Decreased C
max & AUC by rifabutin, phenytoin, cimetidine, efavirenz, fosamprenavir. Increased plasma conc of terfenadine, astemizole, cisapride, pimozide, quinidine, vinca alkaloids (eg, vincristine & vinblastine), digoxin, HIV PIs. Ergotism w/ ergot alkaloids eg, ergotamine, dihydroergotamine. Elevated cyclosporine levels. Increased C
max & AUC of tacrolimus, sirolimus, rifabutin, midazolam, simvastatin, HIV PIs (eg, atazanavir). Decreased glucose conc w/ sulfonylureas.