Decreased C
max & AUC w/ rifabutin, efavirenz, fosamprenavir, phenytoin. Increased plasma conc of terfenadine, astemizole, cisapride, pimozide, halofantrine, quinidine; HMG-CoA reductase inhibitors eg, simvastatin, lovastatin, atorvastatin; vinca alkaloids eg, vincristine, vinblastine; HIV PIs, digoxin. Ergotism w/ ergot alkaloids eg, ergotamine, dihydroergotamine. Elevated ciclosporin levels. Increased C
max & AUC of rifabutin, sirolimus, tacrolimus, midazolam. Frequent ARs & toxicity monitoring w/ Ca-channel blockers eg, diltiazem, verapamil, nifedipine, nisoldipine. Decreased glucose conc w/ sulfonylureas. Increased exposure to tretinoin.