Inhibited absorption w/ antacids, H
2 antagonists. Reduced therapeutic effects w/ sucralfate. Decreased bioavailability w/ PPI, INH. Decreased serum levels w/ rifampicin. Decreased theophylline serum levels. Increased plasma levels of cyclosporine, tacrolimus, methylprednisolone, midazolam, triazolam, digoxin, hypoglycemics, indinavir, ritonavir, saquinavir, TCAs, carbamazepine, quinidine, sulfonylureas, buspirone, HMG-CoA reductase inhibitors, nisoldipine, zolpidem, warfarin, corticosteroids & drugs metabolized by cytochrome P450 3A4 enzymes. Inhibited metabolism of terfenadine, astemizole & cisapride.