tezacaftor/ivacaftor (Rx)

Cystic Fibrosis

Indicated for cystic fibrosis (CF) in patients who are homozygous for the F508del mutation or who have at least 1 mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene that is responsive to tezacaftor/ivacaftor based on in vitro data and/or clinical evidence

Morning dose: One tezacaftor/ivacaftor 100-mg/150-mg fixed-dose tablet PO

Evening dose: One ivacaftor 150-mg tablet PO

Administer morning and evening doses ~12 hr apart

Dosage Modifications

Hepatic impairment

• Mild (Child-Pugh A): No dose adjustment required

• Moderate (Child-Pugh B)

  • Morning dose: One tablet of tezacaftor 100 mg/ivacaftor 150 mg PO qDay
  • Evening dose: Omit evening ivacaftor 150-mg dose

• Severe (Child-Pugh C)

  • Morning dose: One tablet of tezacaftor 100 mg/ivacaftor 150 mg PO once daily or less frequently
  • Evening dose: Omit evening ivacaftor 150-mg dose

Renal impairment

• Mild or moderate: No dose adjustment required
• Severe or ESRD: Caution recommended
• Not studied in moderate/severe impairment or ESRD

Coadministration with CYP3A inhibitors

• Avoid food or drink containing grapefruit or Seville oranges during treatment

• Moderate CYP3A inhibitors

  • Morning dose: Alternate dosing schedule (ie, day 1, administer tezacaftor 100 mg/ivacaftor 150 mg qDay; on day 2, administer ivacaftor 150 mg qDay; continue dosing schedule with tezacaftor 100 mg/ivacaftor 150 mg or ivacaftor 150 mg on alternate days)
  • Evening dose: Do not administer

• Strong CYP3A inhibitors

  • Morning dose: Adjust dose to twice weekly, taken ~3-4 days apart (ie, on day 1, administer tezacaftor 100 mg/ivacaftor 150 mg qDay; do not administer any tablets on days 2 and 3; on day 4, administer tezacaftor 100 mg/ivacaftor 150 mg qDay; continue dosing with tezacaftor 100 mg/ivacaftor 150 mg twice a week, administered ~3 -4 days apart)
  • Evening dose: Do not administer

Dosing Considerations

If the patient’s genotype is unknown, an FDA-cleared CF mutation test should be used to detect the presence of a CFTR mutation, followed by verification with bidirectional sequencing when recommended by the mutation test instructions for use

Cystic Fibrosis

Indicated for cystic fibrosis in patients aged ≥6 yr who are homozygous for the F508del mutation or who have at least 1 mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene that is responsive to tezacaftor/ivacaftor based on in vitro data and/or clinical evidence

<6 years: Safety and efficacy not established

6 to <12 years weighing <30 kg

• Morning dose: One tezacaftor/ivacaftor 50-mg/75-mg fixed-dose tablet PO
• Evening dose: One ivacaftor 75-mg tablet PO
• Administer morning and evening doses ~12 hr apart

≥6 years weighing ≥30 kg

• Morning dose: One tezacaftor/ivacaftor 100-mg/150-mg fixed-dose tablet PO
• Evening dose: One ivacaftor 150-mg tablet PO
• Administer morning and evening doses ~12 hr apart

Dosage Modifications

Hepatic impairment for patients aged 6 to <12 years weighing <30 kg

• Mild (Child-Pugh A): No dose adjustment required

• Moderate (Child-Pugh B)

  • Morning dose: One tablet of tezacaftor 50 mg/ivacaftor 75 mg PO qDay
  • Evening dose: Omit evening ivacaftor 75-mg dose

• Severe (Child-Pugh C)

  • Morning dose: One tablet of tezacaftor 50 mg/ivacaftor 75 mg PO qDay or less frequently
  • Evening dose: Omit evening ivacaftor 75-mg dose

Hepatic impairment patients aged ≥6 years weighing ≥30 kg

• Mild (Child-Pugh A): No dose adjustment required

• Moderate (Child-Pugh B)

  • Morning dose: One tablet of tezacaftor 100 mg/ivacaftor 150 mg PO qDay
  • Evening dose: Omit evening ivacaftor 150-mg dose

• Severe (Child-Pugh C)

  • Morning dose: One tablet of tezacaftor 100 mg/ivacaftor 150 mg PO qDay or less frequently
  • Evening dose: Omit evening ivacaftor 150-mg dose

Renal impairment

• Mild or moderate: No dose adjustment required
• Severe or ESRD: Not studied, caution recommended
• Not studied in moderate/severe impairment or ESRD

Coadministration with CYP3A inhibitors for patients aged 6 to <12 years weighing <30 kg

• Avoid food or drink containing grapefruit or Seville oranges during treatment

• Moderate CYP3A inhibitors

  • Morning dose: Alternate dosing schedule (ie, day 1, administer tezacaftor 50 mg/ivacaftor 75 mg qDay; on day 2, administer ivacaftor 75 mg qDay; continue dosing schedule with tezacaftor 50 mg/ivacaftor 75 mg or ivacaftor 75 mg on alternate days)
  • Evening dose: Do not administer

• Strong CYP3A inhibitors

  • Morning dose: Adjust dose to twice weekly, taken ~3-4 days apart (ie, on day 1, administer tezacaftor 50 mg/ivacaftor 75 mg qDay; do not administer any tablets on days 2 and 3; on day 4, administer tezacaftor 50 mg/ivacaftor 75 mg qDay; continue dosing with tezacaftor 50 mg/ivacaftor 75 mg twice a week, administered ~3 -4 days apart)
  • Evening dose: Do not administer

Coadministration with CYP3A inhibitors for patients aged ≥6 years weighing ≥30 kg

• Avoid food or drink containing grapefruit or Seville oranges during treatment

• Moderate CYP3A inhibitors

  • Morning dose: Alternate dosing schedule (ie, day 1, administer tezacaftor 100 mg/ivacaftor 150 mg qDay; on day 2, administer ivacaftor 150 mg qDay; continue dosing schedule with tezacaftor 100 mg/ivacaftor 150 mg or ivacaftor 150 mg on alternate days)
  • Evening dose: Do not administer

• Strong CYP3A inhibitors

  • Morning dose: Adjust dose to twice weekly, taken ~3-4 days apart (ie, on day 1, administer tezacaftor 100 mg/ivacaftor 150 mg qDay; do not administer any tablets on days 2 and 3; on day 4, administer tezacaftor 100 mg/ivacaftor 150 mg qDay; continue dosing with tezacaftor 100 mg/ivacaftor 150 mg twice a week, administered ~3 -4 days apart)
  • Evening dose: Do not administer

Dosing Considerations

If the patient’s genotype is unknown, an FDA-cleared cystic fibrosis mutation test should be used to detect the presence of a CFTR mutation, followed by verification with bidirectional sequencing when recommended by the mutation test instructions for use

Contraindicated (1)

• lonafarnib

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

Serious - Use Alternative (62)

• abametapir

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

• amobarbital

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

• apalutamide

  apalutamide will decrease the level or effect of ivacaftor 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.

• apalutamide

  apalutamide will decrease the level or effect of tezacaftor 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.

• avapritinib

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

• bosentan

  bosentan will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  bosentan decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).

• butabarbital

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

• carbamazepine

  carbamazepine decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).

• butalbital

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

• carbamazepine

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

• chloramphenicol

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

• cimetidine

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

• colchicine

  ivacaftor increases levels of colchicine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. Avoid use of colchicine with P-gp inhibitors. If coadministration is necessary, decrease colchicine dose or frequency as recommended in prescribing information. Use of any colchicine product in conjunction with P-gp inhibitors is contraindicated in patients with renal or hepatic impairment. .

• dabigatran

  ivacaftor increases levels of dabigatran by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. Atrial fibrillation: Avoid coadministering dabigatran with P-gp inhibitors if CrCl <30 mL/min. DVT/PE treatment: Avoid coadministering dabigatran with P-gp inhibitors if CrCl <50 mL/min.

• dabrafenib

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

• dexamethasone

  dexamethasone will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  dexamethasone decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).

• efavirenz

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

• elacestrant

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

• enzalutamide

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

• enzalutamide

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

• eslicarbazepine acetate

  eslicarbazepine acetate will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  eslicarbazepine acetate will decrease the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold)

• etravirine

  etravirine decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).
  
  etravirine will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• fexinidazole

  fexinidazole will increase the level or effect of ivacaftor 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.
  
  fexinidazole will increase the level or effect of tezacaftor 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.

• fosphenytoin

  fosphenytoin decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).
  
  fosphenytoin will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• grapefruit

  grapefruit increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid grapefruit, grapefruit juice, or Seville oranges while taking ivacaftor.
  
  grapefruit will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of tezacaftor with grapefruit juice, which contains 1 or more components that moderately inhibit CYP3A, may increase exposure of tezacaftor. Avoid food containing grapefruit or Seville oranges.

• infigratinib

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

• ivosidenib

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

• ivosidenib

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

• larotrectinib

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

• lemborexant

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

• lonafarnib

  lonafarnib will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with sensitive CYP3A substrates. If coadministration unavoidable, monitor for adverse reactions and reduce CYP3A substrate dose in accordance with product labeling.

• lurbinectedin

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

• midazolam intranasal

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

• mifepristone

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

• mitotane

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

• mobocertinib

  ivacaftor will increase the level or effect of mobocertinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If use of moderate CYP3A4 inhibitor unavoidable, reduce mobocertinib dose by ~50% (eg, 160 to 80 mg); closely monitor QTc interval.

• nafcillin

  nafcillin decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).
  
  nafcillin will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• nevirapine

  nevirapine will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  nevirapine, ivacaftor. Other (see comment). Avoid or Use Alternate Drug. Comment: Nevirapine decreases levels of ivacaftor by CYP enzyme induction; whereas, ivacaftor increases levels of efavirenz by inhibiting CYP3A4.

• omaveloxolone

  ivacaftor will increase the level or effect of omaveloxolone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unavoidable, reduce omaveloxolone dose to 100 mg/day. Closely monitor for adverse effects. If adverse effects emerge, further reduce to 50 mg/day.

• oxcarbazepine

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

• oxcarbazepine

  oxcarbazepine decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).

• pacritinib

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

• pemigatinib

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

• pentobarbital

  pentobarbital decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).
  
  pentobarbital will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• pexidartinib

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

• phenobarbital

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

• phenobarbital

  phenobarbital decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).

• phenytoin

  phenytoin decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).
  
  phenytoin will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• primidone

  primidone decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).
  
  primidone will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• rifabutin

  rifabutin decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).
  
  rifabutin will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• rifampin

  rifampin decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).
  
  rifampin will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• rifapentine

  rifapentine decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).
  
  rifapentine will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• rimegepant

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

• St John's Wort

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

• secobarbital

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

• ruxolitinib topical

  ivacaftor increases levels of ruxolitinib topical by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Ivacaftor and its M1 metabolite has the potential to inhibit CYP3A4, may significantly increase systemic exposure to 3A4 substrates.

• selumetinib

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

• siponimod

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

• St John's Wort

  St John's Wort decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).

• tazemetostat

  ivacaftor will increase the level or effect of tazemetostat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of tazemetostat with moderate CYP3A4 inhibitors. If coadministration is unavoidable, reduce tazemetostat current dose (see drug monograph Dosage Modifications).

• tucatinib

  tucatinib will increase the level or effect of ivacaftor 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.
  
  tucatinib will increase the level or effect of tezacaftor 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.

• voxelotor

  voxelotor will increase the level or effect of ivacaftor 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.
  
  voxelotor will increase the level or effect of tezacaftor 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.

Monitor Closely (218)

• acetaminophen

  acetaminophen increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• acetaminophen IV

  acetaminophen IV increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• acetaminophen rectal

  acetaminophen rectal increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• aliskiren

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

• alvimopan

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

• ambrisentan

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

• amiodarone

  amiodarone will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.
  
  ivacaftor increases levels of amiodarone by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  amiodarone will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• amitriptyline

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

• aprepitant

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

• armodafinil

  armodafinil increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• atazanavir

  atazanavir will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  atazanavir will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.

• atogepant

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

• berotralstat

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

• atorvastatin

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

• azelastine

  azelastine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• belzutifan

  belzutifan will decrease the level or effect of ivacaftor 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.

• bendamustine

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

• betamethasone

  betamethasone increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• betamethasone topical

  betamethasone topical increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• betrixaban

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

• bicalutamide

  bicalutamide will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.
  
  bicalutamide increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Reduce ivacaftor dose to 150 mg once daily when coadministered with moderate CYP3A4 inhibitors.

• budesonide

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

• cenobamate

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

• carvedilol

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

• cenobamate

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

• ceritinib

  ivacaftor increases levels of ceritinib by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  ceritinib will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  ceritinib will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.

• chloramphenicol

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

• clarithromycin

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

• chlorzoxazone

  chlorzoxazone increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• cimetidine

  cimetidine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification. .

• ciprofloxacin

  ivacaftor increases levels of ciprofloxacin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  ciprofloxacin increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• clarithromycin

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

• clemastine

  clemastine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• cobicistat

  cobicistat will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  cobicistat will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.

• conivaptan

  conivaptan will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  conivaptan will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.

• crizotinib

  crizotinib will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  crizotinib will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.

• crofelemer

  crofelemer increases levels of ivacaftor 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.

• cyclosporine

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

• cyclosporine

  cyclosporine will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  ivacaftor increases levels of cyclosporine by P-glycoprotein (MDR1) efflux transporter. Modify Therapy/Monitor Closely. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• dabrafenib

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

• danazol

  danazol increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• darunavir

  darunavir will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  darunavir will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.

• daunorubicin

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

• diltiazem

  diltiazem will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. When tezacaftor/ivacaftor is combined with moderate CYP3A4 inhibitors, administer tezacaftor/ivacaftor (100 mg/150 mg) in the morning, every other day. Administer ivacaftor 150 mg alonein the evening, every other day, on alternate days from tezacaftor/ivacaftor.

• desloratadine

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

• desvenlafaxine

  desvenlafaxine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• dexamethasone

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

• dexmedetomidine

  dexmedetomidine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• diazepam intranasal

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

• diclofenac

  diclofenac increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• diclofenac topical

  diclofenac topical increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• digoxin

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

• diltiazem

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

• disulfiram

  disulfiram increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• docetaxel

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

• doxorubicin

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

• doxycycline

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

• dronedarone

  dronedarone will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.
  
  dronedarone will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• drospirenone

  drospirenone increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• duvelisib

  duvelisib will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration with duvelisib increases AUC of a sensitive CYP3A4 substrate which may increase the risk of toxicities of these drugs. Consider reducing the dose of the sensitive CYP3A4 substrate and monitor for signs of toxicities of the coadministered sensitive CYP3A substrate.

• duvelisib

  duvelisib will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  ivacaftor will increase the level or effect of duvelisib by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• edoxaban

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

• efavirenz

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

• elagolix

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

• eletriptan

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

• encorafenib

  encorafenib, tezacaftor. 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.

• elvitegravir/cobicistat/emtricitabine/tenofovir DF

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

• encorafenib

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

• entrectinib

  ivacaftor will increase the level or effect of entrectinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Avoid coadministration of moderate CYP3A4 inhibitors with entrectinib, a CYP3A4 substrate. If coadministration unavoidable, reduce entrectinib dose. Resume previous entrectinib dose after discontinuing moderate CYP3A inhibitor for 3-5 elimination half-lives.

• erythromycin base

  erythromycin base will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  ivacaftor increases levels of erythromycin base by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  erythromycin base will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.

• erythromycin ethylsuccinate

  ivacaftor increases levels of erythromycin ethylsuccinate by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  erythromycin ethylsuccinate will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.
  
  erythromycin ethylsuccinate will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• erythromycin lactobionate

  erythromycin lactobionate will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.
  
  ivacaftor increases levels of erythromycin lactobionate by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  erythromycin lactobionate will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• erythromycin stearate

  erythromycin stearate will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  erythromycin stearate will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.
  
  ivacaftor increases levels of erythromycin stearate by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• estradiol

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

• fedratinib

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

• etoposide

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

• everolimus

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

• fedratinib

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

• fexofenadine

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

• finerenone

  ivacaftor will increase the level or effect of finerenone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Monitor serum potassium during initiation and dosage adjustment of either finererone or moderate CYP3A4 inhibitors. Adjust finererone dosage as needed.

• fluconazole

  fluconazole will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  fluconazole will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.

• fluoxetine

  fluoxetine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• fluvoxamine

  fluvoxamine will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust dose when coadministered with a moderate CYP3A4 inhibitor

• fluvastatin

  fluvastatin increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• fluvoxamine

  fluvoxamine will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with CYP3A4 inhibitors; see ivacaftor prescribing information for precise dosage information

• fosamprenavir

  fosamprenavir will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  ivacaftor increases levels of fosamprenavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  fosamprenavir will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.

• fosaprepitant

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

• fostamatinib

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

• glecaprevir/pibrentasvir

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

• glyburide

  ivacaftor increases levels of glyburide by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  glyburide increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• haloperidol

  haloperidol will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.
  
  haloperidol will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• hydralazine

  hydralazine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• idelalisib

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

• hydrocortisone

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

• idelalisib

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

• iloperidone

  iloperidone will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  iloperidone will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.

• imatinib

  imatinib will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  imatinib will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.

• indinavir

  indinavir will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  ivacaftor increases levels of indinavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  indinavir will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.

• irbesartan

  irbesartan increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• isoniazid

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

• irinotecan

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

• irinotecan liposomal

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

• isavuconazonium sulfate

  ivacaftor will increase the level or effect of isavuconazonium sulfate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• isoniazid

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

• istradefylline

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

• itraconazole

  itraconazole will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.
  
  itraconazole will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• ivermectin

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

• ketoconazole

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

• ketoconazole

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

• lapatinib

  lapatinib will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.
  
  lapatinib will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  ivacaftor increases levels of lapatinib by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• lefamulin

  ivacaftor will increase the level or effect of lefamulin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor for adverse effects if lefamulin is coadministered with moderate CYP3A inhibitors.

• lenacapavir

  lenacapavir will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Lencapavir may increase CYP3A4 substrates initiated within 9 months after last SC dose of lenacapavir, which may increase potential risk of adverse reactions of CYP3A4 substrates.

• lenacapavir

  lenacapavir will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Lencapavir may increase CYP3A4 substrates initiated within 9 months after last SC dose of lenacapavir, which may increase potential risk of adverse reactions of CYP3A4 substrates.

• letermovir

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

• levamlodipine

  ivacaftor will increase the level or effect of levamlodipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration with moderate and strong CYP3A inhibitors results in increased systemic exposure to amlodipine and may require dose reduction. Monitor for symptoms of hypotension and edema when amlodipine is coadministered with CYP3A inhibitors to determine the need for dose adjustment.

• levoketoconazole

  levoketoconazole will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  levoketoconazole will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.

• lidocaine

  ivacaftor increases levels of lidocaine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  ivacaftor increases effects of lidocaine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• lopinavir

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

• lomustine

  lomustine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• loperamide

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

• lopinavir

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

• loratadine

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

• lorlatinib

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

• lovastatin

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

• metronidazole

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

• maraviroc

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

• mavacamten

  ivacaftor will increase the level or effect of mavacamten by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Inititiation of moderate CYP3A4 inhibitors may require decreased mavacamten dose.

• mefloquine

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

• methimazole

  methimazole increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• methoxsalen

  methoxsalen increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• methylprednisolone

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

• metronidazole

  metronidazole increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• micafungin

  micafungin increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• mifepristone

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

• mitomycin

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

• mitotane

  mitotane decreases levels of ivacaftor 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.

• mitoxantrone

  mitoxantrone increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• morphine

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

• naldemedine

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

• nefazodone

  nefazodone will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.
  
  nefazodone will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• nelfinavir

  ivacaftor increases levels of nelfinavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  nelfinavir will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  nelfinavir will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.

• netupitant/palonosetron

  netupitant/palonosetron will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.
  
  netupitant/palonosetron will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• nicardipine

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

• nilotinib

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

• nintedanib

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

• nirmatrelvir/ritonavir

  nirmatrelvir/ritonavir will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce dosage of ivacaftor, elexacaftor/tezacaftor/ivacaftor, or tezacaftor/ivacaftor if coadministered.

• nizatidine

  nizatidine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• olanzapine

  olanzapine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• oliceridine

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

• ondansetron

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

• orphenadrine

  orphenadrine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• oxybutynin

  oxybutynin increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• oxybutynin topical

  oxybutynin topical increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• oxybutynin transdermal

  oxybutynin transdermal increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• paclitaxel

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

• paclitaxel protein bound

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

• paroxetine

  paroxetine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• pazopanib

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

• pentamidine

  pentamidine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• pilocarpine

  pilocarpine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• posaconazole

  ivacaftor increases levels of posaconazole by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  posaconazole will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.
  
  posaconazole will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• pravastatin

  ivacaftor increases levels of pravastatin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  pravastatin increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• quinupristin/dalfopristin

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

• prednisone

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

• progesterone intravaginal gel

  progesterone intravaginal gel increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• progesterone micronized

  progesterone micronized increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• propofol

  propofol increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• quinidine

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

• quinupristin/dalfopristin

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

• ranolazine

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

• ribociclib

  ribociclib will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  ribociclib will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.

• rifampin

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

• ritonavir

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

• rifaximin

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

• rimegepant

  ivacaftor will increase the level or effect of rimegepant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Avoid repeating rimegepant dose within 48 hr if coadministered with a moderate CYP3A4 inhibitor.

• risperidone

  ivacaftor increases levels of risperidone by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  risperidone increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• ritonavir

  ritonavir will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  ivacaftor increases levels of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• rucaparib

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

• saquinavir

  saquinavir will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  saquinavir will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.
  
  ivacaftor increases levels of saquinavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• saxagliptin

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

• schisandra

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

• selegiline

  selegiline increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• sertraline

  sertraline will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  sertraline will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.

• silodosin

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

• stiripentol

  stiripentol, tezacaftor. 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.

• simvastatin

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

• sirolimus

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

• sitagliptin

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

• stiripentol

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

• sulconazole

  sulconazole increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• tacrolimus

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

• talazoparib

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

• tamoxifen

  tamoxifen increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• tazemetostat

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

• tecovirimat

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

• temsirolimus

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

• tetracycline

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

• teniposide

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

• testosterone

  ivacaftor increases levels of testosterone by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  testosterone increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• testosterone buccal system

  testosterone buccal system increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• testosterone topical

  testosterone topical increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• tipranavir

  tipranavir will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  tipranavir will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.

• tolvaptan

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

• verapamil

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

• topotecan

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

• tranylcypromine

  tranylcypromine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• valproic acid

  valproic acid increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• vardenafil

  ivacaftor will increase the level or effect of vardenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Vardenafil dose may need to be reduced if coadministered with moderate or strong CYP3A4 inhibitors

• venetoclax

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

• verapamil

  verapamil will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  ivacaftor increases levels of verapamil by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• vinblastine

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

• vincristine

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

• vincristine liposomal

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

• voclosporin

  ivacaftor will increase the level or effect of voclosporin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce voclosporin daily dosage to 15.8 mg PO in AM and 7.9 mg PO in PM.

• voriconazole

  voriconazole will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.
  
  voriconazole will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• zafirlukast

  zafirlukast increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• zanubrutinib

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

• ziprasidone

  ziprasidone increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

Minor (4)

• acetazolamide

  acetazolamide increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
  
  acetazolamide will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• anastrozole

  anastrozole will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
  
  anastrozole increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• cyclophosphamide

  cyclophosphamide will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
  
  cyclophosphamide will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• larotrectinib

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

• abametapir

  Serious - Use Alternative (2)abametapir increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. For 2 weeks after abametapir application, avoid taking drugs that are CYP3A4 substrates. If not feasible, avoid use of abametapir.
  
  abametapir will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. For 2 weeks after abametapir application, avoid taking drugs that are CYP3A4 substrates. If not feasible, avoid use of abametapir.

• acetaminophen

  Monitor Closely (1)acetaminophen increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• acetaminophen IV

  Monitor Closely (1)acetaminophen IV increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• acetaminophen rectal

  Monitor Closely (1)acetaminophen rectal increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• acetazolamide

  Minor (2)acetazolamide increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
  
  acetazolamide will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• aliskiren

  Monitor Closely (1)ivacaftor increases levels of aliskiren by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• alvimopan

  Monitor Closely (1)ivacaftor increases levels of alvimopan by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• ambrisentan

  Monitor Closely (1)ivacaftor increases levels of ambrisentan by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• amiodarone

  Monitor Closely (3)amiodarone will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.
  
  ivacaftor increases levels of amiodarone by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  amiodarone will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• amitriptyline

  Monitor Closely (1)ivacaftor increases levels of amitriptyline by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• amobarbital

  Serious - Use Alternative (1)amobarbital will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• anastrozole

  Minor (2)anastrozole will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
  
  anastrozole increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• apalutamide

  Serious - Use Alternative (2)apalutamide will decrease the level or effect of ivacaftor 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.
  
  apalutamide will decrease the level or effect of tezacaftor 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.

• aprepitant

  Monitor Closely (1)aprepitant will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.

• armodafinil

  Monitor Closely (1)armodafinil increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• atazanavir

  Monitor Closely (2)atazanavir will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  atazanavir will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.

• atogepant

  Monitor Closely (1)ivacaftor will increase the level or effect of atogepant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• atorvastatin

  Monitor Closely (1)ivacaftor increases levels of atorvastatin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• avapritinib

  Serious - Use Alternative (1)ivacaftor will increase the level or effect of avapritinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of avapritinib with strong CYP3A4 inhibitors.

• azelastine

  Monitor Closely (1)azelastine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• belzutifan

  Monitor Closely (1)belzutifan will decrease the level or effect of ivacaftor 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.

• bendamustine

  Monitor Closely (1)ivacaftor increases levels of bendamustine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• berotralstat

  Monitor Closely (1)tezacaftor increases levels of berotralstat by P-glycoprotein (MDR1) efflux transporter. Modify Therapy/Monitor Closely. Reduced berotralstat dose to 110 mg/day when coadministered with P-gp inhibitors.

• betamethasone

  Monitor Closely (1)betamethasone increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• betamethasone topical

  Monitor Closely (1)betamethasone topical increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• betrixaban

  Monitor Closely (1)ivacaftor increases levels of betrixaban by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• bicalutamide

  Monitor Closely (2)bicalutamide will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.
  
  bicalutamide increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Reduce ivacaftor dose to 150 mg once daily when coadministered with moderate CYP3A4 inhibitors.

• bosentan

  Serious - Use Alternative (2)bosentan will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  bosentan decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).

• budesonide

  Monitor Closely (1)ivacaftor increases levels of budesonide by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• butabarbital

  Serious - Use Alternative (1)butabarbital will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• butalbital

  Serious - Use Alternative (1)butalbital will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• carbamazepine

  Serious - Use Alternative (2)carbamazepine will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  carbamazepine decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).

• carvedilol

  Monitor Closely (1)ivacaftor increases levels of carvedilol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• cenobamate

  Monitor Closely (2)cenobamate will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Increase dose of CYP3A4 substrate, as needed, when coadministered with cenobamate.
  
  cenobamate will decrease the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Increase dose of CYP3A4 substrate, as needed, when coadministered with cenobamate.

• ceritinib

  Monitor Closely (3)ivacaftor increases levels of ceritinib by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  ceritinib will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  ceritinib will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.

• chloramphenicol

  Monitor Closely (1)chloramphenicol will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.Serious - Use Alternative (1)chloramphenicol will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• chlorzoxazone

  Monitor Closely (1)chlorzoxazone increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• cimetidine

  Monitor Closely (1)cimetidine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification. .Serious - Use Alternative (1)ivacaftor increases levels of cimetidine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• ciprofloxacin

  Monitor Closely (2)ivacaftor increases levels of ciprofloxacin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  ciprofloxacin increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• clarithromycin

  Monitor Closely (2)clarithromycin will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  clarithromycin will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.

• clemastine

  Monitor Closely (1)clemastine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• cobicistat

  Monitor Closely (2)cobicistat will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  cobicistat will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.

• colchicine

  Serious - Use Alternative (1)ivacaftor increases levels of colchicine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. Avoid use of colchicine with P-gp inhibitors. If coadministration is necessary, decrease colchicine dose or frequency as recommended in prescribing information. Use of any colchicine product in conjunction with P-gp inhibitors is contraindicated in patients with renal or hepatic impairment. .

• conivaptan

  Monitor Closely (2)conivaptan will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  conivaptan will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.

• crizotinib

  Monitor Closely (2)crizotinib will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  crizotinib will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.

• crofelemer

  Monitor Closely (1)crofelemer increases levels of ivacaftor 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

  Minor (2)cyclophosphamide will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
  
  cyclophosphamide will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• cyclosporine

  Monitor Closely (3)cyclosporine will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.
  
  cyclosporine will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  ivacaftor increases levels of cyclosporine by P-glycoprotein (MDR1) efflux transporter. Modify Therapy/Monitor Closely. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• dabigatran

  Serious - Use Alternative (1)ivacaftor increases levels of dabigatran by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. Atrial fibrillation: Avoid coadministering dabigatran with P-gp inhibitors if CrCl <30 mL/min. DVT/PE treatment: Avoid coadministering dabigatran with P-gp inhibitors if CrCl <50 mL/min.

• dabrafenib

  Monitor Closely (1)dabrafenib will decrease the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.Serious - Use Alternative (1)dabrafenib will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• danazol

  Monitor Closely (1)danazol increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• darunavir

  Monitor Closely (2)darunavir will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  darunavir will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.

• daunorubicin

  Monitor Closely (1)ivacaftor increases levels of daunorubicin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• desloratadine

  Monitor Closely (1)ivacaftor increases levels of desloratadine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• desvenlafaxine

  Monitor Closely (1)desvenlafaxine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• dexamethasone

  Monitor Closely (1)ivacaftor increases levels of dexamethasone by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.Serious - Use Alternative (2)dexamethasone will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  dexamethasone decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).

• dexmedetomidine

  Monitor Closely (1)dexmedetomidine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• diazepam intranasal

  Monitor Closely (1)ivacaftor will increase the level or effect of diazepam intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Strong or moderate CYP3A4 inhibitors may decrease rate of diazepam elimination, thereby increasing adverse reactions to diazepam.

• diclofenac

  Monitor Closely (1)diclofenac increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• diclofenac topical

  Monitor Closely (1)diclofenac topical increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• digoxin

  Monitor Closely (1)ivacaftor increases levels of digoxin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• diltiazem

  Monitor Closely (2)diltiazem will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  diltiazem will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. When tezacaftor/ivacaftor is combined with moderate CYP3A4 inhibitors, administer tezacaftor/ivacaftor (100 mg/150 mg) in the morning, every other day. Administer ivacaftor 150 mg alonein the evening, every other day, on alternate days from tezacaftor/ivacaftor.

• disulfiram

  Monitor Closely (1)disulfiram increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• docetaxel

  Monitor Closely (1)ivacaftor increases levels of docetaxel by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• doxorubicin

  Monitor Closely (1)ivacaftor increases levels of doxorubicin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• doxycycline

  Monitor Closely (1)doxycycline will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.

• dronedarone

  Monitor Closely (2)dronedarone will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  dronedarone will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.

• drospirenone

  Monitor Closely (1)drospirenone increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• duvelisib

  Monitor Closely (3)ivacaftor will increase the level or effect of duvelisib by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  duvelisib will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration with duvelisib increases AUC of a sensitive CYP3A4 substrate which may increase the risk of toxicities of these drugs. Consider reducing the dose of the sensitive CYP3A4 substrate and monitor for signs of toxicities of the coadministered sensitive CYP3A substrate.
  
  duvelisib will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• edoxaban

  Monitor Closely (1)ivacaftor will increase the level or effect of edoxaban by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Dose adjustment may be required with strong P-gp inhibitors. DVT/PE treatment: Decrease dose to 30 mg PO once daily. NVAF: No dose reduction recommended

• efavirenz

  Monitor Closely (1)efavirenz will decrease the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (2)efavirenz will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  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 .

• elacestrant

  Serious - Use Alternative (1)ivacaftor will increase the level or effect of elacestrant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• elagolix

  Monitor Closely (2)elagolix decreases levels of tezacaftor 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.
  
  elagolix decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Elagolix is a weak-to-moderate CYP3A4 inducer. Monitor CYP3A substrates if coadministered. Consider increasing CYP3A substrate dose if needed.

• eletriptan

  Monitor Closely (1)ivacaftor increases levels of eletriptan by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• elvitegravir/cobicistat/emtricitabine/tenofovir DF

  Monitor Closely (1)elvitegravir/cobicistat/emtricitabine/tenofovir DF will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• encorafenib

  Monitor Closely (2)encorafenib, tezacaftor. 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.
  
  encorafenib will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• entrectinib

  Monitor Closely (1)ivacaftor will increase the level or effect of entrectinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Avoid coadministration of moderate CYP3A4 inhibitors with entrectinib, a CYP3A4 substrate. If coadministration unavoidable, reduce entrectinib dose. Resume previous entrectinib dose after discontinuing moderate CYP3A inhibitor for 3-5 elimination half-lives.

• enzalutamide

  Serious - Use Alternative (2)enzalutamide will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  enzalutamide will decrease the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• erythromycin base

  Monitor Closely (3)erythromycin base will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  ivacaftor increases levels of erythromycin base by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  erythromycin base will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.

• erythromycin ethylsuccinate

  Monitor Closely (3)ivacaftor increases levels of erythromycin ethylsuccinate by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  erythromycin ethylsuccinate will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.
  
  erythromycin ethylsuccinate will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• erythromycin lactobionate

  Monitor Closely (3)erythromycin lactobionate will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.
  
  ivacaftor increases levels of erythromycin lactobionate by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  erythromycin lactobionate will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• erythromycin stearate

  Monitor Closely (3)erythromycin stearate will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  erythromycin stearate will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.
  
  ivacaftor increases levels of erythromycin stearate by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• eslicarbazepine acetate

  Serious - Use Alternative (2)eslicarbazepine acetate will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  eslicarbazepine acetate will decrease the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold)

• estradiol

  Monitor Closely (1)ivacaftor increases levels of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• etoposide

  Monitor Closely (1)ivacaftor increases levels of etoposide by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• etravirine

  Serious - Use Alternative (2)etravirine decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).
  
  etravirine will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• everolimus

  Monitor Closely (1)ivacaftor increases levels of everolimus by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• fedratinib

  Monitor Closely (2)fedratinib will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  fedratinib will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP3A4 substrates as necessary.

• fexinidazole

  Serious - Use Alternative (2)fexinidazole will increase the level or effect of ivacaftor 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.
  
  fexinidazole will increase the level or effect of tezacaftor 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.

• fexofenadine

  Monitor Closely (1)ivacaftor increases levels of fexofenadine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• finerenone

  Monitor Closely (1)ivacaftor will increase the level or effect of finerenone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Monitor serum potassium during initiation and dosage adjustment of either finererone or moderate CYP3A4 inhibitors. Adjust finererone dosage as needed.

• fluconazole

  Monitor Closely (2)fluconazole will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  fluconazole will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.

• fluoxetine

  Monitor Closely (1)fluoxetine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• fluvastatin

  Monitor Closely (1)fluvastatin increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• fluvoxamine

  Monitor Closely (2)fluvoxamine will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with CYP3A4 inhibitors; see ivacaftor prescribing information for precise dosage information
  
  fluvoxamine will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust dose when coadministered with a moderate CYP3A4 inhibitor

• fosamprenavir

  Monitor Closely (3)fosamprenavir will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  ivacaftor increases levels of fosamprenavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  fosamprenavir will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.

• fosaprepitant

  Monitor Closely (1)fosaprepitant will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.

• fosphenytoin

  Serious - Use Alternative (2)fosphenytoin decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).
  
  fosphenytoin will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• fostamatinib

  Monitor Closely (1)fostamatinib will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• glecaprevir/pibrentasvir

  Monitor Closely (1)ivacaftor will increase the level or effect of glecaprevir/pibrentasvir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• glyburide

  Monitor Closely (2)ivacaftor increases levels of glyburide by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  glyburide increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• grapefruit

  Serious - Use Alternative (2)grapefruit increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid grapefruit, grapefruit juice, or Seville oranges while taking ivacaftor.
  
  grapefruit will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of tezacaftor with grapefruit juice, which contains 1 or more components that moderately inhibit CYP3A, may increase exposure of tezacaftor. Avoid food containing grapefruit or Seville oranges.

• haloperidol

  Monitor Closely (2)haloperidol will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.
  
  haloperidol will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• hydralazine

  Monitor Closely (1)hydralazine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• hydrocortisone

  Monitor Closely (1)ivacaftor increases levels of hydrocortisone by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• idelalisib

  Monitor Closely (2)idelalisib will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.
  
  idelalisib will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• iloperidone

  Monitor Closely (2)iloperidone will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  iloperidone will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.

• imatinib

  Monitor Closely (2)imatinib will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  imatinib will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.

• indinavir

  Monitor Closely (3)indinavir will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  ivacaftor increases levels of indinavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  indinavir will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.

• infigratinib

  Serious - Use Alternative (1)ivacaftor will increase the level or effect of infigratinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• irbesartan

  Monitor Closely (1)irbesartan increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• irinotecan

  Monitor Closely (1)ivacaftor increases levels of irinotecan by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• irinotecan liposomal

  Monitor Closely (1)ivacaftor increases levels of irinotecan liposomal by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• isavuconazonium sulfate

  Monitor Closely (1)ivacaftor will increase the level or effect of isavuconazonium sulfate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• isoniazid

  Monitor Closely (2)isoniazid will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  isoniazid will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.

• istradefylline

  Monitor Closely (2)istradefylline will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. 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. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  istradefylline will increase the level or effect of tezacaftor 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.

• itraconazole

  Monitor Closely (2)itraconazole will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.
  
  itraconazole will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• ivermectin

  Monitor Closely (1)ivacaftor increases levels of ivermectin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• ivosidenib

  Serious - Use Alternative (2)ivosidenib will decrease the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sensitive CYP3A4 substrates with ivosidenib or replace with alternative therapies. If coadministration is unavoidable, monitor patients for loss of therapeutic effect of these drugs.
  
  ivosidenib will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sensitive CYP3A4 substrates with ivosidenib or replace with alternative therapies. If coadministration is unavoidable, monitor patients for loss of therapeutic effect of these drugs.

• ketoconazole

  Monitor Closely (2)ketoconazole will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.
  
  ketoconazole will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• lapatinib

  Monitor Closely (3)lapatinib will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.
  
  lapatinib will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  ivacaftor increases levels of lapatinib by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• larotrectinib

  Serious - Use Alternative (1)ivacaftor will decrease the level or effect of larotrectinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.Minor (1)larotrectinib will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• lefamulin

  Monitor Closely (1)ivacaftor will increase the level or effect of lefamulin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor for adverse effects if lefamulin is coadministered with moderate CYP3A inhibitors.

• lemborexant

  Serious - Use Alternative (1)ivacaftor will increase the level or effect of lemborexant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of lemborexant with moderate or strong CYP3A inhibitors.

• lenacapavir

  Monitor Closely (2)lenacapavir will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Lencapavir may increase CYP3A4 substrates initiated within 9 months after last SC dose of lenacapavir, which may increase potential risk of adverse reactions of CYP3A4 substrates.
  
  lenacapavir will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Lencapavir may increase CYP3A4 substrates initiated within 9 months after last SC dose of lenacapavir, which may increase potential risk of adverse reactions of CYP3A4 substrates.

• letermovir

  Monitor Closely (1)letermovir will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• levamlodipine

  Monitor Closely (1)ivacaftor will increase the level or effect of levamlodipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration with moderate and strong CYP3A inhibitors results in increased systemic exposure to amlodipine and may require dose reduction. Monitor for symptoms of hypotension and edema when amlodipine is coadministered with CYP3A inhibitors to determine the need for dose adjustment.

• levoketoconazole

  Monitor Closely (2)levoketoconazole will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  levoketoconazole will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.

• lidocaine

  Monitor Closely (2)ivacaftor increases levels of lidocaine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  ivacaftor increases effects of lidocaine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• lomustine

  Monitor Closely (1)lomustine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• lonafarnib

  Contraindicated (1)ivacaftor will increase the level or effect of lonafarnib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Lonafarnib is a sensitive CYP3A4 substrate. Coadministration with strong or moderate CYP3A4 inhibitors is contraindicated. Serious - Use Alternative (1)lonafarnib will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with sensitive CYP3A substrates. If coadministration unavoidable, monitor for adverse reactions and reduce CYP3A substrate dose in accordance with product labeling.

• loperamide

  Monitor Closely (1)ivacaftor increases levels of loperamide by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• lopinavir

  Monitor Closely (2)lopinavir will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.
  
  lopinavir will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• loratadine

  Monitor Closely (1)ivacaftor increases levels of loratadine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• lorlatinib

  Monitor Closely (2)lorlatinib will decrease the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
  
  lorlatinib will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• lovastatin

  Monitor Closely (1)ivacaftor increases levels of lovastatin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• lurbinectedin

  Serious - Use Alternative (1)ivacaftor will increase the level or effect of lurbinectedin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• maraviroc

  Monitor Closely (1)ivacaftor increases levels of maraviroc by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• mavacamten

  Monitor Closely (1)ivacaftor will increase the level or effect of mavacamten by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Inititiation of moderate CYP3A4 inhibitors may require decreased mavacamten dose.

• mefloquine

  Monitor Closely (1)ivacaftor increases levels of mefloquine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• methimazole

  Monitor Closely (1)methimazole increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• methoxsalen

  Monitor Closely (1)methoxsalen increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• methylprednisolone

  Monitor Closely (1)ivacaftor increases levels of methylprednisolone by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• metronidazole

  Monitor Closely (2)metronidazole will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.
  
  metronidazole increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• micafungin

  Monitor Closely (1)micafungin increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• midazolam intranasal

  Serious - Use Alternative (1)ivacaftor will increase the level or effect of midazolam intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of moderate CYP3A4 inhibitors with midazolam intranasal causes higher midazolam systemic exposure, which may prolong sedation.

• mifepristone

  Monitor Closely (1)mifepristone will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.Serious - Use Alternative (1)mifepristone will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• mitomycin

  Monitor Closely (1)ivacaftor increases levels of mitomycin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• mitotane

  Monitor Closely (1)mitotane decreases levels of ivacaftor 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.Serious - Use Alternative (1)mitotane will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• mitoxantrone

  Monitor Closely (1)mitoxantrone increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• mobocertinib

  Serious - Use Alternative (1)ivacaftor will increase the level or effect of mobocertinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If use of moderate CYP3A4 inhibitor unavoidable, reduce mobocertinib dose by ~50% (eg, 160 to 80 mg); closely monitor QTc interval.

• morphine

  Monitor Closely (1)ivacaftor increases levels of morphine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• nafcillin

  Serious - Use Alternative (2)nafcillin decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).
  
  nafcillin will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• naldemedine

  Monitor Closely (1)ivacaftor increases levels of naldemedine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Monitor naldemedine for potential adverse effects if coadministered with P-gp inhibitors.

• nefazodone

  Monitor Closely (2)nefazodone will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.
  
  nefazodone will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• nelfinavir

  Monitor Closely (3)ivacaftor increases levels of nelfinavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  nelfinavir will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  nelfinavir will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.

• netupitant/palonosetron

  Monitor Closely (2)netupitant/palonosetron will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.
  
  netupitant/palonosetron will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• nevirapine

  Serious - Use Alternative (2)nevirapine will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  nevirapine, ivacaftor. Other (see comment). Avoid or Use Alternate Drug. Comment: Nevirapine decreases levels of ivacaftor by CYP enzyme induction; whereas, ivacaftor increases levels of efavirenz by inhibiting CYP3A4.

• nicardipine

  Monitor Closely (1)nicardipine will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.

• nilotinib

  Monitor Closely (1)ivacaftor increases levels of nilotinib by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• nintedanib

  Monitor Closely (1)ivacaftor increases levels of nintedanib by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. If nintedanib adverse effects occur, management may require interruption, dose reduction, or discontinuation of therapy .

• nirmatrelvir/ritonavir

  Monitor Closely (1)nirmatrelvir/ritonavir will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce dosage of ivacaftor, elexacaftor/tezacaftor/ivacaftor, or tezacaftor/ivacaftor if coadministered.

• nizatidine

  Monitor Closely (1)nizatidine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• olanzapine

  Monitor Closely (1)olanzapine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• oliceridine

  Monitor Closely (1)ivacaftor will increase the level or effect of oliceridine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. If concomitant use is necessary, may require less frequent oliceridine dosing. Closely monitor for respiratory depression and sedation and titrate subsequent doses accordingly. If inhibitor is discontinued, consider increase oliceridine dosage until stable drug effects are achieved. Monitor for signs of opioid withdrawal.

• omaveloxolone

  Serious - Use Alternative (1)ivacaftor will increase the level or effect of omaveloxolone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unavoidable, reduce omaveloxolone dose to 100 mg/day. Closely monitor for adverse effects. If adverse effects emerge, further reduce to 50 mg/day.

• ondansetron

  Monitor Closely (1)ivacaftor increases levels of ondansetron by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• orphenadrine

  Monitor Closely (1)orphenadrine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• oxcarbazepine

  Serious - Use Alternative (2)oxcarbazepine decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).
  
  oxcarbazepine will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• oxybutynin

  Monitor Closely (1)oxybutynin increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• oxybutynin topical

  Monitor Closely (1)oxybutynin topical increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• oxybutynin transdermal

  Monitor Closely (1)oxybutynin transdermal increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• paclitaxel

  Monitor Closely (1)ivacaftor increases levels of paclitaxel by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• paclitaxel protein bound

  Monitor Closely (1)ivacaftor increases levels of paclitaxel protein bound by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• pacritinib

  Serious - Use Alternative (1)ivacaftor will increase the level or effect of pacritinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• paroxetine

  Monitor Closely (1)paroxetine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• pazopanib

  Monitor Closely (1)ivacaftor increases levels of pazopanib by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• pemigatinib

  Serious - Use Alternative (1)ivacaftor will increase the level or effect of pemigatinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with strong or moderate CYP3A4 inhibitors is unavoidable, reduce pemigatinib dose (refer to drug monograph dosage modifications). After discontinuing the CYP3A4 inhibitor for 3 elimination half-lives, may resume previous pemigatinib dose.

• pentamidine

  Monitor Closely (1)pentamidine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• pentobarbital

  Serious - Use Alternative (2)pentobarbital decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).
  
  pentobarbital will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• pexidartinib

  Serious - Use Alternative (1)ivacaftor will increase the level or effect of pexidartinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with strong or moderate CYP3A4 inhibitors is unavoidable, reduce pexidartinib dose (refer to drug monograph dosage modifications). After discontinuing the CYP3A4 inhibitor for 3 elimination half-lives, may resume previous pexidartinib dose.

• phenobarbital

  Serious - Use Alternative (2)phenobarbital will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  phenobarbital decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).

• phenytoin

  Serious - Use Alternative (2)phenytoin decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).
  
  phenytoin will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• pilocarpine

  Monitor Closely (1)pilocarpine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• posaconazole

  Monitor Closely (3)ivacaftor increases levels of posaconazole by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  posaconazole will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.
  
  posaconazole will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• pravastatin

  Monitor Closely (2)ivacaftor increases levels of pravastatin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  pravastatin increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• prednisone

  Monitor Closely (1)ivacaftor increases levels of prednisone by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• primidone

  Serious - Use Alternative (2)primidone decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).
  
  primidone will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• progesterone intravaginal gel

  Monitor Closely (1)progesterone intravaginal gel increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• progesterone micronized

  Monitor Closely (1)progesterone micronized increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• propofol

  Monitor Closely (1)propofol increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• quinidine

  Monitor Closely (1)ivacaftor increases levels of quinidine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• quinupristin/dalfopristin

  Monitor Closely (2)quinupristin/dalfopristin will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  quinupristin/dalfopristin will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.

• ranolazine

  Monitor Closely (1)ivacaftor increases levels of ranolazine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• ribociclib

  Monitor Closely (2)ribociclib will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  ribociclib will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.

• rifabutin

  Serious - Use Alternative (2)rifabutin decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).
  
  rifabutin will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• rifampin

  Monitor Closely (1)ivacaftor increases levels of rifampin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.Serious - Use Alternative (2)rifampin decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).
  
  rifampin will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• rifapentine

  Serious - Use Alternative (2)rifapentine decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).
  
  rifapentine will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• rifaximin

  Monitor Closely (1)ivacaftor increases levels of rifaximin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• rimegepant

  Monitor Closely (1)ivacaftor will increase the level or effect of rimegepant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Avoid repeating rimegepant dose within 48 hr if coadministered with a moderate CYP3A4 inhibitor.Serious - Use Alternative (1)ivacaftor will increase the level or effect of rimegepant by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug.

• risperidone

  Monitor Closely (2)ivacaftor increases levels of risperidone by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  risperidone increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• ritonavir

  Monitor Closely (3)ivacaftor increases levels of ritonavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  ritonavir will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  ritonavir will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.

• rucaparib

  Monitor Closely (2)rucaparib will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust dosage of CYP3A4 substrates, if clinically indicated.
  
  rucaparib will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust dosage of CYP3A4 substrates, if clinically indicated.

• ruxolitinib topical

  Serious - Use Alternative (1)ivacaftor increases levels of ruxolitinib topical by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Ivacaftor and its M1 metabolite has the potential to inhibit CYP3A4, may significantly increase systemic exposure to 3A4 substrates.

• saquinavir

  Monitor Closely (3)saquinavir will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  saquinavir will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.
  
  ivacaftor increases levels of saquinavir by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• saxagliptin

  Monitor Closely (1)ivacaftor increases levels of saxagliptin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• schisandra

  Monitor Closely (1)schisandra will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.

• secobarbital

  Serious - Use Alternative (1)secobarbital will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• selegiline

  Monitor Closely (1)selegiline increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• selumetinib

  Serious - Use Alternative (1)ivacaftor will increase the level or effect of selumetinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with strong or moderate CYP3A4 inhibitors cannot be avoided, reduce selumetinib dosage (refer to selumetinib monograph for further information). After discontinuation of the strong or moderate CYP3A4 inhibitor for 3 elimination half-lives, resume selumetinib dose that was taken before initiating the inhibitor.

• sertraline

  Monitor Closely (2)sertraline will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  sertraline will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.

• silodosin

  Monitor Closely (1)ivacaftor increases levels of silodosin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• simvastatin

  Monitor Closely (1)ivacaftor increases levels of simvastatin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• siponimod

  Serious - Use Alternative (1)ivacaftor will increase the level or effect of siponimod by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of siponimod with a moderate or strong CYP3A4 inhibitor PLUS a moderate or strong CYP2C9 inhibitor is not recommended.

• sirolimus

  Monitor Closely (1)ivacaftor increases levels of sirolimus by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• sitagliptin

  Monitor Closely (1)ivacaftor increases levels of sitagliptin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• St John's Wort

  Serious - Use Alternative (1)St John's Wort decreases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with strong CYP3A4 inducers; systemic exposure of ivacaftor substantially reduced (ie, ~9-fold).

• stiripentol

  Monitor Closely (2)stiripentol will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  stiripentol, tezacaftor. 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.

• sulconazole

  Monitor Closely (1)sulconazole increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• tacrolimus

  Monitor Closely (1)ivacaftor increases levels of tacrolimus by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• talazoparib

  Monitor Closely (1)ivacaftor will increase the level or effect of talazoparib by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• tamoxifen

  Monitor Closely (1)tamoxifen increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• tazemetostat

  Monitor Closely (2)tazemetostat will decrease the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
  
  tazemetostat will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)ivacaftor will increase the level or effect of tazemetostat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of tazemetostat with moderate CYP3A4 inhibitors. If coadministration is unavoidable, reduce tazemetostat current dose (see drug monograph Dosage Modifications).

• tecovirimat

  Monitor Closely (2)tecovirimat will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Tecovirimat is a weak CYP3A4 inducer. Monitor sensitive CYP3A4 substrates for effectiveness if coadministered.
  
  tecovirimat will decrease the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Tecovirimat is a weak CYP3A4 inducer. Monitor sensitive CYP3A4 substrates for effectiveness if coadministered.

• temsirolimus

  Monitor Closely (1)ivacaftor increases levels of temsirolimus by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• teniposide

  Monitor Closely (1)ivacaftor increases levels of teniposide by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• testosterone

  Monitor Closely (2)ivacaftor increases levels of testosterone by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
  
  testosterone increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• testosterone buccal system

  Monitor Closely (1)testosterone buccal system increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• testosterone topical

  Monitor Closely (1)testosterone topical increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• tetracycline

  Monitor Closely (1)tetracycline will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.

• tipranavir

  Monitor Closely (2)tipranavir will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  tipranavir will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.

• tolvaptan

  Monitor Closely (1)ivacaftor increases levels of tolvaptan by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• topotecan

  Monitor Closely (1)ivacaftor increases levels of topotecan by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• tranylcypromine

  Monitor Closely (1)tranylcypromine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• tucatinib

  Serious - Use Alternative (2)tucatinib will increase the level or effect of ivacaftor 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.
  
  tucatinib will increase the level or effect of tezacaftor 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.

• valproic acid

  Monitor Closely (1)valproic acid increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• vardenafil

  Monitor Closely (1)ivacaftor will increase the level or effect of vardenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Vardenafil dose may need to be reduced if coadministered with moderate or strong CYP3A4 inhibitors

• venetoclax

  Monitor Closely (1)ivacaftor increases levels of venetoclax by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• verapamil

  Monitor Closely (3)verapamil will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.
  
  verapamil will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.
  
  ivacaftor increases levels of verapamil by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• vinblastine

  Monitor Closely (1)ivacaftor increases levels of vinblastine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• vincristine

  Monitor Closely (1)ivacaftor increases levels of vincristine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• vincristine liposomal

  Monitor Closely (1)ivacaftor increases levels of vincristine liposomal by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• voclosporin

  Monitor Closely (1)ivacaftor will increase the level or effect of voclosporin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce voclosporin daily dosage to 15.8 mg PO in AM and 7.9 mg PO in PM.

• voriconazole

  Monitor Closely (2)voriconazole will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a strong CYP3A inhibitor.
  
  voriconazole will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with strong CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• voxelotor

  Serious - Use Alternative (2)voxelotor will increase the level or effect of ivacaftor 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.
  
  voxelotor will increase the level or effect of tezacaftor 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.

• zafirlukast

  Monitor Closely (1)zafirlukast increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• zanubrutinib

  Monitor Closely (1)ivacaftor will increase the level or effect of zanubrutinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce zanubrutinib dose when coadministered with a moderate CYP3A4 inhibitor. Interrupt dose as recommended for adverse reactions. After discontinuing the CYP3A4 inhibitor, resume previous dose of zanubrutinib. See zanubrutinib Dosage Modifications for precise recommendation.

• ziprasidone

  Monitor Closely (1)ziprasidone increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .