Theophylline, warfarin, carbamazepine, ergot alkaloids, cyclosporin, antacids, cimetidine, methylprednisolone, zidovudine, dideoxyinosine, atorvastatin, oral anticoagulants, efavirenz, fluconazole, indinavir, midazolam, nelfinavir, rifabutin, sildenafil, terfenadine, theophylline, triazolam & trimethoprim/sulfamethoxazole. Increased serum levels w/ digoxin.