Possible decreased efficacy w/ antacids, ampicillin, cotrimoxazole, penicillin, rifabutin, rifampin, chloramphenicol, metronidazole, neomycin, nitrofurantoin, sulfonamides, tetracyclines, troleandomycin; carbamazepine, ethosuximide, felbamate, lamotrigine, oxcarbazepine, phenobarb, phenytoin, primidone, topiramate; griseofulvin; clofibrate; boceprevir, telaprevir; ritonavir; nevirapine; barbiturates, benzodiazepines, chloral hydrate, glutethimide, meprobamate; antihistamines, analgesics, antimigraine prep, phenylbutazone prep, vit E. Possible increased plasma conc w/ strong & moderate CYP3A4 inhibitors eg, azole antifungals (eg, ketoconazole, itraconazole, voriconazole, fluconazole), verapamil, macrolides (eg, clarithromycin, erythromycin), diltiazem, grapefruit juice. Possible modified action of alcohol; clonidine; anticoagulants; anticonvulsants; lamotrigine; oral hypoglycemics, insulin; guanethidine, methyldopa; β-blockers; acetaminophen; antipyrine, aspirin; aminocaproic acid; isoproterenol; caffeine; clofibrate; prednisone; cyclosporine; folic acid; meperidine; phenothiazine tranquilizers, reserpine & similar drugs; chlordiazepoxide, diazepam, lorazepam, oxazepam; theophylline; clomipramine (possibly other TCAs); vit B
12. Potential for increased K levels w/ other drugs that can also increase K levels. Reduced effectiveness w/ St. John's wort (
Hypericum perforatum).