affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.trazodonezafirlukast will increase the level or effect of trazodone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.vinblastinezafirlukast will increase the level or effect of vinblastine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.vincristinezafirlukast will increase the level or effect of vincristine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.vincristine liposomalzafirlukast will increase the level or effect of vincristine liposomal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.vinorelbinezafirlukast will increase the level or effect of vinorelbine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.voriconazolezafirlukast will increase the level or effect of voriconazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.ziprasidonezafirlukast will increase the level or effect of ziprasidone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.zolpidemzafirlukast will increase the level or effect of zolpidem by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.zonisamidezafirlukast will increase the level or effect of zonisamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.alfentanilMinor (1)zafirlukast will increase the level or effect of alfentanil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.alfuzosinMinor (1)zafirlukast will increase the level or effect of alfuzosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.almotriptanMonitor Closely (1)zafirlukast will increase the level or effect of almotriptan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.alosetronMinor (2)zafirlukast will increase the level or effect of alosetron by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown. zafirlukast will increase the level or effect of alosetron by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.alpelisibMonitor Closely (1)alpelisib will decrease the level or effect of zafirlukast by affecting hepatic enzyme CYP2C9/10 metabolism. Modify Therapy/Monitor Closely.alprazolamMonitor Closely (1)zafirlukast will increase the level or effect of alprazolam by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.amiodaroneMonitor Closely (1)zafirlukast will increase the level or effect of amiodarone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.amitriptylineMinor (1)zafirlukast will increase the level or effect of amitriptyline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.apalutamideMonitor Closely (1)apalutamide will decrease the level or effect of zafirlukast by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor. Coadministration of apalutamide, a weak CYP2C9 inducer, with drugs that are CYP2C9 substrates can result in lower exposure to these medications. Evaluate for loss of therapeutic effect if medication must be coadministered.aprepitantMonitor Closely (1)zafirlukast will increase the level or effect of aprepitant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.aripiprazoleMonitor Closely (1)zafirlukast will increase the level or effect of aripiprazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.armodafinilMinor (1)zafirlukast will increase the level or effect of armodafinil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.artemether/lumefantrineMonitor Closely (1)zafirlukast will increase the level or effect of artemether/lumefantrine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.aspirinMinor (1)aspirin increases levels of zafirlukast by unknown mechanism. Minor/Significance Unknown.aspirin rectalMinor (1)aspirin rectal increases levels of zafirlukast by unknown mechanism. Minor/Significance Unknown.aspirin/citric acid/sodium bicarbonateMinor (1)aspirin/citric acid/sodium bicarbonate increases levels of zafirlukast by unknown mechanism. Minor/Significance Unknown.atazanavirMinor (1)zafirlukast will increase the level or effect of atazanavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.atogepantMonitor Closely (1)zafirlukast will increase the level or effect of atogepant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.atorvastatinMonitor Closely (1)zafirlukast will increase the level or effect of atorvastatin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.avanafilMonitor Closely (1)zafirlukast will increase the level or effect of avanafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inhibitors may reduce avanafil clearance increasing systemic exposure to avanafil; increased levels may result in increased associated adverse events; the maximum recommended dose of STENDRA is 50 mg, not to exceed once every 24 hours for patients taking concomitant moderate CYP3A4 inhibitorsavapritinibMonitor Closely (1)zafirlukast will increase the level or effect of avapritinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.axitinibMonitor Closely (1)zafirlukast increases levels of axitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.bazedoxifene/conjugated estrogensMonitor Closely (1)zafirlukast will increase the level or effect of bazedoxifene/conjugated estrogens by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.bortezomibMonitor Closely (1)zafirlukast will increase the level or effect of bortezomib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.bosentanMinor (2)zafirlukast will increase the level or effect of bosentan by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown. zafirlukast will increase the level or effect of bosentan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.budesonideMonitor Closely (1)zafirlukast will increase the level or effect of budesonide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.buspironeMonitor Closely (1)zafirlukast will increase the level or effect of buspirone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.cannabidiolMonitor Closely (1)cannabidiol will increase the level or effect of zafirlukast by decreasing metabolism. Modify Therapy/Monitor Closely. Cannabidiol may potentially inhibit CYP2C9 activity. Consider reducing the dose when concomitantly using CYP2C9 substrates.carbamazepineMonitor Closely (1)zafirlukast will increase the level or effect of carbamazepine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.carvedilolMonitor Closely (1)zafirlukast will increase the level or effect of carvedilol by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.celecoxibMinor (1)zafirlukast will increase the level or effect of celecoxib by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.cevimelineMinor (1)zafirlukast will increase the level or effect of cevimeline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.cilostazolMonitor Closely (1)zafirlukast will increase the level or effect of cilostazol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.cinacalcetMonitor Closely (1)zafirlukast will increase the level or effect of cinacalcet by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.clarithromycinMinor (1)zafirlukast will increase the level or effect of clarithromycin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.clomipramineMinor (1)zafirlukast will increase the level or effect of clomipramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.clopidogrelMonitor Closely (1)zafirlukast will decrease the level or effect of clopidogrel by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Inhibition of CYP3A4 will reduce clopidogrel bioactivationclozapineMonitor Closely (1)zafirlukast will increase the level or effect of clozapine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.conivaptanMonitor Closely (1)zafirlukast will increase the level or effect of conivaptan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.conjugated estrogensMonitor Closely (1)zafirlukast will increase the level or effect of conjugated estrogens by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.conjugated estrogens, vaginalMonitor Closely (1)zafirlukast will increase the level or effect of conjugated estrogens, vaginal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.cortisoneMonitor Closely (1)zafirlukast will increase the level or effect of cortisone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.dapsoneMinor (1)zafirlukast will increase the level or effect of dapsone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.darifenacinMonitor Closely (1)zafirlukast will increase the level or effect of darifenacin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.darunavirMonitor Closely (1)zafirlukast will increase the level or effect of darunavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.dasatinibMonitor Closely (1)zafirlukast will increase the level or effect of dasatinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.deflazacortMonitor Closely (1)zafirlukast will increase the level or effect of deflazacort by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Decrease deflazacort dose to one-third of the recommended dose if coadministered with moderate or strong CYP3A4 inhibitors.dexamethasoneMonitor Closely (1)zafirlukast will increase the level or effect of dexamethasone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.diazepamMonitor Closely (1)zafirlukast will increase the level or effect of diazepam by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.diclofenacMinor (1)zafirlukast will increase the level or effect of diclofenac by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.dienogest/estradiol valerateMonitor Closely (1)zafirlukast will increase the level or effect of dienogest/estradiol valerate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor for potential adverse effects such as nausea, irregular uterine bleeding, breast tenderness and headache.dihydroergotamineSerious - Use Alternative (1)zafirlukast will increase the level or effect of dihydroergotamine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.dihydroergotamine intranasalSerious - Use Alternative (1)zafirlukast will increase the level or effect of dihydroergotamine intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.disopyramideMinor (1)zafirlukast will increase the level or effect of disopyramide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.docetaxelMinor (1)zafirlukast will increase the level or effect of docetaxel by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.donepezilMinor (1)zafirlukast will increase the level or effect of donepezil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.dronedaroneSerious - Use Alternative (1)zafirlukast will increase the level or effect of dronedarone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.dutasterideMinor (1)zafirlukast will increase the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.efavirenzMinor (1)zafirlukast will increase the level or effect of efavirenz by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.eletriptanMonitor Closely (1)zafirlukast will increase the level or effect of eletriptan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.elvitegravir/cobicistat/emtricitabine/tenofovir DFMonitor Closely (1)elvitegravir/cobicistat/emtricitabine/tenofovir DF decreases levels of zafirlukast by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor. Elvitegravir is a moderate CYP2C9 inducer.eplerenoneMinor (1)zafirlukast will increase the level or effect of eplerenone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.erdafitinibSerious - Use Alternative (1)zafirlukast will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.ergotamineSerious - Use Alternative (1)zafirlukast will increase the level or effect of ergotamine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.erlotinibMonitor Closely (1)zafirlukast will increase the level or effect of erlotinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.erythromycin baseSerious - Use Alternative (1)zafirlukast will increase the level or effect of erythromycin base by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.Minor (1)erythromycin base decreases levels of zafirlukast by inhibition of GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.erythromycin ethylsuccinateSerious - Use Alternative (1)zafirlukast will increase the level or effect of erythromycin ethylsuccinate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.Minor (1)erythromycin ethylsuccinate decreases levels of zafirlukast by inhibition of GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.erythromycin lactobionateSerious - Use Alternative (1)zafirlukast will increase the level or effect of erythromycin lactobionate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.Minor (1)erythromycin lactobionate decreases levels of zafirlukast by inhibition of GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.erythromycin stearateSerious - Use Alternative (1)zafirlukast will increase the level or effect of erythromycin stearate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.Minor (1)erythromycin stearate decreases levels of zafirlukast by inhibition of GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.estradiolMonitor Closely (1)zafirlukast will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.estrogens conjugated syntheticMonitor Closely (1)zafirlukast will increase the level or effect of estrogens conjugated synthetic by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.estrogens esterifiedMonitor Closely (1)zafirlukast will increase the level or effect of estrogens esterified by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.estropipateMonitor Closely (1)zafirlukast will increase the level or effect of estropipate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.ethotoinMonitor Closely (1)zafirlukast will increase the level or effect of ethotoin by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.etonogestrelMonitor Closely (1)zafirlukast will increase the level or effect of etonogestrel by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.etravirineMonitor Closely (2)zafirlukast will increase the level or effect of etravirine by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor. zafirlukast will increase the level or effect of etravirine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.eucalyptusMinor (1)zafirlukast will increase the level or effect of eucalyptus by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.everolimusSerious - Use Alternative (1)zafirlukast will increase the level or effect of everolimus by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.fedratinibSerious - Use Alternative (1)zafirlukast will increase the level or effect of fedratinib by Other (see comment). Avoid or Use Alternate Drug. Avoid coadministration of fedratinib (a CYP3A4 and CYP2C19 substrate) with dual CYP3A4 and CYP2C19 inhibitor. Effect of coadministration of a dual CYP3A4 and CYP2C19 inhibitor with fedratinib has not been studied.felodipineMonitor Closely (1)zafirlukast will increase the level or effect of felodipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.fesoterodineMonitor Closely (1)zafirlukast will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.fezolinetantContraindicated (1)zafirlukast will increase the level or effect of fezolinetant by affecting hepatic enzyme CYP1A2 metabolism. Contraindicated. Fezolinetant AUC and peak plasma concentration are increased if coadministered with drugs that are weak, moderate, or strong CYP1A2 inhibitorsfinasterideMinor (1)zafirlukast will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.finerenoneMonitor Closely (1)zafirlukast will increase the level or effect of finerenone by affecting