

            • solifenacin

              ritonavir will increase the level or effect of solifenacin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • sorafenib

              ritonavir will increase the level or effect of sorafenib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • St John's Wort

              St John's Wort will decrease the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • stavudine

              ritonavir and stavudine both increase risk of immune reconstitution syndrome. Use Caution/Monitor.

            • stiripentol

              stiripentol, ritonavir. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Stiripentol is a CYP3A4 inhibitor and inducer. Monitor CYP3A4 substrates coadministered with stiripentol for increased or decreased effects. CYP3A4 substrates may require dosage adjustment.

              stiripentol will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Modify Therapy/Monitor Closely. Consider reducing the dose of P-glycoprotein (P-gp) substrates, if adverse reactions are experienced when administered concomitantly with stiripentol.

            • streptomycin

              ritonavir will increase the level or effect of streptomycin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • sufentanil SL

              ritonavir will increase the level or effect of sufentanil SL by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of sufentanil SL with any CYP3A4 inhibitor may increase sufentanil plasma concentration, and, thereby increase or prolonged adverse effects, including potentially fatal respiratory depression.

            • sunitinib

              ritonavir will increase the level or effect of sunitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • tacrolimus

              ritonavir will increase the level or effect of tacrolimus by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              ritonavir will increase the level or effect of tacrolimus by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • tacrolimus ointment

              ritonavir will increase the level or effect of tacrolimus ointment by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • talazoparib

              ritonavir will increase the level or effect of talazoparib by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Talazoparib is a P-glycoprotein (P-gp) substrate; coadministration with P-gp inhibitors may increase talazoparib systemic exposure.

            • tamoxifen

              ritonavir, tamoxifen. affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. CYP2D6 inhibition decreases metabolism of tamoxifen to hydroxytamoxifen, and N-desmethyl tamoxifen to endoxifen (active metabolites with 100-fold greater affinity for estrogen receptor); decreased endoxifen levels may result in poor clinical outcome.

            • tamsulosin

              ritonavir increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

            • tasimelteon

              ritonavir will increase the level or effect of tasimelteon by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • tazemetostat

              ritonavir will decrease the level or effect of tazemetostat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              tazemetostat will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • tecovirimat

              tecovirimat will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Tecovirimat is a weak CYP3A4 inducer. Monitor sensitive CYP3A4 substrates for effectiveness if coadministered.

            • temsirolimus

              ritonavir will increase the level or effect of temsirolimus by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • teniposide

              ritonavir will increase the level or effect of teniposide by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

              ritonavir will increase the level or effect of teniposide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • tenofovir DF

              ritonavir and tenofovir DF both increase risk of immune reconstitution syndrome. Use Caution/Monitor.

              ritonavir increases levels of tenofovir DF by decreasing elimination. Use Caution/Monitor.

            • terbinafine

              terbinafine will increase the level or effect of ritonavir by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Assess need to reduce dose of CYP2D6-metabolized drug.

              ritonavir will increase the level or effect of terbinafine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • tetrabenazine

              ritonavir increases effects of tetrabenazine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Decrease tetrabenazine dose by 50% when coadministered with strong CYP2D6 inhibitors.

            • tezacaftor

              ritonavir will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.

            • theophylline

              ritonavir will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • tiagabine

              ritonavir will increase the level or effect of tiagabine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • ticagrelor

              ritonavir increases levels of ticagrelor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Ticagrelor is metabolized by CYP3A4/5. Avoid use with strong CYP3A inhibitors.

            • timolol

              ritonavir increases levels of timolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Potential for increased toxicity. Increased risk of hypotension, bradycardia, AV block, and prolonged PR interval. Consider lowering beta blocker dose.

            • tinidazole

              ritonavir will increase the level or effect of tinidazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • tipranavir

              ritonavir will increase the level or effect of tipranavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of tipranavir with ritonavir is essential to achieve effective tipranavir plasma concentrations (boosted therapy).

              ritonavir and tipranavir both increase risk of immune reconstitution syndrome. Use Caution/Monitor.

            • tobramycin

              ritonavir will increase the level or effect of tobramycin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • tolazamide

              ritonavir, tolazamide. Other (see comment). Use Caution/Monitor. Comment: Ritonavir may increase or decrease levels of tolazamide. Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

            • tolbutamide

              ritonavir, tolbutamide. Other (see comment). Use Caution/Monitor. Comment: Ritonavir may increase or decrease levels of tolbutamide. Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

            • tolterodine

              ritonavir will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • tolvaptan

              ritonavir will increase the level or effect of tolvaptan by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

              tolvaptan will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • topiramate

              topiramate will decrease the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • toremifene

              ritonavir increases levels of toremifene by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Metabolism of toremifene may be inhibited by drugs known to inhibit CYP3A4 hepatic enzymes.

            • tramadol

              ritonavir will increase the level or effect of tramadol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. May require decreased tramadol dose or adjustment of dosing interval; increased risk for serious adverse events including seizures and serotonin syndrome

            • trazodone

              ritonavir will increase the level or effect of trazodone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.

              trazodone will decrease the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • triamcinolone acetonide injectable suspension

              ritonavir will increase the level or effect of triamcinolone acetonide injectable suspension by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • triazolam

              ritonavir will increase the level or effect of triazolam by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • trimipramine

              ritonavir will increase the level or effect of trimipramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • tucatinib

              tucatinib will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Consider reducing the dosage of P-gp substrates, where minimal concentration changes may lead to serious or life-threatening toxicities.

            • ubrogepant

              ritonavir will decrease the level or effect of ubrogepant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Dose adjustment is recommended with concomitant use of ubrogepant and moderate and weak CYP3A4 inducers. (see Dosage Modifications)

            • ulipristal

              ritonavir will increase the level or effect of ulipristal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • umeclidinium bromide/vilanterol inhaled

              ritonavir will increase the level or effect of umeclidinium bromide/vilanterol inhaled by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Vilanterol is a CYP3A4 substrate; coadministration with potent CYP3A4 inhibitors may increase systemic exposure

            • upadacitinib

              ritonavir will increase the level or effect of upadacitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Caution if upadacitinib is coadministered with strong CYP3A4 inhibitors.

            • valbenazine

              ritonavir will increase the level or effect of valbenazine by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Consider reducing valbenazine dose based on tolerability if coadministered with a strong CYP2D6 inhibitor.

              ritonavir will increase the level or effect of valbenazine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce valbenazine dose to 40 mg once daily when coadministered with a strong CYP3A4 inhibitor.

            • valsartan

              ritonavir will increase the level or effect of valsartan by Other (see comment). Use Caution/Monitor. The results from an in vitro study with human liver tissue indicate that valsartan is a substrate of the hepatic uptake transporter OATP1B1; coadministration with OATP1B1 inhibitors may increase valsartan systemic exposure

              ritonavir will increase the level or effect of valsartan by Mechanism: decreasing hepatic clearance. Use Caution/Monitor. The results from an in vitro study with human liver tissue indicate that valsartan is a substrate of the hepatic efflux transporter MRP2; coadministration of inhibitors of the efflux transporter may increase the systemic exposure to valsartan

            • vardenafil

              ritonavir will increase the level or effect of vardenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • vemurafenib

              ritonavir increases levels of vemurafenib by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

              vemurafenib increases levels of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • venlafaxine

              ritonavir increases levels of venlafaxine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potential for increased toxicity. .

            • verapamil

              ritonavir will increase the level or effect of verapamil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              verapamil will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • vilanterol/fluticasone furoate inhaled

              ritonavir will increase the level or effect of vilanterol/fluticasone furoate inhaled by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Fluticasone furoate and vilanterol are both CYP3A4 substrates; coadministration with potent CYP3A4 inhibitors may increase systemic exposure

            • vinblastine

              ritonavir will increase the level or effect of vinblastine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • vincristine

              ritonavir will increase the level or effect of vincristine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • vincristine liposomal

              ritonavir will increase the level or effect of vincristine liposomal by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

            • warfarin

              ritonavir will increase the level or effect of warfarin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • zafirlukast

              zafirlukast will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • zanubrutinib

              ritonavir will increase the level or effect of zanubrutinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce zanubrutinib dose when coadministered with a strong CYP3A4 inhibitor. Interrupt dose as recommended for adverse reactions. After discontinuing the CYP3A4 inhibitor, resume previous dose of zanubrutinib. See zanubrutinib Dosage Modifications for precise recommendation.

            • zidovudine

              ritonavir and zidovudine both increase risk of immune reconstitution syndrome. Use Caution/Monitor.

            • zileuton

              ritonavir increases levels of zileuton by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potential for increased toxicity. .

            Minor (70)

            • alfentanil

              ritonavir will increase the level or effect of alfentanil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • aliskiren

              ritonavir will increase the level or effect of aliskiren by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

              ritonavir will increase the level or effect of aliskiren by P-glycoprotein (MDR1) efflux transporter. Minor/Significance Unknown.

            • alosetron

              ritonavir will increase the level or effect of alosetron by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • alvimopan

              ritonavir will increase the level or effect of alvimopan by P-glycoprotein (MDR1) efflux transporter. Minor/Significance Unknown.

            • aripiprazole

              ritonavir will increase the level or effect of aripiprazole by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

            • armodafinil

              ritonavir will increase the level or effect of armodafinil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

              ritonavir will increase the level or effect of armodafinil by P-glycoprotein (MDR1) efflux transporter. Minor/Significance Unknown.

            • atazanavir

              ritonavir will increase the level or effect of atazanavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • bosentan

              ritonavir will increase the level or effect of bosentan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • cevimeline

              ritonavir will increase the level or effect of cevimeline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • chlorpromazine

              ritonavir will increase the level or effect of chlorpromazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

            • clarithromycin

              ritonavir will increase the level or effect of clarithromycin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • dapsone

              ritonavir will increase the level or effect of dapsone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • dexfenfluramine

              ritonavir will increase the level or effect of dexfenfluramine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

            • dextroamphetamine

              ritonavir will increase the level or effect of dextroamphetamine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

            • dextromethorphan

              ritonavir will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

            • disopyramide

              ritonavir will increase the level or effect of disopyramide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • docetaxel

              ritonavir will increase the level or effect of docetaxel by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • donepezil

              ritonavir will increase the level or effect of donepezil by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

              ritonavir will increase the level or effect of donepezil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • dutasteride

              ritonavir will increase the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • efavirenz

              ritonavir will increase the level or effect of efavirenz by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • encainide

              ritonavir will increase the level or effect of encainide by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

            • eplerenone

              ritonavir will increase the level or effect of eplerenone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • eucalyptus

              ritonavir will increase the level or effect of eucalyptus by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • fesoterodine

              ritonavir will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

            • fexofenadine

              ritonavir will increase the level or effect of fexofenadine by P-glycoprotein (MDR1) efflux transporter. Minor/Significance Unknown.

            • finasteride

              ritonavir will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • fluoxetine

              ritonavir will increase the level or effect of fluoxetine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

            • fluphenazine

              ritonavir will increase the level or effect of fluphenazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

            • food

              food increases levels of ritonavir by enhancing GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.

            • galantamine

              ritonavir will increase the level or effect of galantamine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

              ritonavir will increase the level or effect of galantamine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • imatinib

              ritonavir will increase the level or effect of imatinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • isradipine

              ritonavir will increase the level or effect of isradipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • ixazomib

              ritonavir, ixazomib. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown. In clinical trials, coadministration of ixazomib with strong CYP3A inhibitors did not result in a clinically meaningful change in the systemic exposure of ixazomib.

            • ketoconazole

              ritonavir will increase the level or effect of ketoconazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • lansoprazole

              ritonavir will increase the level or effect of lansoprazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • loratadine

              ritonavir will increase the level or effect of loratadine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

              ritonavir will increase the level or effect of loratadine by P-glycoprotein (MDR1) efflux transporter. Minor/Significance Unknown.

            • mefloquine

              mefloquine decreases levels of ritonavir by unknown mechanism. Minor/Significance Unknown.

            • meperidine

              ritonavir decreases levels of meperidine by increasing metabolism. Minor/Significance Unknown. Ritonavir induces the metabolism of meperidine to normeperidine, increasing CNS toxicity.

            • montelukast

              ritonavir will increase the level or effect of montelukast by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • nifedipine

              ritonavir will increase the level or effect of nifedipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • nimodipine

              ritonavir will increase the level or effect of nimodipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • nitrendipine

              ritonavir will increase the level or effect of nitrendipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • oxybutynin

              ritonavir will increase the level or effect of oxybutynin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • paclitaxel

              ritonavir will increase the level or effect of paclitaxel by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • paclitaxel protein bound

              ritonavir will increase the level or effect of paclitaxel protein bound by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • parecoxib

              ritonavir will increase the level or effect of parecoxib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • perhexiline

              ritonavir will increase the level or effect of perhexiline by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

            • perphenazine

              ritonavir will increase the level or effect of perphenazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

            • pimozide

              ritonavir will increase the level or effect of pimozide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • pioglitazone

              ritonavir will increase the level or effect of pioglitazone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • prochlorperazine

              ritonavir will increase the level or effect of prochlorperazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

            • promazine

              ritonavir will increase the level or effect of promazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

            • promethazine

              ritonavir will increase the level or effect of promethazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

            • propafenone

              ritonavir will increase the level or effect of propafenone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • rabeprazole

              ritonavir will increase the level or effect of rabeprazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • ramelteon

              ritonavir will increase the level or effect of ramelteon by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • risperidone

              ritonavir will increase the level or effect of risperidone by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

            • selexipag

              ritonavir will increase the level or effect of selexipag by decreasing metabolism. Minor/Significance Unknown. Coadministration of selexipag with ritonavir may result in an increase in exposure to selexipag. Despite this pharmacokinetic change, this interaction is likely of little clinical significance

            • sufentanil

              ritonavir will increase the level or effect of sufentanil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • tolterodine

              ritonavir will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

            • trifluoperazine

              ritonavir will increase the level or effect of trifluoperazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

            • tropisetron

              ritonavir will increase the level or effect of tropisetron by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

            • vinblastine

              ritonavir will increase the level or effect of vinblastine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • vincristine

              ritonavir will increase the level or effect of vincristine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • vincristine liposomal

              ritonavir will increase the level or effect of vincristine liposomal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • vinorelbine

              ritonavir will increase the level or effect of vinorelbine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • zaleplon

              ritonavir will increase the level or effect of zaleplon by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • ziprasidone

              ritonavir will increase the level or effect of ziprasidone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • zolpidem

              ritonavir will increase the level or effect of zolpidem by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • zonisamide

              ritonavir will increase the level or effect of zonisamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

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            Adverse Effects

            >10%

            Increased triglycerides (17-34%)

            Diarrhea (15-23%)

            Nausea (26-30%)

            Taste perversion (7-11%)

            Vomiting (14-17%)

            Weakness (10-15%)

            Increased GGT (5-20%)

            Increased creatinine phosphokinase (9-12%)

            1-10%

            Abdominal pain (6%)

            Anorexia (2-8%)

            Dizziness (3-4%)

            Dyspepsia (6%)

            Eosinophilia

            Fever (1-2%)

            Flatulence (1-2%)

            Headache (6-7%)

            Insomnia (2-3%)

            Increased uric acid (4%)

            Increased LFTs (6-10%)

            Local throat irritation (2-3%)

            Malaise (1-2%)

            Myalgia (2%)

            Diaphoresis (2-3%)

            Paresthesia (3-7)

            Pharyngitis (1-3%)

            Rash (<4%)

            Somnolence (2-3%)

            Pharyngitis (1-3%)

            <1%

            Adrenal suppression

            Cerebral ischemia

            Dementia

            Edema

            Leukopenia

            Tachycardia

            Ulcerative colitis

            Postmarketing Reports

            Renal and urinary disorders: Nephrolithiasis

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            Warnings

            Black Box Warnings

            Coadministration with sedative-hypnotics, antiarrhythmics, or ergot alkaloids may result in serious and/or life-threatening adverse events due to ritonavir’s effect on hepatic metabolism

            Ritonavir inhibits CYP450 3A; drugs that are extensively metabolized by CYP3A and have high first pass metabolism are most susceptible to increased serum levels when coadministered

            Contraindications

            Known hypersensitivity to ritonavir (eg, toxic epidermal necrolysis, Stevens- Johnson syndrome)

            Coadministration with drugs highly dependent on CYP3A for clearance or that significantly reduce ritonavir

            Coadministration of ritonavir with the following drugs is contraindicated: alfuzosin, amiodarone, flecainide, propafenone, quinidine, voriconazole, rifampin, dihydroergotamine, ergotamine, methylergonovine, cisapride, lomitapide, lovastatin, simvastatin, lurasidone, apalutamide, pimozide, sildenafil for pulmonary arterial hypertension, triazolam, oral midazolam, carbamazepine, ranolazine, dronedarone, flecainide, colchicine, phenobarbital, phenytoin, and St. John’s wort

            Cautions

            Do not administer with antacids; separate from didanosine by 2 hr

            Potent inhibitor of CYP3A4 (but also induces CYP450 enzymes)

            Monitor: monthly neurologic evaluation

            Risk of immune reconstitution syndrome if used in combination with other antiretroviral drugs

            Risks of hemolytic anemia and hyperbilirubinemia if used in combination with other antiretroviral drugs

            Capsules must be kept refrigerated

            Allergic reactions have been reported and include anaphylaxis, toxic epidermal necrolysis, Stevens-Johnson Syndrome, bronchospasm and angioedema; discontinue treatment if severe reactions develop

            Consider drug-drug interaction potential to reduce risk of serious or life-threatening adverse reactions

            Oral solution not for administration in preterm neonates in the immediate postnatal period; may cause toxicity; safety and efficacy not established

            Monitor liver function before and during therapy, especially in patients with underlying hepatic disease, including hepatitis B and hepatitis C, or marked transaminase elevations; fatalities resulting from hepatic reactions reported

            Fatalities resulting from pancreatitis reported; suspend therapy as clinically appropriate

            PR interval prolongation reported in some patients; cases of second and third degree heart block reported; use with caution with patients with preexisting conduction system disease, ischemic heart disease, cardiomyopathy, underlying structural heart disease or when administering with other drugs that may prolong the PR interval

            Total cholesterol and triglycerides elevations may occur; monitor prior to therapy and periodically thereafter

            Patients may develop new onset or exacerbations of diabetes mellitus, hyperglycemia

            Patients may develop redistribution/accumulation of body fat

            Spontaneous bleeding may occur; additional factor VIII may be required

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            Pregnancy & Lactation

            Pregnancy

            Advise pregnant women not to use oral solution during pregnancy owing to its alcohol content

            Inform patients that there is an antiretroviral (ARVs) pregnancy registry that monitors fetal outcomes of pregnant women exposed to ARVs 1–800–258–4263

            Follow current CDC/WHO recommendations for HIV treatment during pregnancy

            Lactation

            Excreted in human milk

            The CDC recommends that HIV-1-infected mothers in the United States not breastfeed their infants to avoid risking postnatal transmission of HIV-1 infection, risk of developing viral resistance (in HIV-positive infants), and risk of serious adverse reactions

            Pregnancy Categories

            A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

            B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

            C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

            D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

            X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

            NA: Information not available.

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            Pharmacology

            Mechanism of Action

            Protease Inhibitor; inhibits cleavage of Gag-Pol polyprotein precursors, which in turn causes the formation of immature, noninfectious viral particles.

            Combination use recommended; typically used to boost levels of other protease inhibitors

            Pharmacokinetics

            Absorption: variable, with or without food

            Vd: 0.16-0.66 L/kg (high concentrations in serum & lymph nodes)

            Protein Bound: 98-99%

            Metabolism: Hepatic; five metabolites, low concentration of an active metabolite achieved in plasma (oxidative)

            Half-life: 3-5 hr

            Peak plasma time: 2 hr (oral solution)

            Excretion: Urine (11%); feces (86%)

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            Administration

            Oral Administration

            Gradually increase dose to avoid nausea/vomiting

            Take with food

            Swallow capsules or tablets whole; do not chew or crush

            Oral solution

            • May mix with chocolate milk, Ensure, or Advera within 1 hr of dosing to improve taste
            • Measure dose precisely with calibrated oral syringe

            Oral powder

            • Should be mixed with soft food (eg, apple sauce, vanilla pudding) or mixed with liquid (eg, water, chocolate milk, infant formula) within 2 hr of preparation
            • If not administered within 2 hr of preparation, the mixture should be discarded and a new dose prepared
            • Bitter aftertaste may be lessened if administered with food
            • May administer via feeding tube if mixed with water

            Storage

            Tablets

            • Store at or below 30°C (86°F)
            • Exposure to temperatures up to 50°C (122°F) for 7 days permitted
            • Dispense in original container or USP equivalent tight container (≤60 mL)
            • Inform patients that exposure of the tablets to high humidity outside the original container for >2 weeks is not recommended

            Capsules

            • Store soft gelatin capsules refrigerated at 2-8°C (36-46°F) until dispensed
            • Refrigeration by the patient is recommended, but not required if used within 30 days and stored at <25°C (77°F)
            • Protect from light
            • Avoid exposure to excessive heat
            • Store and dispensed in the original container
            • Keep cap tightly closed

            Oral solution

            • Store at room temperature 20-25°C (68-77°F)
            • Do not refrigerate
            • Shake well before each use
            • Use by product expiration date
            • Store and dispensed in the original container
            • Avoid exposure to excessive heat
            • Keep cap tightly closed

            Oral powder

            • Store at or below 30°C (86°F)
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            Images

            BRAND FORM. UNIT PRICE PILL IMAGE
            Norvir oral
            -
            100 mg tablet
            Norvir oral
            -
            100 mg powder
            Norvir oral
            -
            80 mg/mL solution
            ritonavir oral
            -
            100 mg tablet
            ritonavir oral
            -
            100 mg tablet
            ritonavir oral
            -
            100 mg tablet
            ritonavir oral
            -
            100 mg tablet

            Copyright © 2010 First DataBank, Inc.

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            Patient Handout

            Patient Education
            ritonavir oral

            RITONAVIR - ORAL

            (rye-TAWN-uh-veer)

            COMMON BRAND NAME(S): Norvir

            WARNING: Ritonavir may interact with many different types of medicines, in some cases causing severe (sometimes fatal) reactions. Consult your doctor or pharmacist about which medications should not be taken with ritonavir. (See also Drug Interactions section.)

            USES: This drug is used with other HIV medications to help control HIV infection. It helps to decrease the amount of HIV in your body so your immune system can work better. This lowers your chance of getting HIV complications (such as new infections, cancer) and improves your quality of life.Ritonavir belongs to a class of drugs known as protease inhibitors. It increases ("boosts") the levels of other protease inhibitors, which helps these medications work better.Ritonavir is not a cure for HIV infection. To decrease your risk of spreading HIV disease to others, continue to take all HIV medications exactly as prescribed by your doctor. Use an effective barrier method (latex or polyurethane condoms/dental dams) during sexual activity as directed by your doctor. Do not share personal items (such as needles/syringes, toothbrushes, and razors) that may have contacted blood or other body fluids. Consult your doctor or pharmacist for more details.

            HOW TO USE: Read the Patient Information Leaflet provided by your pharmacist before you start taking ritonavir and each time you get a refill. If you have any questions, consult your doctor or pharmacist.Take this medication by mouth with a meal as directed by your doctor, usually 1 to 2 times daily. Take ritonavir at the same time(s) as your other HIV protease inhibitor. Swallow the tablet form of this medication whole. Do not crush, chew, or break the tablets.The dosage is based on your medical condition, response to treatment, and other medications you may be taking. Be sure to tell your doctor and pharmacist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products). For children, the dosage may also be based on their body size.For the best effect, take this medication at evenly spaced times. To help you remember, take this medication at the same time(s) every day.The tablet and capsule forms of this medication may deliver different amounts of medication. Do not switch between the tablet and capsule forms without your doctor's permission and directions.It is very important to continue taking this medication (and other HIV medications) exactly as prescribed by your doctor. Do not take more or less of this drug than prescribed or stop taking it (or other HIV medicines) even for a short time unless directed to do so by your doctor. Skipping or changing your dose without approval from your doctor may cause the amount of virus to increase, make the infection more difficult to treat, or worsen side effects.

            SIDE EFFECTS: Diarrhea, nausea, vomiting, heartburn, stomach pain, dizziness, tiredness, weakness, changes in taste, or tingling/numbness of mouth area may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.As your immune system gets stronger, it can begin to fight off infections you already had, possibly causing disease symptoms to come back. You could also have symptoms if your immune system becomes overactive. This reaction may happen at any time (soon after starting HIV treatment or many months later). Get medical help right away if you have any serious symptoms, including: unexplained weight loss, severe tiredness, muscle aches/weakness that doesn't go away, headaches that are severe or don't go away, joint pain, numbness/tingling of the hands/feet/arms/legs, vision changes, signs of infection (such as fever, chills, swollen lymph nodes, trouble breathing, cough, non-healing skin sores), signs of an overactive thyroid (such as irritability, nervousness, heat intolerance, fast/pounding/irregular heartbeat, bulging eyes, unusual growth in the neck/thyroid known as a goiter), signs of a certain nerve problem known as Guillain-Barre syndrome (such as trouble breathing/swallowing/moving your eyes, drooping face, paralysis, trouble speaking).Tell your doctor right away if you have any serious side effects, including: persistent nausea/vomiting, stomach/abdominal pain, dark urine, loss of appetite, yellowing eyes/skin, mental/mood changes (such as depression, anxiety), increased urination (especially at night), increased thirst.Get medical help right away if you have any very serious side effects, including: symptoms of a heart attack (such as chest/jaw/left arm pain, shortness of breath, unusual sweating), easy bruising/bleeding, fainting, fast/irregular heartbeat.Changes in body fat may occur while you are taking this medication (such as increased fat in the upper back and stomach areas, decreased fat in the arms and legs). The cause and long-term effects of these changes are unknown. Discuss the risks and benefits of treatment with your doctor, as well as the possible use of exercise to reduce this side effect.A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.In the US -Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

            PRECAUTIONS: Before taking ritonavir, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.Before using this medication, tell your doctor or pharmacist your medical history, especially of: diabetes, heart problems (coronary artery disease, heart attack), hemophilia, high cholesterol/triglycerides, liver problems (such as hepatitis B, hepatitis C), pancreatitis.This drug may make you dizzy. Alcohol or marijuana (cannabis) can make you more dizzy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).If you have diabetes, this product may increase your blood sugar. Check your blood sugar regularly as directed and share the results with your doctor. Tell your doctor right away if you have symptoms of high blood sugar such as increased thirst/urination. Your doctor may need to adjust your diabetes medication, exercise program, or diet.Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).Tell your doctor if you are pregnant before using this medication. Treatment can lower the risk of passing HIV infection to your baby. Discuss the risks and benefits with your doctor.This medication passes into breast milk. Because breast milk can transmit HIV, do not breast-feed.

            DRUG INTERACTIONS: Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.Ritonavir interacts with many medications. Some products that may interact with this drug include: cobicistat, disulfiram, orlistat.Ritonavir can slow down or speed up the removal of other medications from your body, which may affect how they work. Examples of affected drugs include alfuzosin, antiarrhythmics (such as amiodarone, flecainide, propafenone, quinidine), azole antifungals (such as voriconazole), certain benzodiazepines (midazolam, triazolam), certain "blood thinners" (such as rivaroxaban, warfarin), cisapride, eletriptan, drugs to treat erectile dysfunction-ED or pulmonary hypertension (such as avanafil, sildenafil), ergot alkaloids (such as dihydroergotamine, ergonovine, ergotamine, methylergonovine), lurasidone, certain opioid pain medications (such as fentanyl, meperidine), pimozide, ranolazine, salmeterol, simeprevir, "statin" cholesterol drugs (such as simvastatin, lovastatin), among others.Other medications can affect the removal of ritonavir from your body, which may affect how ritonavir works. Examples include apalutamide, boceprevir, rifampin, St. John's wort, among others.This medication may decrease the effectiveness of hormonal birth control such as pills, patch, or ring. This could cause pregnancy. Talk to your doctor about additional or alternative reliable forms of birth control, and use an effective barrier method (latex or polyurethane condoms/dental dams) during sexual activity to decrease the risk of spreading HIV to others. Tell your doctor if you have any new spotting or breakthrough bleeding, because these may be signs that your hormonal birth control is not working well.

            OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center.

            NOTES: Do not share this medication with others.Laboratory and/or medical tests (such as liver tests, viral load, T-cell counts, triglycerides/cholesterol, blood sugar) should be performed periodically to monitor your progress or check for side effects. Consult your doctor for more details.Keep all medical and laboratory appointments.

            MISSED DOSE: If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.

            STORAGE: Store the capsule form of this medication in the refrigerator away from light. Do not freeze. The capsules may also be stored at room temperature. If stored at room temperature, use within 30 days.Store the tablet form of this medication at room temperature away from light and moisture.Do not store in the bathroom. Keep all medications away from children and pets.Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.

            Information last revised January 2021. Copyright(c) 2021 First Databank, Inc.

            IMPORTANT: HOW TO USE THIS INFORMATION: This is a summary and does NOT have all possible information about this product. This information does not assure that this product is safe, effective, or appropriate for you. This information is not individual medical advice and does not substitute for the advice of your health care professional. Always ask your health care professional for complete information about this product and your specific health needs.

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            Formulary

            FormularyPatient Discounts

            Adding plans allows you to compare formulary status to other drugs in the same class.

            To view formulary information first create a list of plans. Your list will be saved and can be edited at any time.

            Adding plans allows you to:

            • View the formulary and any restrictions for each plan.
            • Manage and view all your plans together – even plans in different states.
            • Compare formulary status to other drugs in the same class.
            • Access your plan list on any device – mobile or desktop.

            The above information is provided for general informational and educational purposes only. Individual plans may vary and formulary information changes. Contact the applicable plan provider for the most current information.

            Tier Description
            1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
            2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
            3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
            4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            6 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            NC NOT COVERED – Drugs that are not covered by the plan.
            Code Definition
            PA Prior Authorization
            Drugs that require prior authorization. This restriction requires that specific clinical criteria be met prior to the approval of the prescription.
            QL Quantity Limits
            Drugs that have quantity limits associated with each prescription. This restriction typically limits the quantity of the drug that will be covered.
            ST Step Therapy
            Drugs that have step therapy associated with each prescription. This restriction typically requires that certain criteria be met prior to approval for the prescription.
            OR Other Restrictions
            Drugs that have restrictions other than prior authorization, quantity limits, and step therapy associated with each prescription.
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            Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.