of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of crizotinib with CYP3A substrates with narrow therapeutic indices should be avoided.crofelemerMonitor Closely (1)crofelemer increases levels of theophylline 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.cyclophosphamideMinor (1)cyclophosphamide will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.dabrafenibMonitor Closely (1)dabrafenib will decrease the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.daridorexantMonitor Closely (1)theophylline and daridorexant both increase sedation. Modify Therapy/Monitor Closely. Coadministration increases risk of CNS depression, which can lead to additive impairment of psychomotor performance and cause daytime impairment. darifenacinMonitor Closely (1)darifenacin will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.darunavirMonitor Closely (1)darunavir will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.dasatinibMonitor Closely (1)dasatinib will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.deferasiroxMonitor Closely (1)deferasirox will increase the level or effect of theophylline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor. Avoid the concomitant use of theophylline with deferasirox. If you must co-administer theophylline and deferasirox, monitor theophylline concentration and consider theophylline dose modification.deflazacortMonitor Closely (1)theophylline and deflazacort both decrease serum potassium. Use Caution/Monitor.dexamethasoneMonitor Closely (1)dexamethasone will decrease the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.dexlansoprazoleMinor (1)dexlansoprazole increases toxicity of theophylline by Other (see comment). Minor/Significance Unknown. Comment: Prolonged use of proton pump inhibitors can cause hypochlorhydria, which in turn causes peristalsis in small intestine to increase and peristalsis in the proximal colon to decrease; monitor for toxicity.DHEA, herbalMonitor Closely (1)DHEA, herbal will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.dichlorphenamideMonitor Closely (2)dichlorphenamide and theophylline both decrease serum potassium. Use Caution/Monitor. dichlorphenamide, theophylline. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Both drugs can cause metabolic acidosis.difelikefalinMonitor Closely (1)difelikefalin and theophylline both increase sedation. Use Caution/Monitor.diltiazemMonitor Closely (1)diltiazem will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.dipyridamoleContraindicated (1)theophylline decreases effects of dipyridamole by pharmacodynamic antagonism. Contraindicated. May produce false negative results in dipyridamole thallium imaging tests. Separate by 24 hr.disulfiramMinor (1)disulfiram increases levels of theophylline by decreasing metabolism. Minor/Significance Unknown.doxapramMonitor Closely (1)doxapram, theophylline. Mechanism: unspecified interaction mechanism. Use Caution/Monitor. Increased skeletal muscle activity, agitation, hyperactivity.dronedaroneMonitor Closely (1)dronedarone will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.dulaglutideMonitor Closely (1)dulaglutide, theophylline. Other (see comment). Use Caution/Monitor. Comment: Dulaglutide slows gastric emptying and may impact absorption of concomitantly administered oral medications; be particularly cautious when coadministered with drugs that have a narrow therapeutic index.dupilumabMonitor Closely (1)dupilumab, theophylline. Other (see comment). Use Caution/Monitor. Comment: Formation of CYP450 enzymes can be altered by increased levels of certain cytokines during chronic inflammation; thus, dupilumab could normalize the formation of CYP450 enzymes. Upon initiation or discontinuation of dupilumab in patients who are receiving concomitant CYP450 substrates, particularly those with a narrow therapeutic index, consider monitoring for therapeutic effect.efavirenzMonitor Closely (1)efavirenz will decrease the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.elagolixMonitor Closely (1)elagolix decreases levels of theophylline 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.elderberryMinor (1)elderberry increases effects of theophylline by decreasing metabolism. Minor/Significance Unknown.elvitegravir/cobicistat/emtricitabine/tenofovir DFMonitor Closely (1)elvitegravir/cobicistat/emtricitabine/tenofovir DF increases levels of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Cobicistat is a CYP3A4 inhibitor; contraindicated with CYP3A4 substrates for which elevated plasma concentrations are associated with serious and/or life-threatening events.encorafenibMonitor Closely (1)encorafenib, theophylline. 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.epcoritamabMonitor Closely (1)epcoritamab, theophylline. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Epcoritamab causes release of cytokines that may suppress activity of CYP enzymes, resulting in increased exposure of CYP substrates. For certain CYP substrates, minimal changes in their concentration may lead to serious adverse reactions. If needed, modify therapy as recommended in the substrate's prescribing information. .erythromycin baseMonitor Closely (1)erythromycin base will increase the level or effect of theophylline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)erythromycin base will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.erythromycin ethylsuccinateMonitor Closely (1)erythromycin ethylsuccinate will increase the level or effect of theophylline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)erythromycin ethylsuccinate will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.erythromycin lactobionateMonitor Closely (1)erythromycin lactobionate will increase the level or effect of theophylline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)erythromycin lactobionate will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.erythromycin stearateMonitor Closely (1)erythromycin stearate will increase the level or effect of theophylline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)erythromycin stearate will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.eslicarbazepine acetateMonitor Closely (1)eslicarbazepine acetate will decrease the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.esmololMonitor Closely (1)esmolol, theophylline. Other (see comment). Use Caution/Monitor. Comment: Beta blockers (esp. non selective) antagonize theophylline effects, while at the same time increasing theophylline levels and toxicity (mechanism: decreased theophylline metabolism). Smoking increases risk of interaction.esomeprazoleMinor (1)esomeprazole increases toxicity of theophylline by Other (see comment). Minor/Significance Unknown. Comment: Prolonged use of proton pump inhibitors can cause hypochlorhydria, which in turn causes peristalsis in small intestine to increase and peristalsis in the proximal colon to decrease; monitor for toxicity.ethinylestradiolMonitor Closely (1)ethinylestradiol will increase the level or effect of theophylline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.etravirineMonitor Closely (1)etravirine will decrease the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.febuxostatContraindicated (1)febuxostat increases levels of theophylline by decreasing metabolism. Contraindicated.fedratinibMonitor Closely (1)fedratinib will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP3A4 substrates as necessary.ferric maltolMonitor Closely (1)ferric maltol, theophylline. Either increases levels of the other by unspecified interaction mechanism. Modify Therapy/Monitor Closely. Coadministration of ferric maltol with certain oral medications may decrease the bioavailability of either ferric maltol and some oral drugs. For oral drugs where reductions in bioavailability may cause clinically significant effects on its safety or efficacy, separate administration of ferric maltol from these drugs. Duration of separation may depend on the absorption of the medication concomitantly administered (eg, time to peak concentration, whether the drug is an immediate or extended release product).fexinidazoleMonitor Closely (1)fexinidazole will increase the level or effect of theophylline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)fexinidazole will increase the level or effect of theophylline 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.fezolinetantContraindicated (1)theophylline 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 inhibitorsfluconazoleMonitor Closely (1)fluconazole will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.fludrocortisoneMonitor Closely (1)fludrocortisone will decrease the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.fluvoxamineSerious - Use Alternative (1)fluvoxamine will increase the level or effect of theophylline by affecting hepatic enzyme CYP1A2 metabolism. Avoid or Use Alternate Drug.fosamprenavirMonitor Closely (1)fosamprenavir will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.fosaprepitantMonitor Closely (1)fosaprepitant will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.fosphenytoinMonitor Closely (1)fosphenytoin will decrease the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.givosiranSerious - Use Alternative (1)givosiran will increase the level or effect of theophylline by affecting hepatic enzyme CYP1A2 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sensitive CYP1A2 substrates with givosiran. If unavoidable, decrease the CYP1A2 substrate dosage in accordance with approved product labeling.glofitamabMonitor Closely (1)glofitamab, theophylline. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Glofitamab causes release of cytokines that may suppress activity of CYP enzymes, resulting in increased exposure of CYP substrates. For certain CYP substrates, minimal changes in their concentration may lead to serious adverse reactions. If needed, modify therapy as recommended in the substrate's prescribing information. .grapefruitMonitor Closely (1)grapefruit will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.green teaMonitor Closely (1)green tea increases levels of theophylline by decreasing renal clearance. Use Caution/Monitor. Due to caffeine content.griseofulvinMonitor Closely (1)griseofulvin will decrease the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.guselkumabMonitor Closely (1)guselkumab, theophylline. Other (see comment). Use Caution/Monitor. Comment: Formation of CYP450 enzymes can be altered by increased levels of certain cytokines during chronic inflammation; thus, normalizing the formation of CYP450 enzymes. Upon initiation or discontinuation of guselkumab in patients who are receiving concomitant CYP450 substrates, particularly those with a narrow therapeutic index, consider monitoring for therapeutic effect.hydrocortisoneMonitor Closely (1)hydrocortisone will decrease the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.idelalisibSerious - Use Alternative (1)idelalisib will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Idelalisib is a strong CYP3A inhibitor; avoid coadministration with sensitive CYP3A substratesiloperidoneMonitor Closely (1)iloperidone increases levels of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Iloperidone is a time-dependent CYP3A inhibitor and may lead to increased plasma levels of drugs predominantly eliminated by CYP3A4.indacaterol, inhaledMonitor Closely (1)theophylline, indacaterol, inhaled. serum potassium. Use Caution/Monitor. Combination may increase risk of hypokalemia.indinavirMonitor Closely (1)indinavir will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.interferon alfa 2bMonitor Closely (1)interferon alfa 2b increases levels of theophylline by decreasing metabolism. Use Caution/Monitor. Greater risk of interaction in smokers.interferon alfa n3Monitor Closely (1)interferon alfa n3 increases levels of theophylline by decreasing metabolism. Use Caution/Monitor. Greater risk of interaction in smokers.interferon gamma 1bMonitor Closely (1)interferon gamma 1b increases levels of theophylline by decreasing metabolism. Use Caution/Monitor. Greater risk of interaction in smokers.iodine (radioactive)Monitor Closely (1)iodine (radioactive) increases levels of theophylline by decreasing elimination. Use Caution/Monitor.isoniazidMonitor Closely (2)isoniazid will increase the level or effect of theophylline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor. isoniazid will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.istradefyllineMonitor Closely (1)istradefylline will increase the level or effect of theophylline 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.itraconazoleMonitor Closely (1)itraconazole will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.ivosidenibSerious - Use Alternative (1)ivosidenib will decrease the level or effect of theophylline 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.ixekizumabMonitor Closely (1)ixekizumab, theophylline. Other (see comment). Use Caution/Monitor. Comment: Formation of CYP450 enzymes can be altered by increased levels of certain cytokines during chronic inflammation; thus, ixekizumab could normalize the formation of CYP450 enzymes. Upon initiation or discontinuation of ixekizumab in patients who are receiving concomitant CYP450 substrates, particularly those with a narrow therapeutic index, consider monitoring for therapeutic effect.ketoconazoleSerious - Use Alternative (1)ketoconazole will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.labetalolMonitor Closely (1)labetalol, theophylline. Other (see comment). Use Caution/Monitor. Comment: Beta blockers (esp. non selective) antagonize theophylline effects, while at the same time increasing theophylline levels and toxicity (mechanism: decreased theophylline metabolism). Smoking increases risk of interaction.lansoprazoleMinor (2)lansoprazole increases levels of theophylline by decreasing metabolism. Minor/Significance