efavirenz (Rx)

Brand and Other Names:Sustiva
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Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

capsule

  • 50mg
  • 200mg

tablet

  • 600mg

HIV Infection

Indicated in combination with other antiretroviral agents for HIV-1 infection

600 mg PO qDay; used in combination with protease inhibitor and/or NRTIs

Dosage Modifications

Coadministration with voriconazole: Increase voriconazole maintenance dose to 400 mg q12hr and decrease efavirenz dose to 300 mg qDay (using capsule formulation)

Coadministration with rifampin: If weight >50 kg, increase efavirenz to 800 mg qDay

Renal impairment: No dosage adjustment needed

Hepatic impairment

  • Mild (Child-Pugh Class A): Dose adjustment not necessary; use caution
  • Moderate-to-severe (Child Pugh Class B or C): Not recommended

Dosage Forms & Strengths

capsule

  • 50mg
  • 200mg

tablet

  • 600mg

HIV Infection

NOTE: The NIH pediatric HIV treatment guideline (March 2016) differs from the prescribing information and recommends that efavirenz generally should NOT be used in children aged <3 yr

Indicated in combination with other antiretroviral agents for HIV-1 infection in pediatric patients >3 months old and weighing ≥3.5 kg

<3 months: Safety and efficacy not established

≥3 months (prescribing information)

  • 3.5 kg to <5 kg: 100 mg PO qDay
  • 5 to <7.5 kg: 150 mg PO qDay
  • 7.5 to <15 kg: 200 mg PO qDay
  • 15 to <20 kg: 250 mg PO qDay
  • 20 to <25 kg: 300 mg PO qDay
  • 25 to <32.5 kg: 350 mg PO qDay
  • 32.5 to <40 kg: 400 mg PO qDay
  • ≥40 kg: 600 mg PO qDay

NIH pediatric HIV treatment guidelines (March 2016)

  • Investigational dosing for 3 months to <3 years based on CYP 2B6 genotype
  • Extensive metabolizers (ie, CYP 2B6 516 GG and GT genotype)
    • 3 to <5 kg: 200 mg PO qDay
    • 5 to <7 kg: 300 mg PO qDay
    • 7 to <14 kg: 400 mg PO qDay
    • 14 to <17 kg: 500 mg PO qDay
    • ≥17 kg: 600 mg PO qDay
  • Slow metabolizers (ie, CYP 2B6 516 TT genotype)
    • 3 to <7 kg: 50 mg PO qDay
    • 7 to <14 kg: 100 mg PO qDay
    • ≥14kg: 150 mg PO qDay
  • ≥3 years
    • 10 to <15 kg: 200 mg PO qDay
    • 15 to <20 kg: 250 mg PO qDay
    • 20 to <25 kg: 300 mg PO qDay
    • 25 to <32.5 kg: 350 mg PO qDay
    • 32.5 to <40 kg: 400 mg PO qDay
    • ≥40 kg: 600 mg PO qDay

Dosage Modifications

Coadministration with voriconazole: If weight >40 kg and age >12 yr, increase voriconazole maintenance dose to 400 mg q12hr and decrease efavirenz dose to 300 mg qDay (using capsule formulation)

Coadministration with rifampin: If weight >40 kg, increase efavirenz to 800 mg qDay

Renal impairment: No dosage adjustment needed

Hepatic impairment

  • Mild (Child-Pugh Class A): Dose adjustment not necessary; use caution
  • Moderate-to-severe (Child Pugh Class B or C): Not recommended
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Interactions

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            Contraindicated (26)

            • carbamazepine

              carbamazepine, efavirenz. Either decreases levels of the other by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Coadministration of carbamazepine with NNRTIs may result in a loss of virologic response and possible resistance to the NNRTI. A decrease in AUC is observed for both carbamazepine (27%) and efavirenz (36%) when coadministered.

            • cariprazine

              efavirenz will decrease the level or effect of cariprazine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. CYP3A4 is responsible for the formation and elimination of cariprazine's active metabolites. The effect of CYP3A4 inducers on cariprazine exposure has not been evaluated and the net effect is unclear.

            • cobimetinib

              efavirenz will decrease the level or effect of cobimetinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Avoid coadministration. Strong or moderate CYP3A inducers may decrease cobimetinib systemic exposure by >80% and reduce its efficacy.

            • dienogest/estradiol valerate

              efavirenz will decrease the level or effect of dienogest/estradiol valerate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Women should not choose estradiol valerate/dienogest as their contraceptive while using strong CYP3A4 inducers due to potential decrease in contraceptive efficacy. Estradiol valerate/dienogest should not be used for at least 28 days after discontinuation of the inducer due to possibility of decreased contraceptive efficacy.

            • doravirine

              efavirenz will decrease the level or effect of doravirine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Coadministration of doravirine with a strong CYP3A inducer may decrease doravirine plasma concentrations and/or effects. Potential for loss of virologic response and possible resistance to doravirine.

            • dronedarone

              efavirenz and dronedarone both increase QTc interval. Contraindicated.

            • elbasvir/grazoprevir

              efavirenz will decrease the level or effect of elbasvir/grazoprevir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. The therapeutic effect of elbasvir/grazoprevir may be reduced if coadministered with strong CYP3A inducers and is therefore contraindicated.

            • elvitegravir/cobicistat/emtricitabine/tenofovir DF

              efavirenz, 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.

            • ergonovine

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

            • etravirine

              efavirenz decreases levels of etravirine by increasing metabolism. Contraindicated. Mfr.'s PI recommends not combining etravirine with other NNRTIs.

            • fostemsavir

              efavirenz will decrease the level or effect of fostemsavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Coadministration of fostemsavir (prodrug) with strong CYP3A4 inducers significantly decreases temsavir (active moiety) plasma concentrations, which may lead to loss of virologic response and resistance.

            • isavuconazonium sulfate

              efavirenz will decrease the level or effect of isavuconazonium sulfate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

            • lefamulin

              lefamulin will increase the level or effect of efavirenz by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Lefamulin is contraindicated with CYP3A substrates know to prolong the QT interval.

            • lomitapide

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

            • lonafarnib

              efavirenz will decrease 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 inducers is contraindicated.

            • lorlatinib

              efavirenz will decrease the level or effect of lorlatinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Coadministration of lorlatinib with strong CYP3A inducers is contraindicated. Discontinue the strong CYP3A inducer for 3 plasma half-lives before initiating lorlatinib.

            • lumacaftor/ivacaftor

              efavirenz will decrease the level or effect of lumacaftor/ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Strong CYP3A inducers have minimal effect on lumacaftor exposure, but decreased ivacaftor exposure (AUC) by 57%. This may reduce the effectiveness of lumacaftor/ivacaftor. Therefore, coadministration is not recommended.

            • nevirapine

              efavirenz and nevirapine both increase risk of immune reconstitution syndrome. Contraindicated. Coadministration not recommended as this combination has been associated with an increase in adverse reactions and no improvement in efficacy

            • ombitasvir/paritaprevir/ritonavir

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

            • ombitasvir/paritaprevir/ritonavir & dasabuvir (DSC)

              ombitasvir/paritaprevir/ritonavir & dasabuvir (DSC), efavirenz. unspecified interaction mechanism. Contraindicated. Coadministration of avirenz-based regimens with Viekira Pak was poorly tolerated and resulted in liver enzyme elevations.

              efavirenz will decrease the level or effect of ombitasvir/paritaprevir/ritonavir & dasabuvir (DSC) by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

            • panobinostat

              efavirenz decreases levels of panobinostat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Strong CYP3A4 inducers can reduce panobinostat levels by ~70% and lead to treatment failure.

            • posaconazole

              efavirenz and posaconazole both increase QTc interval. Contraindicated.

            • praziquantel

              efavirenz decreases levels of praziquantel by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Strong CYP450 inducers significantly decrease praziquantel blood levels.

            • ranolazine

              efavirenz and ranolazine both increase QTc interval. Contraindicated.

            • rilpivirine

              efavirenz decreases levels of rilpivirine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Contraindicated. Rilpivirine should not be used in combination with NNRTIs.

            • voriconazole

              voriconazole will increase the level or effect of efavirenz by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Contraindication applies to efavirenz doses of 400 mg/day or higher. This dose of efavirenz induces CYP3A4 resulting in decreased voriconazole levels. When voriconazole is coadministered with efavirenz, voriconazole oral maintenance dose should be increased to 400 mg q12hr and efavirenz should be decreased to 300 mg q24hr.

              efavirenz decreases effects of voriconazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Contraindication applies to efavirenz doses of 400 mg/day or higher. This dose of efavirenz induces CYP3A4 resulting in decreased voriconazole levels. When voriconazole is coadministered with efavirenz, voriconazole oral maintenance dose should be increased to 400 mg q12hr and efavirenz should be decreased to 300 mg q24hr.

            Serious - Use Alternative (203)

            • abametapir

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

              abametapir will increase the level or effect of efavirenz by affecting hepatic enzyme CYP2B6 metabolism. Avoid or Use Alternate Drug. For 2 weeks after abametapir application, avoid taking drugs that are CYP2B6 substrates. If not feasible, avoid use of abametapir.

            • abemaciclib

              efavirenz will decrease the level or effect of abemaciclib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of abemaciclib with strong CYP3A4 inducers reduces plasma concentration of abemaciclib and its metabolites.

            • alfuzosin

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

            • alpelisib

              efavirenz will decrease the level or effect of alpelisib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of alpelisib (CYP3A4 substrate) with strong CYP3A4 inducers.

            • amiodarone

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

              efavirenz and amiodarone both increase QTc interval. Avoid or Use Alternate Drug.

            • amisulpride

              efavirenz and amisulpride both increase QTc interval. Avoid or Use Alternate Drug. ECG monitoring is recommended if coadministered.

            • anagrelide

              efavirenz and anagrelide both increase QTc interval. Avoid or Use Alternate Drug.

            • apalutamide

              apalutamide will decrease the level or effect of efavirenz 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.

              efavirenz will decrease the level or effect of apalutamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. No initial dose adjustment

            • apremilast

              efavirenz will decrease the level or effect of apremilast by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration with strong CYP inducers results in a significant decrease of systemic exposure of apremilast, which may result in loss of efficacy

            • artemether

              efavirenz and artemether both increase QTc interval. Avoid or Use Alternate Drug.

            • artemether/lumefantrine

              efavirenz will decrease the level or effect of artemether/lumefantrine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration with strong CYP3A4 inducers can result in decreased serum concentrations and loss of antimalarial efficacy

              efavirenz and artemether/lumefantrine both increase QTc interval. Avoid or Use Alternate Drug.

            • asenapine

              efavirenz and asenapine both increase QTc interval. Avoid or Use Alternate Drug.

            • atazanavir

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

            • atovaquone

              efavirenz decreases levels of atovaquone by unspecified interaction mechanism. Avoid or Use Alternate Drug.

            • axitinib

              efavirenz decreases levels of axitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Selection of concomitant medication with no or minimal CYP3A4 induction potential is recommended.

            • azithromycin

              efavirenz and azithromycin both increase QTc interval. Avoid or Use Alternate Drug.

            • bedaquiline

              efavirenz will decrease 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 inducers due to potential for decreased therapeutic effect

              efavirenz and bedaquiline both increase QTc interval. Avoid or Use Alternate Drug.

            • bosutinib

              efavirenz decreases levels of bosutinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Strong CYP3A4 inducers decreased bosutinib plasma concentration by ~85% .

            • brigatinib

              efavirenz will decrease the level or effect of brigatinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration with strong CYP3A4 inducers may decrease brigatinib efficacy.

            • bromocriptine

              efavirenz increases levels of bromocriptine by decreasing metabolism. Avoid or Use Alternate Drug. Competitive inhibition of CYP3A4 might lead to vasospasm and ischemia.

            • buprenorphine

              efavirenz and buprenorphine both increase QTc interval. Avoid or Use Alternate Drug.

            • buprenorphine transdermal

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

            • cabergoline

              efavirenz increases levels of cabergoline by decreasing metabolism. Avoid or Use Alternate Drug. Competitive inhibition of CYP3A4 might lead to vasospasm and ischemia.

            • cabotegravir

              efavirenz, 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

              efavirenz will decrease 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 inducers. If a strong CYP3A4 inducer is required, increase cabozantinib dose by 40 mg/day (Cometriq) or by 20 mg/day (Cabometyx). Resume previous dose 2-3 days after strong CYP3A4 inducer discontinued.

            • capmatinib

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

            • carvedilol

              efavirenz will increase the level or effect of carvedilol by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug.

            • ceritinib

              efavirenz decreases levels of ceritinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

              efavirenz and ceritinib both increase QTc interval. Avoid or Use Alternate Drug.

            • chloroquine

              efavirenz and chloroquine both increase QTc interval. Avoid or Use Alternate Drug.

            • chlorpromazine

              efavirenz and chlorpromazine both increase QTc interval. Avoid or Use Alternate Drug.

            • citalopram

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

              efavirenz and citalopram both increase QTc interval. Avoid or Use Alternate Drug.

            • clarithromycin

              efavirenz and clarithromycin both increase QTc interval. Avoid or Use Alternate Drug.

            • clopidogrel

              efavirenz decreases effects of clopidogrel by affecting hepatic enzyme CYP2C19 metabolism. Avoid or Use Alternate Drug. Clopidogrel efficacy may be reduced by drugs that inhibit CYP2C19. Inhibition of platelet aggregation by clopidogrel is entirely due to an active metabolite. Clopidogrel is metabolized to this active metabolite in part by CYP2C19. .

            • cobicistat

              efavirenz will decrease the level or effect of cobicistat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration with efavirenz may result in loss of therapeutic effect and development of resistance to cobicistat.

            • copanlisib

              efavirenz will decrease the level or effect of copanlisib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of copanlisib with strong CYP3A4 inducers.

            • crizotinib

              efavirenz and crizotinib both increase QTc interval. Avoid or Use Alternate Drug.

            • dabrafenib

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

            • daridorexant

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

            • darolutamide

              efavirenz will decrease the level or effect of darolutamide by Other (see comment). Avoid or Use Alternate Drug. Darolutamide is a P-gp and CYP3A4 substrate. Avoid coadminstration of darolutamide with combined P-gp and strong or moderate CYP3A4 inducers.

            • darunavir

              efavirenz will decrease the level or effect of darunavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration with efavirenz may result in loss of therapeutic effect and development of resistance to darunavir

            • deflazacort

              efavirenz will decrease the level or effect of deflazacort by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of deflazacort with moderate or strong CYP3A4 inducers.

            • dihydroergotamine

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

            • dihydroergotamine intranasal

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

            • disopyramide

              efavirenz and disopyramide both increase QTc interval. Avoid or Use Alternate Drug.

            • dofetilide

              efavirenz and dofetilide both increase QTc interval. Avoid or Use Alternate Drug.

            • dolutegravir

              efavirenz will decrease the level or effect of dolutegravir by increasing metabolism. Avoid or Use Alternate Drug. Increase dolutegravir dose to 50 mg BID when coadministered with strong UGT1A/CYP3A inducers

            • dronedarone

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

            • droperidol

              efavirenz and droperidol both increase QTc interval. Avoid or Use Alternate Drug.

            • duvelisib

              efavirenz will decrease the level or effect of duvelisib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration with a strong CYP3A inducer decreases duvelisib area under the curve (AUC), which may reduce duvelisib efficacy.

            • eletriptan

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

            • eltrombopag

              efavirenz will increase the level or effect of eltrombopag by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug.

            • elvitegravir

              efavirenz will decrease the level or effect of elvitegravir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid; coadministration with CYP3A inducers may result in decreased plasma concentrations of elvitegravir and/or a concomitantly administered protease inhibitor and lead to loss of therapeutic effect and to possible resistance

            • elvitegravir/cobicistat/emtricitabine/tenofovir DF

              efavirenz will decrease the level or effect of elvitegravir/cobicistat/emtricitabine/tenofovir DF by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • encorafenib

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

              efavirenz and encorafenib both increase QTc interval. Avoid or Use Alternate Drug.

              encorafenib and efavirenz both increase QTc interval. Avoid or Use Alternate Drug.

            • entrectinib

              efavirenz and entrectinib both increase QTc interval. Avoid or Use Alternate Drug.

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

            • enzalutamide

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

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

            • erdafitinib

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

              efavirenz will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

            • ergoloid mesylates

              efavirenz increases levels of ergoloid mesylates by decreasing metabolism. Avoid or Use Alternate Drug. Competitive inhibition of CYP3A4 might lead to vasospasm and ischemia.

            • ergotamine

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

              efavirenz increases levels of ergotamine by decreasing metabolism. Avoid or Use Alternate Drug. Competitive inhibition of CYP3A4 might lead to vasospasm and ischemia.

            • eribulin

              efavirenz and eribulin both increase QTc interval. Avoid or Use Alternate Drug.

            • erythromycin base

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

              efavirenz and erythromycin base both increase QTc interval. Avoid or Use Alternate Drug.

            • erythromycin ethylsuccinate

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

              efavirenz and erythromycin ethylsuccinate both increase QTc interval. Avoid or Use Alternate Drug.

            • erythromycin lactobionate

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

              efavirenz and erythromycin lactobionate both increase QTc interval. Avoid or Use Alternate Drug.

            • erythromycin stearate

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

              efavirenz and erythromycin stearate both increase QTc interval. Avoid or Use Alternate Drug.

            • ethinylestradiol

              efavirenz will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

            • ethotoin

              efavirenz will increase the level or effect of ethotoin by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug.

            • etravirine

              efavirenz will increase the level or effect of etravirine by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug.

            • everolimus

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

            • fedratinib

              efavirenz will decrease the level or effect of fedratinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Effect of coadministering a strong CYP3A4 inducer with fedratinib has not been studied.

            • fexinidazole

              efavirenz will increase the level or effect of fexinidazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. CYP450 inducers may significantly increase plasma concentrations of fexinidazole?s active metabolites: fexinidazole sulfoxide (M1) and fexinidazole sulfone (M2). M2 plasma concentrations associated with increased QT prolongation risks.

              fexinidazole will decrease the level or effect of efavirenz by affecting hepatic enzyme CYP2B6 metabolism. Avoid or Use Alternate Drug. Coadministration may decrease plasma concentrations of CYP2B6 substrates owing to fexinidazole inducing CYP2B6.

              fexinidazole and efavirenz both increase QTc interval. Avoid or Use Alternate Drug. Avoid coadministration of fexinidazole with drugs known to block potassium channels or prolong QT interval.

              fexinidazole will increase the level or effect of efavirenz by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Fexinidazole inhibits CYP3A4. Coadministration may increase risk for adverse effects of CYP3A4 substrates.

            • finerenone

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

            • fingolimod

              fingolimod and efavirenz both increase QTc interval. Avoid or Use Alternate Drug.

            • flecainide

              efavirenz and flecainide both increase QTc interval. Avoid or Use Alternate Drug.

            • foscarnet

              efavirenz and foscarnet both increase QTc interval. Avoid or Use Alternate Drug.

            • fosphenytoin

              efavirenz will increase the level or effect of fosphenytoin by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug.

            • fostamatinib

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

            • gemtuzumab

              efavirenz and gemtuzumab both increase QTc interval. Avoid or Use Alternate Drug.

            • glasdegib

              efavirenz will decrease the level or effect of glasdegib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of glasdegib with strong CYP3A inducers.

              efavirenz and glasdegib both increase QTc interval. Avoid or Use Alternate Drug. If coadministration unavoidable, monitor for increased risk of QTc interval prolongation.

            • glecaprevir/pibrentasvir

              efavirenz will decrease the level or effect of glecaprevir/pibrentasvir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of efavirenz (a strong CYP3A4 inducer) with glecaprevir/pibrentasvir may significantly decrease glecaprevir/pibrentasvir plasma concentrations and AUC. Potential for loss of therapeutic effect.

            • hydroxychloroquine sulfate

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

            • ibrutinib

              efavirenz decreases levels of ibrutinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Strong CYP3A inducers decrease ibrutinib plasma concentrations by ~10-fold.

            • ibutilide

              efavirenz and ibutilide both increase QTc interval. Avoid or Use Alternate Drug.

            • idelalisib

              efavirenz will decrease the level or effect of idelalisib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration; strong CYP3A4 inducers significantly decrease idelalisib systemic exposure

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

            • iloperidone

              efavirenz and iloperidone both increase QTc interval. Avoid or Use Alternate Drug.

            • indinavir

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

            • infigratinib

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

            • inotuzumab

              efavirenz and inotuzumab both increase QTc interval. Avoid or Use Alternate Drug.

            • irinotecan

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

            • irinotecan liposomal

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

            • isoflurane

              efavirenz and isoflurane both increase QTc interval. Avoid or Use Alternate Drug.

            • istradefylline

              efavirenz will decrease the level or effect of istradefylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of istradefylline with strong CYP3A4 inducers.

            • itraconazole

              itraconazole will increase the level or effect of efavirenz by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Not recommended 2 weeks before and during itraconazole.

              efavirenz will decrease the level or effect of itraconazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Not recommended 2 weeks before and during itraconazole.

              efavirenz and itraconazole both increase QTc interval. Avoid or Use Alternate Drug.

            • ivabradine

              efavirenz will decrease the level or effect of ivabradine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of ivabradine with moderate CYP3A4 inducers.

            • ivacaftor

              efavirenz, ivacaftor. Other (see comment). Avoid or Use Alternate Drug. Comment: Efavirenz decreases levels of ivacaftor by CYP enzyme induction; whereas, ivacaftor increases levels of efavirenz by inhibiting CYP3A4 .

            • ivosidenib

              efavirenz will decrease the level or effect of ivosidenib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of ivosidenib with strong CYP3A4 inducers decreased ivosidenib plasma concentrations.

              efavirenz and ivosidenib both decrease QTc interval. Avoid or Use Alternate Drug.

            • ixazomib

              efavirenz will decrease the level or effect of ixazomib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of ixazomib with strong CYP3A inducers. Strong inducers have been shown to decrease ixazomib Cmax by 54% and AUC by 74%.

            • larotrectinib

              efavirenz will decrease 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 inducers is unavoidable, double larotrectinib dose. Resume prior larotrectinib dose once CYP3A4 inducer discontinued for 3-5 half-lives

            • lefamulin

              efavirenz and lefamulin both increase QTc interval. Avoid or Use Alternate Drug.

            • lemborexant

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

            • lenvatinib

              efavirenz and lenvatinib both increase QTc interval. Avoid or Use Alternate Drug.

            • letermovir

              efavirenz will decrease the level or effect of letermovir by Other (see comment). Avoid or Use Alternate Drug. Coadministration of letermovir with UCT1A1/3 inducers is not recommended.

            • lofexidine

              efavirenz and lofexidine both increase QTc interval. Avoid or Use Alternate Drug.

            • lopinavir

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

              efavirenz and lopinavir both increase QTc interval. Avoid or Use Alternate Drug.

            • lorlatinib

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

            • lovastatin

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

            • lumefantrine

              efavirenz will decrease the level or effect of lumefantrine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration with strong CYP3A4 inducers can result in decreased serum concentrations and loss of antimalarial efficacy

            • lurbinectedin

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

            • macimorelin

              efavirenz will decrease the level or effect of macimorelin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Potential for false positive test results if macimorelin and strong CYP3A4 inducers are coadministered. Discontinue strong CYP3A4 inducer, allowing for sufficient washout time, before testing.

              efavirenz and macimorelin both increase QTc interval. Avoid or Use Alternate Drug.

            • macitentan

              efavirenz will decrease the level or effect of macitentan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministering macitentan with strong CYP3A4 inducers

            • methadone

              efavirenz and methadone both increase QTc interval. Avoid or Use Alternate Drug.

            • methylergonovine

              efavirenz increases levels of methylergonovine by decreasing metabolism. Avoid or Use Alternate Drug. Competitive inhibition of CYP3A4 might lead to vasospasm and ischemia.

            • metoclopramide intranasal

              efavirenz, metoclopramide intranasal. Either increases effects of the other by Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid use of metoclopramide intranasal or interacting drug, depending on importance of drug to patient.

            • midostaurin

              efavirenz will decrease the level or effect of midostaurin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Strong CYP3A4 inducers may decrease midostaurin concentrations resulting in reduced efficacy.

              efavirenz and midostaurin both increase QTc interval. Avoid or Use Alternate Drug.

            • mifepristone

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

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

              efavirenz and mifepristone both increase QTc interval. Avoid or Use Alternate Drug.

            • mobocertinib

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

              efavirenz and mobocertinib both increase QTc interval. Avoid or Use Alternate Drug.

            • moxifloxacin

              efavirenz and moxifloxacin both increase QTc interval. Avoid or Use Alternate Drug.

            • naloxegol

              efavirenz will decrease the level or effect of naloxegol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Use of naloxegol with strong CYP3A4 inducers is not recommended

            • nateglinide

              efavirenz will increase the level or effect of nateglinide by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug.

            • nefazodone

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

            • neratinib

              efavirenz will decrease 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 inducers.

            • netupitant/palonosetron

              efavirenz will decrease the level or effect of netupitant/palonosetron by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Netupitant is mainly metabolized by CYP3A4; avoid use in patients who are chronically using a strong CYP3A4 inducer

            • nevirapine

              nevirapine will decrease the level or effect of efavirenz by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration not recommended as this combination has been associated with an increase in adverse reactions and no improvement in efficacy

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

            • nilotinib

              efavirenz and nilotinib both increase QTc interval. Avoid or Use Alternate Drug.

            • nisoldipine

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

            • norethindrone

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

            • norgestrel

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

            • olaparib

              efavirenz will decrease the level or effect of olaparib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with moderate CYP3A inducers cannot be avoided, be aware of a potential for decreased efficacy of olaparib

            • ondansetron

              efavirenz and ondansetron both increase QTc interval. Avoid or Use Alternate Drug.

            • osimertinib

              efavirenz will decrease the level or effect of osimertinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid concomitant use of osimertinib with strong CYP3A inducers.

              efavirenz and osimertinib both increase QTc interval. Avoid or Use Alternate Drug.

            • oxaliplatin

              efavirenz and oxaliplatin both increase QTc interval. Avoid or Use Alternate Drug.

            • ozanimod

              efavirenz and ozanimod both increase QTc interval. Avoid or Use Alternate Drug.

            • panobinostat

              efavirenz and panobinostat both increase QTc interval. Avoid or Use Alternate Drug.

            • parecoxib

              efavirenz will increase the level or effect of parecoxib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug.

            • pazopanib

              efavirenz and pazopanib both increase QTc interval. Avoid or Use Alternate Drug.

            • pemigatinib

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

            • pentamidine

              efavirenz and pentamidine both increase QTc interval. Avoid or Use Alternate Drug.

            • perampanel

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

            • pexidartinib

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

              efavirenz and pexidartinib both increase Other (see comment). Avoid or Use Alternate Drug. Pexidartinib can cause hepatotoxicity. Avoid coadministration of pexidartinib with other products know to cause hepatoxicity.

            • pimavanserin

              efavirenz and pimavanserin both increase QTc interval. Avoid or Use Alternate Drug.

            • pimozide

              efavirenz and pimozide both increase QTc interval. Contraindicated.

            • pitolisant

              efavirenz and pitolisant both increase QTc interval. Avoid or Use Alternate Drug.

            • pomalidomide

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

            • ponesimod

              efavirenz and ponesimod both increase QTc interval. Avoid or Use Alternate Drug.

            • pralsetinib

              efavirenz will decrease the level or effect of pralsetinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid, double current pralsetinib dose starting on Day 7 of coadministration with strong CYP3A inducer. After inducer has been discontinued for at least 14 days, resume previous pralsetinib dose.

            • pretomanid

              efavirenz will decrease the level or effect of pretomanid by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. CYP3A4 substrate. Avoid coadministration of strong or moderate CYP3A4 inducers.

              efavirenz, pretomanid. Either increases toxicity of the other by Other (see comment). Avoid or Use Alternate Drug. Comment: Pretomanid regimen associated with hepatotoxicity. Avoid alcohol and hepatotoxic agents, including herbal supplements and drugs other than bedaquiline and linezolid.

            • procainamide

              efavirenz and procainamide both increase QTc interval. Avoid or Use Alternate Drug.

            • propafenone

              efavirenz and propafenone both increase QTc interval. Avoid or Use Alternate Drug.

            • quetiapine

              efavirenz and quetiapine both increase QTc interval. Avoid or Use Alternate Drug.

            • quinidine

              efavirenz and quinidine both increase QTc interval. Avoid or Use Alternate Drug.

            • quinine

              efavirenz and quinine both increase QTc interval. Avoid or Use Alternate Drug.

            • ranolazine

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

            • regorafenib

              efavirenz will decrease the level or effect of regorafenib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Strong CYP3A4 inducers decrease regorafenib levels and increase exposure of the active metabolite M-5

            • ribociclib

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

              efavirenz and ribociclib both increase QTc interval. Avoid or Use Alternate Drug.

            • rifabutin

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

            • rilpivirine

              efavirenz and rilpivirine both increase QTc interval. Avoid or Use Alternate Drug.

            • rimegepant

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

            • ripretinib

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

            • risperidone

              efavirenz and risperidone both increase QTc interval. Avoid or Use Alternate Drug.

            • rolapitant

              efavirenz will decrease the level or effect of rolapitant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Long-term coadministration of strong CYP3A4 inducers with rolapitant may significantly decrease rolapitant efficacy.

            • ropeginterferon alfa 2b

              ropeginterferon alfa 2b and efavirenz both increase Other (see comment). Avoid or Use Alternate Drug. Narcotics, hypnotics or sedatives can produce additive neuropsychiatric side effects. Avoid use and monitor patients receiving the combination for effects of excessive CNS toxicity.

            • saquinavir

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

              efavirenz and saquinavir both increase QTc interval. Avoid or Use Alternate Drug.

            • selpercatinib

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

              efavirenz and selpercatinib both increase QTc interval. Avoid or Use Alternate Drug.

            • selumetinib

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

            • sevoflurane

              efavirenz and sevoflurane both increase QTc interval. Avoid or Use Alternate Drug.

            • silodosin

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

            • siponimod

              efavirenz will increase the level or effect of siponimod by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. Coadministration of siponimod with drugs that cause moderate CYP2C9 AND a moderate or strong CYP3A4 inhibition is not recommended. Caution if siponimod coadministered with moderate CYP2C9 inhibitors alone.

              efavirenz will decrease the level or effect of siponimod by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of siponimod with a drug that causes moderate CYP2C9 plus a moderate or strong CYP3A4 inducer is not recommended. Coadministration with moderate or strong CYP3A4 inducers alone is not recommended for patients with CYP2C9*1/*3 and*2/*3 genotype.

              efavirenz and siponimod both increase QTc interval. Avoid or Use Alternate Drug.

            • sirolimus

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

            • sofosbuvir/velpatasvir

              efavirenz will decrease the level or effect of sofosbuvir/velpatasvir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Velpatasvir is a substrate of CYP2B6, CYP2C8, and CYP3A4. Drugs that are moderate-to-potent inducers of CYP2B6, CYP2C8, or CYP3A4 may significantly decrease velpatasvir plasma concentrations, leading to potentially reduced therapeutic effect.

            • sonidegib

              efavirenz will decrease the level or effect of sonidegib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sonidegib with strong or moderate CYP3A4 inducers.

            • sorafenib

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

              efavirenz and sorafenib both increase QTc interval. Avoid or Use Alternate Drug.

            • sotalol

              efavirenz and sotalol both increase QTc interval. Avoid or Use Alternate Drug.

            • sotorasib

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

            • St John's Wort

              St John's Wort will decrease the level or effect of efavirenz by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • stiripentol

              efavirenz will decrease the level or effect of stiripentol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration of stiripentol with strong CYP3A4 inducers, increase stiripentol dose.

            • sunitinib

              efavirenz and sunitinib both increase QTc interval. Avoid or Use Alternate Drug.

            • suvorexant

              efavirenz will decrease the level or effect of suvorexant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Strong CYP3A4 inducers may decrease suvorexant efficacy; if increased suvorexant dose required, do not exceed 20 mg/day

            • tacrolimus

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

            • tazemetostat

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

            • tepotinib

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

            • tetrabenazine

              efavirenz and tetrabenazine both increase QTc interval. Avoid or Use Alternate Drug.

            • tezacaftor

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

            • thiothixene

              efavirenz and thiothixene both increase QTc interval. Contraindicated.

            • tivozanib

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

            • tolvaptan

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

            • toremifene

              efavirenz and toremifene both increase QTc interval. Avoid or Use Alternate Drug.

            • trabectedin

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

            • trazodone

              efavirenz and trazodone both increase QTc interval. Avoid or Use Alternate Drug.

            • triazolam

              efavirenz increases levels of triazolam by decreasing metabolism. Contraindicated.

            • tucatinib

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

              efavirenz 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 efavirenz 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.

            • ubrogepant

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

            • ulipristal

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

            • upadacitinib

              efavirenz will decrease the level or effect of upadacitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid upadacitinib coadministration with strong CYP3A4 inducers.

            • vandetanib

              efavirenz decreases levels of vandetanib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with potent CYP3A4 inducers; these drugs reduce exposure to vandetanib by up to 40%.

              efavirenz and vandetanib both increase QTc interval. Avoid or Use Alternate Drug.

            • velpatasvir

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

            • vemurafenib

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

              efavirenz and vemurafenib both increase QTc interval. Avoid or Use Alternate Drug.

            • venetoclax

              efavirenz will decrease the level or effect of venetoclax by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of venetoclax with strong or moderate CYP3A inducers. Consider alternative treatment with agents that have less CYP3A induction.

            • voclosporin

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

              efavirenz and voclosporin both increase QTc interval. Avoid or Use Alternate Drug.

            • voriconazole

              efavirenz and voriconazole both increase QTc interval. Avoid or Use Alternate Drug.

            • voxelotor

              efavirenz will decrease 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 moderate or strong CYP3A4 inducers. If unable to avoid coadministration, increase voxelotor dose (see Dosage Modifications).

              voxelotor will increase the level or effect of efavirenz 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.

            • voxilaprevir

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

            • warfarin

              efavirenz will increase the level or effect of warfarin by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug.

            • zanubrutinib

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

            • ziprasidone

              efavirenz and ziprasidone both increase QTc interval. Avoid or Use Alternate Drug.

            Monitor Closely (322)

            • abacavir

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

            • abiraterone

              efavirenz decreases levels of abiraterone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Avoid coadministration of abiraterone with strong CYP3A4 inducers; if a strong CYP3A4 inducer must be used, increase abiraterone dosage frequency from once daily to twice daily.

            • acalabrutinib

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

            • albuterol

              efavirenz and albuterol both increase QTc interval. Use Caution/Monitor.

            • alfentanil

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

            • alfuzosin

              efavirenz and alfuzosin both increase QTc interval. Use Caution/Monitor.

            • almotriptan

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

            • alosetron

              efavirenz will increase the level or effect of alosetron by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

            • alprazolam

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

            • amitriptyline

              efavirenz will increase the level or effect of amitriptyline by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor.

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

              efavirenz and amitriptyline both increase QTc interval. Use Caution/Monitor.

            • amlodipine

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

            • apixaban

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

            • apomorphine

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

              efavirenz and apomorphine both increase QTc interval. Use Caution/Monitor.

            • aprepitant

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

            • arformoterol

              efavirenz and arformoterol both increase QTc interval. Use Caution/Monitor.

            • aripiprazole

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

              efavirenz and aripiprazole both increase QTc interval. Use Caution/Monitor.

            • arsenic trioxide

              efavirenz and arsenic trioxide both increase QTc interval. Use Caution/Monitor.

            • atazanavir

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

            • atogepant

              efavirenz will decrease the level or effect of atogepant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Recommended atogepant dosage with concomitant use of strong or moderate CYP3A4 inducers is 30 mg or 60 mg qDay.

            • atomoxetine

              efavirenz and atomoxetine both increase QTc interval. Use Caution/Monitor.

            • atorvastatin

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

            • avanafil

              efavirenz will decrease the level or effect of avanafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inhibitors may reduce avanafil clearance increasing systemic exposure to avanafil; increased levels may result in increased associated adverse events; the maximum recommended dose of STENDRA is 50 mg, not to exceed once every 24 hours for patients taking concomitant moderate CYP3A4 inhibitors

            • avapritinib

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

            • bazedoxifene/conjugated estrogens

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

            • belumosudil

              efavirenz will increase the level or effect of belumosudil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Increase belumosudil dosage to 200 mg PO BID when coadministered with strong CYP3A inducers.

            • belzutifan

              belzutifan will decrease the level or effect of efavirenz by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. If unable to avoid coadministration of belzutifan with sensitive CYP3A4 substrates, consider increasing the sensitive CYP3A4 substrate dose in accordance with its prescribing information.

            • benzhydrocodone/acetaminophen

              efavirenz will decrease the level or effect of benzhydrocodone/acetaminophen by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Caution when discontinuing CYP3A4 inducers that are coadministered with benzhydrocodone (prodrug of hydrocodone); plasma concentrations of hydrocodone may increase and can result in potentially fatal respiratory depression.

            • bortezomib

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

            • bosentan

              efavirenz will increase the level or effect of bosentan by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

            • brentuximab vedotin

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

            • brexanolone

              brexanolone, efavirenz. Either increases toxicity of the other by sedation. Use Caution/Monitor.

            • brexpiprazole

              efavirenz will decrease the level or effect of brexpiprazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Double brexpiprazole dose over 1-2 weeks if administered with a strong CYP3A4 inducer.

            • buprenorphine

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

            • buprenorphine buccal

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

            • buprenorphine subdermal implant

              efavirenz will decrease 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 inducer for signs and symptoms of withdrawal. If the dose of the concomitant CYP3A4 inducer 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 inducer is discontinued in a patient who has been stabilized on buprenorphine, monitor the patient for overmedication.

            • buprenorphine, long-acting injection

              efavirenz will decrease 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 inducers should be monitored to ensure buprenorphine plasma levels are adequate. If the buprenorphine dose is inadequate and the CYP3A4 inducer cannot be reduced or discontinued, transition the patient back to a buprenorphine formulation that permits dose adjustments.

            • bupropion

              efavirenz will decrease the level or effect of bupropion by increasing metabolism. Use Caution/Monitor. Coadministration with hepatic inducers reduced bupropion AUC and Cmax; hydroxybupropion (active metabolite) Cmax was increased

            • buspirone

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

            • cabazitaxel

              efavirenz will increase the level or effect of cabazitaxel by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Caution should be exercised with concomitant use of moderate CYP3A4 inhibitors.

            • calcifediol

              efavirenz, calcifediol. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Drugs that stimulate microsomal hydroxylation reduce the half-life of calcifediol.

            • calcitriol

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

            • cannabidiol

              efavirenz will increase the level or effect of cannabidiol by affecting hepatic enzyme CYP2C19 metabolism. Modify Therapy/Monitor Closely. Consider reducing the cannabidiol dose when coadministered with a moderate CYP2C19 inhibitor.

              efavirenz will decrease the level or effect of cannabidiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Consider an increase in cannabidiol dosage (based on clinical response and tolerability) when coadministered with a strong CYP3A4 inducer.

              cannabidiol, efavirenz. affecting hepatic enzyme CYP2B6 metabolism. Modify Therapy/Monitor Closely. Owing to the potential for both CYP2B6 induction and inhibition with the coadministration of CYP2B6 substrates and cannabidiol, consider reducing dosage adjustment of CYP2B6 substrates as clinically appropriate.

            • carbamazepine

              carbamazepine will decrease the level or effect of efavirenz by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor.

            • celecoxib

              efavirenz will increase the level or effect of celecoxib by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

            • cenobamate

              cenobamate will decrease the level or effect of efavirenz by affecting hepatic enzyme CYP2B6 metabolism. Modify Therapy/Monitor Closely. Increase dose of CYP2B6 substrate, as needed, when coadministered with cenobamate.

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

              cenobamate, efavirenz. Either increases levels of the other by sedation. Use Caution/Monitor.

            • chlordiazepoxide

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

            • chloroquine

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

            • chlorpheniramine

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

            • cilostazol

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

              efavirenz increases toxicity of cilostazol by affecting hepatic enzyme CYP2C19 metabolism. Modify Therapy/Monitor Closely. Consider decreasing cilostazol dose; moderate CYP2C19 inhibitors may increase serum levels of 3,4-dehydrocilostazol (active metabolite).

            • cinacalcet

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

            • ciprofloxacin

              efavirenz and ciprofloxacin both increase QTc interval. Use Caution/Monitor.

            • cisapride

              efavirenz and cisapride both increase QTc interval. Use Caution/Monitor.

            • clarithromycin

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

            • clobazam

              efavirenz will increase the level or effect of clobazam by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor. Dosage adjustment may be required; CYP2C19 inhibitors may result in increased exposure to N-desmethylclobazam (active metabolite).

              efavirenz, clobazam. Other (see comment). Use Caution/Monitor. Comment: Concomitant administration can increase the potential for CNS effects (e.g., increased sedation or respiratory depression).

            • clomipramine

              efavirenz and clomipramine both increase QTc interval. Use Caution/Monitor.

            • clonazepam

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

            • clopidogrel

              efavirenz decreases effects of clopidogrel by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Clopidogrel efficacy may be reduced by drugs that inhibit CYP3A4. Inhibition of platelet aggregation by clopidogrel is entirely due to an active metabolite. Clopidogrel is metabolized to this active metabolite in part by CYP3A4. .

            • clorazepate

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

            • clozapine

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

              efavirenz and clozapine both increase QTc interval. Use Caution/Monitor.

            • cobicistat

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

            • conivaptan

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

            • conjugated estrogens

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

            • conjugated estrogens, vaginal

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

            • cortisone

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

            • crizotinib

              efavirenz increases levels of crizotinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Caution should be exercised with concomitant use of moderate CYP3A inhibitors. .

            • crofelemer

              crofelemer increases levels of efavirenz 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

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

            • cyclosporine

              efavirenz will decrease the level or effect of cyclosporine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Closely monitor cyclosporine concentrations when starting, stopping, or adjusting dose of concurrent efavirez, especially within first 2 weeks.

            • dabrafenib

              dabrafenib will decrease the level or effect of efavirenz by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.

            • dantrolene

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

            • dapsone

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

            • daridorexant

              efavirenz and daridorexant both increase sedation. Modify Therapy/Monitor Closely. Coadministration increases risk of CNS depression, which can lead to additive impairment of psychomotor performance and cause daytime impairment.

            • darifenacin

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

            • darunavir

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

            • dasatinib

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

              efavirenz and dasatinib both increase QTc interval. Use Caution/Monitor.

            • deferasirox

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

            • degarelix

              efavirenz and degarelix both increase QTc interval. Use Caution/Monitor.

            • desipramine

              efavirenz and desipramine both increase QTc interval. Use Caution/Monitor.

            • deutetrabenazine

              efavirenz and deutetrabenazine both increase QTc interval. Use Caution/Monitor.

            • dexamethasone

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

            • diazepam

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

            • diazepam intranasal

              efavirenz will decrease the level or effect of diazepam intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Strong or moderate CYP3A4 inducers may increase rate of diazepam elimination; therefore, efficacy of diazepam may be decreased.

              efavirenz will increase the level or effect of diazepam intranasal by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor. Strong or moderate CYP2C19 inhibitors may decrease rate of diazepam elimination, thereby increasing adverse reactions to diazepam.

            • diclofenac

              efavirenz will increase the level or effect of diclofenac by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

            • didanosine

              didanosine, efavirenz. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Concomitant administration increases risk of liver toxicity.

            • difelikefalin

              difelikefalin and efavirenz both increase sedation. Use Caution/Monitor.

            • diltiazem

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

            • docetaxel

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

            • dolasetron

              efavirenz and dolasetron both increase QTc interval. Use Caution/Monitor.

            • donepezil

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

            • doxepin

              efavirenz and doxepin both increase QTc interval. Use Caution/Monitor.

            • doxorubicin

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

            • doxorubicin liposomal

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

            • dronabinol

              efavirenz 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 efavirenz by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. May decrease dronedarone levels.

            • elagolix

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

              elagolix will decrease the level or effect of efavirenz 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.

            • eliglustat

              efavirenz will decrease the level or effect of eliglustat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Strong CYP3A inducers significantly decreases eliglustat exposure; coadministration not recommended

              efavirenz and eliglustat both increase QTc interval. Use Caution/Monitor.

            • emtricitabine

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

            • encorafenib

              encorafenib, efavirenz. 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.

            • enfuvirtide

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

            • erlotinib

              efavirenz will decrease 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 efavirenz by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • erythromycin ethylsuccinate

              erythromycin ethylsuccinate will increase the level or effect of efavirenz by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • erythromycin lactobionate

              erythromycin lactobionate will increase the level or effect of efavirenz by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • erythromycin stearate

              erythromycin stearate will increase the level or effect of efavirenz by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • escitalopram

              efavirenz will increase the level or effect of escitalopram by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor.

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

              efavirenz and escitalopram both increase QTc interval. Use Caution/Monitor.

            • esketamine intranasal

              esketamine intranasal, efavirenz. Either increases toxicity of the other by sedation. Modify Therapy/Monitor Closely.

            • eslicarbazepine acetate

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

            • esomeprazole

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

            • estradiol

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

            • estradiol vaginal

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

            • estrogens conjugated synthetic

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

            • estrogens esterified

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

            • estropipate

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

            • eszopiclone

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

            • ethosuximide

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

            • etonogestrel

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

            • etoposide

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

            • etravirine

              efavirenz will increase the level or effect of etravirine by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor.

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

            • exemestane

              efavirenz will decrease the level or effect of exemestane by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. For patients receiving exemestane with a potent CYP3A4 inducer the recommended dose of exemestane is 50 mg daily after a meal.

            • fedratinib

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

            • felbamate

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

            • felodipine

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

            • fentanyl

              efavirenz will decrease the level or effect of fentanyl by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration of fentanyl with CYP3A4 inducers could lead to a decrease in fentanyl plasma concentrations, lack of efficacy or, possibly, development of a withdrawal syndrome in a patient who has developed physical dependence to fentanyl. After stopping a CYP3A4 inducer, as the effects of the inducer decline, the fentanyl plasma concentration will increase which could increase or prolong both the therapeutic and adverse effects.

            • fentanyl intranasal

              efavirenz will decrease the level or effect of fentanyl intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration of fentanyl with CYP3A4 inducers could lead to a decrease in fentanyl plasma concentrations, lack of efficacy or, possibly, development of a withdrawal syndrome in a patient who has developed physical dependence to fentanyl. After stopping a CYP3A4 inducer, as the effects of the inducer decline, the fentanyl plasma concentration will increase which could increase or prolong both the therapeutic and adverse effects.

            • fentanyl transdermal

              efavirenz will decrease the level or effect of fentanyl transdermal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration of fentanyl with CYP3A4 inducers could lead to a decrease in fentanyl plasma concentrations, lack of efficacy or, possibly, development of a withdrawal syndrome in a patient who has developed physical dependence to fentanyl. After stopping a CYP3A4 inducer, as the effects of the inducer decline, the fentanyl plasma concentration will increase which could increase or prolong both the therapeutic and adverse effects.

            • fentanyl transmucosal

              efavirenz will decrease the level or effect of fentanyl transmucosal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration of fentanyl with CYP3A4 inducers could lead to a decrease in fentanyl plasma concentrations, lack of efficacy or, possibly, development of a withdrawal syndrome in a patient who has developed physical dependence to fentanyl. After stopping a CYP3A4 inducer, as the effects of the inducer decline, the fentanyl plasma concentration will increase which could increase or prolong both the therapeutic and adverse effects.

            • fesoterodine

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

            • flibanserin

              efavirenz will decrease the level or effect of flibanserin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Strong CYP3A4 inducers substantially decrease flibanserin systemic exposure.

            • fluconazole

              efavirenz and fluconazole both increase QTc interval. Use Caution/Monitor.

            • fludrocortisone

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

            • fluoxetine

              efavirenz and fluoxetine both increase QTc interval. Use Caution/Monitor.

            • fluphenazine

              efavirenz and fluphenazine both increase QTc interval. Use Caution/Monitor.

            • flurazepam

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

            • flurbiprofen

              efavirenz will increase the level or effect of flurbiprofen by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

            • fluvastatin

              efavirenz will increase the level or effect of fluvastatin by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

            • fluvoxamine

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

              efavirenz and fluvoxamine both increase QTc interval. Use Caution/Monitor.

            • formoterol

              efavirenz and formoterol both increase QTc interval. Use Caution/Monitor.

            • fosamprenavir

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

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

            • fostemsavir

              efavirenz and fostemsavir both increase QTc interval. Use Caution/Monitor. QTc prolongation reported with higher than recommended doses of fostemsavir.

            • gefitinib

              efavirenz will decrease the level or effect of gefitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Increase gefitinib to 500 mg daily if coadministered with a strong CYP3A4 inducer. Resume gefitinib dose at 250 mg/day 7 days after discontinuing the strong inducer.

            • gemifloxacin

              efavirenz and gemifloxacin both increase QTc interval. Use Caution/Monitor.

            • gilteritinib

              efavirenz and gilteritinib both increase QTc interval. Use Caution/Monitor.

            • goserelin

              efavirenz and goserelin both increase QTc interval. Use Caution/Monitor.

            • granisetron

              efavirenz and granisetron both increase QTc interval. Use Caution/Monitor.

            • guanfacine

              efavirenz will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered.

            • haloperidol

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

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

            • histrelin

              efavirenz and histrelin both increase QTc interval. Use Caution/Monitor.

            • hydrocodone

              efavirenz will decrease the level or effect of hydrocodone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Caution when discontinuing CYP3A4 inducers that are coadministered with hydrocodone; plasma concentrations of hydrocodone may increase and can result in potentially fatal respiratory depression

            • hydrocortisone

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

            • hydroxyprogesterone caproate

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

            • hydroxyzine

              efavirenz and hydroxyzine both increase QTc interval. Use Caution/Monitor.

            • ibuprofen

              efavirenz will increase the level or effect of ibuprofen by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

            • ibuprofen IV

              efavirenz will increase the level or effect of ibuprofen IV by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

            • ifosfamide

              efavirenz increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

              efavirenz 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

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

              iloperidone increases levels of efavirenz 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.

            • imipramine

              efavirenz will increase the level or effect of imipramine by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor.

              efavirenz and imipramine both increase QTc interval. Use Caution/Monitor.

            • indacaterol, inhaled

              efavirenz and indacaterol, inhaled both increase QTc interval. Use Caution/Monitor.

            • indinavir

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

            • isoniazid

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

            • isosorbide dinitrate

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

            • isosorbide mononitrate

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

            • isradipine

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

              efavirenz and isradipine both increase QTc interval. Use Caution/Monitor.

            • istradefylline

              istradefylline will increase the level or effect of efavirenz 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.

            • ivacaftor

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

            • ivosidenib

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

            • ixabepilone

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

            • ketamine

              efavirenz will increase the level or effect of ketamine by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

              efavirenz 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 efavirenz by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • lamivudine

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

            • lansoprazole

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

            • lapatinib

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

              efavirenz and lapatinib both increase QTc interval. Use Caution/Monitor.

            • lasmiditan

              lasmiditan, efavirenz. Either increases effects of the other by sedation. Use Caution/Monitor. Coadministration of lasmiditan and other CNS depressant drugs, including alcohol have not been evaluated in clinical studies. Lasmiditan may cause sedation, as well as other cognitive and/or neuropsychiatric adverse reactions.

            • lemborexant

              lemborexant will decrease the level or effect of efavirenz by affecting hepatic enzyme CYP2B6 metabolism. Modify Therapy/Monitor Closely. Monitor CYP2B6 substrate for adequate clinical response. Consider increasing the CYP2B6 substrate dose according to specific prescribing recommendations.

            • letermovir

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

            • leuprolide

              efavirenz and leuprolide both increase QTc interval. Use Caution/Monitor.

            • levalbuterol

              efavirenz and levalbuterol both increase QTc interval. Use Caution/Monitor.

            • levamlodipine

              efavirenz will decrease the level or effect of levamlodipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. No information is available on the quantitative effects of CYP3A4 inducers on amlodipine. Closely monitor blood pressure when amlodipine is coadministered with CYP3A4 inducers.

            • levofloxacin

              efavirenz and levofloxacin both increase QTc interval. Use Caution/Monitor.

            • levonorgestrel intrauterine

              efavirenz decreases levels of levonorgestrel intrauterine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • levonorgestrel oral

              efavirenz decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • levonorgestrel oral/ethinylestradiol/ferrous bisglycinate

              efavirenz will decrease the level or effect of levonorgestrel oral/ethinylestradiol/ferrous bisglycinate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. The efficacy of hormonal contraceptives may be reduced. Use an alternative method of contraception or a backup method when enzyme inducers are used with combined hormonal contraceptives (CHCs), and continue backup contraception for 28 days after discontinuing enzyme inducer to ensure contraceptive reliability.

            • linagliptin

              efavirenz will decrease the level or effect of linagliptin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of alternative treatments is strongly recommended when linagliptin is to be administered with a CYP3A4 inducer.

              efavirenz will decrease the level or effect of linagliptin by Other (see comment). Use Caution/Monitor. Reports of hyperglycemia due to insulin resistance with protease inhibitors.

            • lithium

              efavirenz and lithium both increase QTc interval. Use Caution/Monitor.

            • loperamide

              efavirenz and loperamide both increase QTc interval. Use Caution/Monitor.

            • lopinavir

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

            • loratadine

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

            • losartan

              efavirenz will increase the level or effect of losartan by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor. May inhibit the conversion of losartan to its active metabolite E-3174. Importance of interaction not established; monitor individual therapeutic response to determine losartan dosage.

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

            • lumacaftor/ivacaftor

              lumacaftor/ivacaftor, efavirenz. affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. In vitro studies suggest that lumacaftor may induce and ivacaftor may inhibit CYP2B6 substrates. .

            • lurasidone

              efavirenz decreases levels of lurasidone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. It may be necessary to increase the lurasidone dose after chronic treatment (ie, 7 days or more) with moderate CYP3A inducers.

              lurasidone, efavirenz. Either increases toxicity of the other by Other (see comment). Use Caution/Monitor. Comment: Potential for increased CNS depressant effects when used concurrently; monitor for increased adverse effects and toxicity.

            • maprotiline

              efavirenz and maprotiline both increase QTc interval. Use Caution/Monitor.

            • maraviroc

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

            • marijuana

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

            • medroxyprogesterone

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

            • mefloquine

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

              efavirenz and mefloquine both increase QTc interval. Use Caution/Monitor.

            • meloxicam

              efavirenz will increase the level or effect of meloxicam by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

            • meperidine

              efavirenz will decrease the level or effect of meperidine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Increased toxic metabolite formation.

            • mestranol

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

            • metaxalone

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

            • methadone

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

            • methylprednisolone

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

            • midazolam

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

            • midazolam intranasal

              midazolam intranasal, efavirenz. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Concomitant use of barbiturates, alcohol, or other CNS depressants may increase risk of hypoventilation, airway obstruction, desaturation, or apnea and may contribute to profound and/or prolonged drug effect.

            • mifepristone

              efavirenz, mifepristone. Other (see comment). Use Caution/Monitor. Comment: Efavirenz shown in vitro to induce CYP3A4 and CYP2B6, but in vitro has been shown to inhibit CYP3A4 and therefore may affect mifepristone levels/effect; mifepristone inhibits CYP2B6, therefore increasing exposure of efavirenz.

            • mirtazapine

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

              efavirenz and mirtazapine both increase QTc interval. Use Caution/Monitor.

            • mitotane

              mitotane decreases levels of efavirenz 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

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

            • nafcillin

              nafcillin will decrease the level or effect of efavirenz by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Strong CYP3A4 inducers may increase metabolism of CYP3A4 substrates

            • naldemedine

              efavirenz will decrease the level or effect of naldemedine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Simulation using physiologically-based pharmacokinetic modeling suggests that concomitant use of moderated CYP3A4 inducers decrease exposure to naldemedine. The clinical consequence of this decreased exposure is unknown.

            • nefazodone

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

            • nelfinavir

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

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

            • nicardipine

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

            • nifedipine

              efavirenz will decrease the level or effect of nifedipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.

            • nilotinib

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

            • nortriptyline

              efavirenz and nortriptyline both increase QTc interval. Use Caution/Monitor.

            • octreotide

              efavirenz and octreotide both increase QTc interval. Use Caution/Monitor.

            • ofloxacin

              efavirenz and ofloxacin both increase QTc interval. Use Caution/Monitor.

            • olanzapine

              efavirenz and olanzapine both increase QTc interval. Use Caution/Monitor. Limited data, including some case reports, suggest that olanzapine may be associated with a significant prolongation of the QTc interval in rare instances

            • oliceridine

              efavirenz will decrease the level or effect of oliceridine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. If coadministration with a CYP3A4 inducer is necessary, consider increasing oliceridine dose until stable drug effects are achieved; monitor for signs of opioid withdrawal. If inducer is discontinued, consider oliceridine dosage reduction and monitor for signs of respiratory depression.

            • olodaterol inhaled

              efavirenz and olodaterol inhaled both increase QTc interval. Use Caution/Monitor.

            • omeprazole

              efavirenz will increase the level or effect of omeprazole by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor.

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

            • ondansetron

              efavirenz will decrease 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 efavirenz 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

              efavirenz will decrease the level or effect of osilodrostat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Monitor cortisol concentration and patient?s signs and symptoms during coadministration or discontinuation with strong CYP3A4 inducers. Adjust dose of osilodrostat if necessary.

              osilodrostat and efavirenz both increase QTc interval. Use Caution/Monitor.

            • ospemifene

              efavirenz decreases levels of ospemifene by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • oxaliplatin

              oxaliplatin will increase the level or effect of efavirenz by Other (see comment). Use Caution/Monitor. Monitor for ECG changes if therapy is initiated in patients with drugs known to prolong QT interval.

            • oxcarbazepine

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

            • oxycodone

              efavirenz decreases levels of oxycodone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • palbociclib

              efavirenz will decrease the level or effect of palbociclib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.

            • paricalcitol

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

            • pasireotide

              efavirenz and pasireotide both increase QTc interval. Use Caution/Monitor.

            • pazopanib

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

            • perphenazine

              efavirenz and perphenazine both increase QTc interval. Use Caution/Monitor.

            • phenytoin

              efavirenz will increase the level or effect of phenytoin by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

              phenytoin will decrease the level or effect of efavirenz by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. When given together, periodic monitoring for reduced efavirenz efficacy and phenytoin plasma concentrations are recommended .

              phenytoin will increase the level or effect of efavirenz by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

            • pimavanserin

              efavirenz will decrease the level or effect of pimavanserin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Avoid coadministration if possible. Monitor for reduced pimavanserin efficacy. An increase in pimavanserin dosage may be needed.

            • pimozide

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

            • piroxicam

              efavirenz will increase the level or effect of piroxicam by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

            • pitolisant

              efavirenz will decrease the level or effect of pitolisant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Pitolisant exposure is decreased by 50% if coadministered with strong CYP3A4 inducers. For patients stable on pitolisant 8.9 mg/day or 17.8 mg/day, double the pitolisant dose (ie, 17.8 mg or 35.6 mg, respectively) over 7 days. If the strong CYP3A4 inducer is discontinued, reduce pitolisant dosage by half.

            • polatuzumab vedotin

              efavirenz will decrease 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 inducer may decrease unconjugated MMAE AUC.

            • prednisolone

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

            • prednisone

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

            • primaquine

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

              efavirenz and primaquine both increase QTc interval. Use Caution/Monitor.

            • prochlorperazine

              efavirenz and prochlorperazine both decrease QTc interval. Use Caution/Monitor.

            • progesterone intravaginal gel

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

            • progesterone micronized

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

            • progesterone, natural

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

            • proguanil

              efavirenz decreases levels of proguanil by unspecified interaction mechanism. Use Caution/Monitor. May decrease serum concentrations of the active metabolite of proguanil.

            • promethazine

              efavirenz and promethazine both decrease QTc interval. Use Caution/Monitor.

            • protriptyline

              efavirenz and protriptyline both increase QTc interval. Use Caution/Monitor.

            • quazepam

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

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

            • quetiapine

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

            • quinidine

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

            • ramelteon

              efavirenz will increase the level or effect of ramelteon by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

            • repaglinide

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

            • ribociclib

              efavirenz will decrease the level or effect of ribociclib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of ribociclib with strong CYP3A inducers should be avoided.

            • rifabutin

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

            • rifampin

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

              rifampin will decrease the level or effect of efavirenz by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor.

            • riociguat

              efavirenz will decrease the level or effect of riociguat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Data not available for dose adjustment

            • risperidone

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

            • ritonavir

              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.

            • rivaroxaban

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

            • roflumilast

              efavirenz will decrease the level or effect of roflumilast by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration not recommended; strong cytochrome P450 enzyme inducers decrease systemic exposure to roflumilast and may reduce the therapeutic effectiveness

            • romidepsin

              efavirenz will decrease the level or effect of romidepsin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration with strong 3A4 inducers should be avoided if possible.

              efavirenz and romidepsin both increase QTc interval. Use Caution/Monitor.

            • rucaparib

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

            • ruxolitinib

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

            • ruxolitinib topical

              efavirenz will increase the level or effect of ruxolitinib topical by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • salmeterol

              efavirenz and salmeterol both increase QTc interval. Use Caution/Monitor.

            • saquinavir

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

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

            • selexipag

              efavirenz will increase the level or effect of selexipag by decreasing metabolism. Modify Therapy/Monitor Closely. Reduce selexipag dose to once daily if coadministered with moderate CYP2C8 inhibitors.

            • sertraline

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

              efavirenz and sertraline both increase QTc interval. Use Caution/Monitor.

            • sildenafil

              efavirenz will decrease the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potent CYP3A4 inducers are expected to cause substantial decreases in sildenafil plasma levels

            • simvastatin

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

            • solifenacin

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

              efavirenz and solifenacin both increase QTc interval. Use Caution/Monitor.

            • sorafenib

              efavirenz decreases levels of sorafenib by increasing metabolism. Use Caution/Monitor.

            • stavudine

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

            • stiripentol

              stiripentol, efavirenz. affecting hepatic enzyme CYP2B6 metabolism. Modify Therapy/Monitor Closely. Stiripentol is a CYP2B6 inhibitor and inducer. Monitor CYP2B6 substrates coadministered with stiripentol for increased or decreased effects. CYP2B6 substrates may require dosage adjustment.

              stiripentol, efavirenz. 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, efavirenz. Either increases effects of the other by sedation. Use Caution/Monitor. Concomitant use stiripentol with other CNS depressants, including alcohol, may increase the risk of sedation and somnolence.

            • sufentanil SL

              efavirenz decreases effects of sufentanil SL by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration of CYP3A4 inducers may decrease sufentanil levels and efficacy, possibly precipitating withdrawal syndrome in patients who have developed physical dependence to sufentanil. Discontinuation of concomitantly used CYP3A4 inducers may increase sufentanil plasma concentration.

            • sulfamethoxazole

              efavirenz will increase the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

            • sunitinib

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

            • tacrolimus

              efavirenz and tacrolimus both increase QTc interval. Use Caution/Monitor.

            • tadalafil

              efavirenz will decrease the level or effect of tadalafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Avoid combination in pulmonary HTN patients. For patients with ED, monitor response to tadalafil carefully because of potential for decreased effectiveness.

            • tamoxifen

              efavirenz, tamoxifen. affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor. CYP2C9/10 inhibition decreases tamoxifen metabolism to active metabolites.

              efavirenz, tamoxifen. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inhibition decreases metabolism of tamoxifen to N-desmethyl tamoxifen (active metabolite with similar biologic activity).

            • tamsulosin

              efavirenz increases levels of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Dose reduction may be needed for coadministered drugs that are predominantly metabolized by CYP3A.

            • tasimelteon

              efavirenz will decrease the level or effect of tasimelteon by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Avoid coadministration of tasimelteon with strong CYP3A4 inducers

            • tazemetostat

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

            • tecovirimat

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

            • telavancin

              efavirenz and telavancin both increase QTc interval. Use Caution/Monitor.

            • telotristat ethyl

              telotristat ethyl will decrease the level or effect of efavirenz by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Consider increasing dosage of interacting drug, if necessary

            • temsirolimus

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

            • teniposide

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

            • tenofovir DF

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

            • terbinafine

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

            • tetracycline

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

            • theophylline

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

            • tiagabine

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

            • ticagrelor

              efavirenz decreases levels of ticagrelor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Avoid use of ticagrelor with potent CYP3A inducers.

            • ticlopidine

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

              ticlopidine will decrease the level or effect of efavirenz by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor.

            • tinidazole

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

            • tipranavir

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

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

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

            • tofacitinib

              efavirenz increases levels of tofacitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Loss of, or decreased response to tofacitinib may occur when coadministered with potent CYP3A4 inducers.

            • tolbutamide

              efavirenz will increase the level or effect of tolbutamide by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

            • tolterodine

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

            • toremifene

              efavirenz decreases levels of toremifene by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers increase rate of toremifene metabolism, lowering the steady-state concentration in serum.

            • tramadol

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

            • trazodone

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

            • triamcinolone acetonide injectable suspension

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

            • triazolam

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

            • triclabendazole

              efavirenz and triclabendazole both increase QTc interval. Use Caution/Monitor.

            • trifluoperazine

              efavirenz and trifluoperazine both decrease QTc interval. Use Caution/Monitor.

            • trimipramine

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

              efavirenz will decrease the level or effect of trimipramine by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor.

              efavirenz and trimipramine both increase QTc interval. Use Caution/Monitor.

            • triptorelin

              efavirenz and triptorelin both increase QTc interval. Use Caution/Monitor.

            • umeclidinium bromide/vilanterol inhaled

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

              efavirenz and umeclidinium bromide/vilanterol inhaled both decrease QTc interval. Use Caution/Monitor.

            • vardenafil

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

              efavirenz and vardenafil both increase QTc interval. Use Caution/Monitor.

            • venlafaxine

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

              efavirenz and venlafaxine both decrease QTc interval. Use Caution/Monitor.

            • verapamil

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

            • vilanterol/fluticasone furoate inhaled

              efavirenz will decrease the level or effect of vilanterol/fluticasone furoate inhaled by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Avoid or Use Alternate Drug.

              efavirenz and vilanterol/fluticasone furoate inhaled both increase QTc interval. Use Caution/Monitor.

            • vilazodone

              efavirenz decreases levels of vilazodone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Consider increasing vilazodone dose up to 2-fold (not to exceed 80 mg/day) when coadministered with strong CYP3A4 inducers for >14 days.

            • vorapaxar

              efavirenz decreases levels of vorapaxar by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • vorinostat

              efavirenz and vorinostat both increase QTc interval. Use Caution/Monitor.

            • vortioxetine

              efavirenz decreases levels of vortioxetine by increasing metabolism. Modify Therapy/Monitor Closely. Consider increasing the vortioxetine dose when coadministered with strong CYP inducers for >14 days; not to exceed 3 times original vortioxetine dose.

            • warfarin

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

            • zidovudine

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

            • zonisamide

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

            Minor (95)

            • alosetron

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

            • ambrisentan

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

            • amobarbital

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

            • aprepitant

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

            • armodafinil

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

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

            • artemether/lumefantrine

              artemether/lumefantrine will decrease the level or effect of efavirenz by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • atazanavir

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

              efavirenz decreases levels of atazanavir by unspecified interaction mechanism. Minor/Significance Unknown. May be coadministered; see atazanavir monograph for dosing info.

            • bosentan

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

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

            • butabarbital

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

            • butalbital

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

            • caspofungin

              efavirenz decreases levels of caspofungin by increasing metabolism. Minor/Significance Unknown.

            • cevimeline

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

            • cimetidine

              efavirenz will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

            • clarithromycin

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

            • clomipramine

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

            • cocaine

              efavirenz will increase the level or effect of cocaine by affecting hepatic enzyme CYP2B6 metabolism. Minor/Significance Unknown.

            • colchicine

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

            • conivaptan

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

            • cortisone

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

            • cyclosporine

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

            • darifenacin

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

            • darunavir

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

            • dasatinib

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

            • desipramine

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

            • dexamethasone

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

            • DHEA, herbal

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

            • diazepam

              efavirenz will increase the level or effect of diazepam by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

            • disopyramide

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

            • dutasteride

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

            • eplerenone

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

            • esomeprazole

              efavirenz will increase the level or effect of esomeprazole by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

            • etravirine

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

            • eucalyptus

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

            • finasteride

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

            • fluconazole

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

            • fludrocortisone

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

            • fosamprenavir

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

            • fosphenytoin

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

            • galantamine

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

            • grapefruit

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

            • griseofulvin

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

            • hydrocortisone

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

            • imatinib

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

            • imipramine

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

            • indinavir

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

            • ketoconazole

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

            • lansoprazole

              efavirenz will increase the level or effect of lansoprazole by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

            • lapatinib

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

            • losartan

              efavirenz decreases effects of losartan by decreasing metabolism. Minor/Significance Unknown. May inhibit the conversion of losartan to its active metabolite E-3174. Importance of interaction not established; monitor individual therapeutic response to determine losartan dosage.

            • lumefantrine

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

            • marijuana

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

            • methylprednisolone

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

            • metronidazole

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

            • miconazole vaginal

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

            • modafinil

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

            • montelukast

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

            • nelfinavir

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

            • nifedipine

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

            • nilotinib

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

            • nimodipine

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

            • nitrendipine

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

            • oxybutynin

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

            • paclitaxel

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

            • paclitaxel protein bound

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

            • pantoprazole

              efavirenz will increase the level or effect of pantoprazole by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

            • parecoxib

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

            • pentobarbital

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

            • phenobarbital

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

            • pioglitazone

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

            • ponatinib

              efavirenz decreases levels of ponatinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown. Avoid unless the coadministration outweighs the possible risk of ponatinib underexposure; monitor for signs of reduced efficacy.

            • posaconazole

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

            • prednisone

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

            • primidone

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

            • propafenone

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

            • quinine

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

            • quinupristin/dalfopristin

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

            • rabeprazole

              efavirenz will increase the level or effect of rabeprazole by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

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

            • ramelteon

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

            • rifapentine

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

            • ritonavir

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

            • rufinamide

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

            • saxagliptin

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

            • secobarbital

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

            • sufentanil

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

            • topiramate

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

            • verapamil

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

            • vinblastine

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

            • vincristine

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

            • vincristine liposomal

              efavirenz will decrease the level or effect of vincristine liposomal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

            • vinorelbine

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

            • warfarin

              efavirenz will increase the level or effect of warfarin by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

            • zafirlukast

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

            • zaleplon

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

            • ziprasidone

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

            • zolpidem

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

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            Adverse Effects

            >10%

            Total cholesterol increased (20-40%)

            Diarrhea (3-14%, children up to 39%)

            HDL increased (25-35%)

            Dizziness (28.1%)

            Rash (5-26%)

            Fever (children 21%)

            Depression (19%)

            Insomnia (16.3%)

            Cough (children 16%)

            Vomiting (3-12%)

            Anxiety (2-13%)

            Nausea (2-12%)

            1-10%

            Neutropenia (2-10%)

            Pruitis (9%)

            Impaired concentration (8.3%)

            Transaminases increased (2-8%)

            Somnolence (7.0%)

            Abnormal dreams (6.2%)

            Amylase increased (6%)

            Hyperglycemia (2-5%)

            Dyspepsia (4%)

            Abdominal pain (2-3%)

            Anorexia (2%)

            Hallucinations (1.2%)

            Postmarketing Reports

            Serious psychiatric events: severe depression (2.4%), suicidal ideation (0.7%), nonfatal suicide attempts (0.5%), aggressive behavior (0.4%), paranoid reactions (0.4% ), manic reactions (0.2%)

            Central and Peripheral Nervous System: abnormal coordination, ataxia, encephalopathy, cerebellar coordination and balance disturbances, convulsions, hypoesthesia, paresthesia, neuropathy, tremor, vertigo

            Stevens-Johnson syndrome

            Erythema multiforme

            Exfoliative dermatitis

            Hepatotoxicity

            Pancreatitis

            Cardiac arrhythmias

            Prolonged sedation, or respiratory depression

            Vertigo

            Catatonia

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            Warnings

            Contraindications

            Previously demonstrated clinically significant hypersensitivity (eg, Stevens-Johnson syndrome, erythema multiforme, or toxic skin eruptions)

            Coadministration of efavirenz with elbasvir and grazoprevir

            Cautions

            Hepatic impairment; not recommended for patients with moderate or severe hepatic impairment because there are insufficient data to determine whether dose adjustment is necessary

            Monitor liver function tests before and during treatment in patients with underlying hepatic disease, including hepatitis B or C coinfection, marked transaminase elevations, or who are taking medications associated with liver toxicity; among reported cases of hepatic failure, a few occurred in patients with no pre-existing hepatic disease; weigh risk/benefit if AST/ALT >5 xULN; discontinue therapy if elevation of serum transaminases is accompanied by clinical signs or symptoms of hepatitis or hepatic decompensation

            Redistribution of fat may occur (cushingoid appearance)

            Risk of serious psychiatric events (eg, depression, suicidality, paranoia, manic episodes); immediate medical evaluation recommended for serious psychiatric symptoms such as severe depression or suicidal ideation; there have been occasional postmarketing reports of death by suicide, delusions, psychosis-like behavior and catatonia; a causal relationship to the use of efavirenz cannot be determined from these reports

            CNS symptoms reported (eg, dizziness, insomnia, impaired concentration, somnolence, abnormal dreams, and hallucinations); nervous system symptoms (NSS) are frequent and usually begin 1-2 days after initiating therapy and resolve in 2-4 weeks; dosing at bedtime may improve tolerability; NSS are not predictive of onset of psychiatric symptoms

            Risk of skin rash - discontinue if severe rash associated wtih blistering, desquamation, mucosal involvement, or fever

            Use caution in history of seizures

            Total cholesterol and triglyceride elevations may occur; monitor before therapy and periodically thereafter

            Women should avoid pregnancy; use 2 forms of contraception including a barrier method; postmarketing reports of contraceptive failure in patients on efavirenz while on an implantable hormonal contraceptive; avoid administration in first trimester of pregnancy as fetal harm may occur

            Risk of immune reconstitution syndrome if used in combination with other antiretroviral drugs; immune reconstitution syndrome may necessitate further evaluation and treatment

            Autoimmune disorders (eg, Graves’ disease, polymyositis, Guillain-Barré syndrome, autoimmune hepatitis) reported in the setting of immune reconstitution, however, the time to onset is more variable, and can occur many months after initiation of treatment

            Not for use as a single agent or add on as a sole agent to a failing regimen; consider potential for cross-resistance when choosing other agents

            Not recommended with ATRIPLA, which contains efavirenz, emtricitabine, and tenofovir disoproxil fumarate, unless needed for dose adjustment when coadministered with rifampin

            Postmarketing cases of catatonia reported, which may be associated with increased efavirenz exposure; patients with serious psychiatric adverse experiences should seek immediate medical evaluation to assess possibility that symptoms may be related to therapy, and if so, to determine whether risks of continued therapy outweigh the benefits

            Consider alternatives in patients taking other medications with known risk of Torsade de Pointes or in patients at higher risk of Torsade de Pointes

            Late-onset neurotoxicity

            • Ataxia and encephalopathy (impaired consciousness, confusion, psychomotor slowing, psychosis, delirium), may occur months to years after beginning therapy
            • Some events of late-onset neurotoxicity have occurred in patients with CYP2B6 genetic polymorphisms which are associated with increased drug levels despite standard dosing therapy
            • Evaluate promptly patients presenting with signs and symptoms of serious neurologic adverse experiences to assess the possibility that these events may be related to therapy, and whether discontinuation is warranted

            Interactions

            • Efavirenz plasma concentrations may be altered by substrates, inhibitors, or inducers of CYP3A
            • Likewise, efavirenz may alter plasma concentrations of drugs metabolized by CYP3A or CYP2B6
            • The most prominent effect of efavirenz at steady-state is induction of CYP3A and CYP2B6
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            Pregnancy & Lactation

            Pregnancy Category: D

            Lactation: Unknown if distributed in human milk; the CDC advises HIV-infected women not to breastfeed to avoid postnatal transmission of HIV

            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

            Non-nucleoside reverse transcriptase inhibitor (NNRTI) against HIV-1

            Absorption

            Peak Plasma Time: 2.5-4 hr

            Metabolism

            Metabolized by liver CYP3A4 and CYP2B6

            Inhibits: CYP2C9; CYP2C19, and CYP3A4 (in vitro)

            Induces: CYP3A4 (in vivo)

            Elimination

            Half-Life: 41 hr ± 20 hr

            Excretion: Urine (14-34%); feces (16-61%)

            Distribution

            Protein binding: 99% (albumin)

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            Administration

            Oral Administration

            Swallow capsule or table whole; do not break tablet

            Take only on empty stomach, preferably at bedtime

            Capsule sprinkle method

            • If unable to swallow capsule or tablet, capsule contents may be mixed with a small amount of food (ie ~2 teaspoonfuls) or room temperature formula (ie, 10 mL)
            • Consume food/formula mixture within 30 minutes of mixing
            • Do not consume additional food for at least 2 hr after administration
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            Images

            BRAND FORM. UNIT PRICE PILL IMAGE
            efavirenz oral
            -
            600 mg tablet
            efavirenz oral
            -
            200 mg capsule
            efavirenz oral
            -
            600 mg tablet
            Sustiva oral
            -
            50 mg capsule
            Sustiva oral
            -
            200 mg capsule
            Sustiva oral
            -
            600 mg tablet

            Copyright © 2010 First DataBank, Inc.

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            Patient Handout

            Patient Education
            efavirenz oral

            EFAVIRENZ - ORAL

            (eh-FAV-er-enz)

            COMMON BRAND NAME(S): Sustiva

            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. Efavirenz belongs to a class of drugs known as non-nucleoside reverse transcriptase inhibitors (NNRTIs).Efavirenz 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 if available from your pharmacist before you start taking efavirenz and each time you get a refill. If you have any questions regarding the information, consult your doctor or pharmacist.Take this medication by mouth on an empty stomach, without food, usually once daily at bedtime or as directed by your doctor. Taking efavirenz with food increases the blood level of this medication, which may increase your risk of certain side effects. See Side Effects section.Swallow this medication whole with water. If you have difficulty swallowing the capsule, it may be opened and the contents mixed gently in a small amount (1 to 2 teaspoons) of soft food such as applesauce, grape jelly, or yogurt. After taking the mixed medication, add 2 more teaspoons of food to the empty mixing container. Swallow the remaining mixture to make sure that you get the entire dose. Swallow within 30 minutes of mixing. Do not eat any food for 2 hours after taking this medication. For babies who cannot eat solid foods, the contents may be mixed in 2 teaspoons of infant formula and drawn up into an oral syringe to be given to the baby. (See Patient Information Leaflet.)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). In children, the dosage is also based on weight.It is very important to continue taking this medication (and other HIV medications) exactly as prescribed by your doctor. Do not skip any doses. Do not increase your dose, take this drug more often 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 (resistant), or worsen side effects.For the best effect, take this medication at evenly spaced times. To help you remember, take this medication at the same time every day.

            SIDE EFFECTS: Dizziness, trouble sleeping, drowsiness, unusual dreams, and trouble concentrating may frequently occur. These side effects may begin 1-2 days after starting this medication and usually go away in 2-4 weeks. They are also reduced by taking efavirenz on an empty stomach at bedtime. Avoid alcohol and street drugs while taking efavirenz. They may worsen these side effects.Tiredness, headache, nausea, vomiting, and diarrhea may also occur.If any of these effects persist or worsen, tell your doctor or pharmacist promptly.Remember that this medication has been prescribed because your doctor 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 unsteadiness, loss of coordination, trouble swallowing/speaking/chewing, trouble moving your eyes).Tell your doctor right away if any of these rare but serious side effects occur: signs of liver problems (such as persistent nausea/vomiting, stomach/abdominal pain, severe tiredness, yellowing eyes/skin, dark urine), mental/mood changes (such as depression, rare thoughts of suicide, nervousness, angry behavior, hallucinations, confusion), loss of coordination.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.Get medical help right away if you have any very serious side effects, including: fast/irregular heartbeat, severe dizziness, fainting.Efavirenz can commonly cause a rash that is usually not serious. In adults, a rash may occur in the first 2 weeks after starting treatment and if it is not serious, it will usually resolve in 4 weeks. In children, a rash may occur in the first 4 weeks after starting treatment. However, you may not be able to tell it apart from a rare rash that could be a sign of a severe reaction. Seek immediate medical attention if you develop any rash.A very serious allergic reaction to this drug is unlikely, but seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction may include: rash, blisters, peeling skin, fever, 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 efavirenz, 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: mental/mood conditions (such as depression, thoughts of suicide, psychosis), liver problems (such as hepatitis B or C, cirrhosis), drug/substance/alcohol abuse, seizures, high cholesterol/triglyceride levels.Efavirenz may cause a condition that affects the heart rhythm (QT prolongation). QT prolongation can rarely cause serious (rarely fatal) fast/irregular heartbeat and other symptoms (such as severe dizziness, fainting) that need medical attention right away.The risk of QT prolongation may be increased if you have certain medical conditions or are taking other drugs that may cause QT prolongation. Before using efavirenz, tell your doctor or pharmacist of all the drugs you take and if you have any of the following conditions: certain heart problems (heart failure, slow heartbeat, QT prolongation in the EKG), family history of certain heart problems (QT prolongation in the EKG, sudden cardiac death).Low levels of potassium or magnesium in the blood may also increase your risk of QT prolongation. This risk may increase if you use certain drugs (such as diuretics "water pills") or if you have conditions such as severe sweating, diarrhea, or vomiting. Talk to your doctor about using efavirenz safely.This drug may make you dizzy or drowsy or cause trouble concentrating. Alcohol or marijuana (cannabis) can worsen these effects. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Avoid alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).A rash may be more common and serious in children taking efavirenz. Report any rash right away. The doctor may prescribe an antihistamine for your child to take before efavirenz is started. Consult the doctor for more information.Older adults may be more sensitive to the side effects of this drug, especially QT prolongation (see above).During pregnancy, this medication should be used only when clearly needed. Treatment can lower the risk of passing HIV infection to your baby, and efavirenz may be part of that treatment. Women of childbearing age should ask about reliable forms of birth control while using this medication and for 12 weeks after stopping treatment. If you become pregnant, talk to your doctor right away about the risks and benefits of this medication.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.Some products that may interact with this drug include: a certain combination product used to treat chronic hepatitis C (ombitasvir/paritaprevir/ritonavir/dasabuvir), orlistat.Do not take this medication with other products that contain efavirenz unless specifically directed by your doctor.Other medications can affect the removal of efavirenz from your body, which may affect how efavirenz works. Examples include some drugs used to treat seizures (such as carbamazepine, phenobarbital, phenytoin), rifamycins (such as rifampin), among others.Efavirenz can speed up the removal of many other medications from your body, which may affect how they work. Examples of affected drugs include atovaquone/proguanil, azole antifungals (such as itraconazole, ketoconazole), bedaquiline, cobicistat, elbasvir/grazoprevir, macrolide antibiotics (such as clarithromycin), methadone, rifabutin, sertraline, some cholesterol-lowering statins (such as atorvastatin, pravastatin, simvastatin), certain protease inhibitors (boceprevir, simeprevir), warfarin, among others.Some other drugs to treat HIV infection (such as elvitegravir, other NNRTIs including etravirine/nevirapine/rilpivirine) may also interact with efavirenz. If you are taking atazanavir with this medication, you may need to also take another medication (ritonavir). Consult your doctor or pharmacist for more details.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. (See also Precautions section.)Tell your doctor or pharmacist if you are taking other products that cause drowsiness including alcohol, marijuana (cannabis), antihistamines (such as cetirizine, diphenhydramine), drugs for sleep or anxiety (such as diazepam, zolpidem), muscle relaxants, and opioid pain relievers (such as codeine).Check the labels on all your medicines (such as allergy or cough-and-cold products) because they may contain ingredients that cause drowsiness. Ask your pharmacist about using those products safely.This medication may interfere with certain laboratory tests (including urine cannabinoid tests), possibly causing false test results. Make sure laboratory personnel and all your doctors know you use this drug.

            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.Lab and/or medical tests (such as liver tests, viral load, T-cell counts, cholesterol and triglyceride levels) should be done before you start taking this medication and while you are taking it. Women of childbearing age should also have a pregnancy test before starting this medication. Keep all medical and lab appointments. Consult your doctor for more details.

            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 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 August 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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            Tier Description
            1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
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            Code Definition
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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.