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.ivosidenibivosidenib 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.larotrectinibivacaftor will decrease the level or effect of larotrectinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.lemborexantivacaftor 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.lonafarniblonafarnib 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.lurbinectedinivacaftor will increase the level or effect of lurbinectedin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.midazolam intranasalivacaftor 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.mifepristonemifepristone will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.mitotanemitotane will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.mobocertinibivacaftor 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.nafcillinnafcillin 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.nevirapinenevirapine 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.omaveloxoloneivacaftor 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. oxcarbazepineoxcarbazepine will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.oxcarbazepineoxcarbazepine 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).pacritinibivacaftor will increase the level or effect of pacritinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.pemigatinibivacaftor 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.pentobarbitalpentobarbital 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.pexidartinibivacaftor 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.phenobarbitalphenobarbital will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.phenobarbitalphenobarbital 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).phenytoinphenytoin 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.primidoneprimidone 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.rifabutinrifabutin 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.rifampinrifampin 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.rifapentinerifapentine 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.rimegepantivacaftor will increase the level or effect of rimegepant by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug.St John's WortSt John's Wort will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.secobarbitalsecobarbital will decrease the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.ruxolitinib topicalivacaftor 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.selumetinibivacaftor 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.siponimodivacaftor 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 WortSt 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).tazemetostativacaftor 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). tucatinibtucatinib 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.voxelotorvoxelotor 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 (219)acetaminophenacetaminophen increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .acetaminophen IVacetaminophen IV increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .acetaminophen rectalacetaminophen rectal increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .aliskirenivacaftor 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.alvimopanivacaftor 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.ambrisentanivacaftor 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.amiodaroneamiodarone 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.amitriptylineivacaftor 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.aprepitantaprepitant 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.armodafinilarmodafinil increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .atazanaviratazanavir 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.atogepantivacaftor will increase the level or effect of atogepant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.berotralstattezacaftor 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.atorvastatinivacaftor 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.azelastineazelastine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .belzutifanbelzutifan 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.bendamustineivacaftor 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.betamethasonebetamethasone increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .betamethasone topicalbetamethasone topical increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor