Enhanced antihypertensive effect w/ other antihypertensives & TCAs. Increased plasma levels w/ cimetidine, azole antifungals (eg, itraconazole, ketoconazole), macrolides (eg, erythromycin), telithromycin or HIV-PIs. Increased C
max & AUC w/ grapefruit juice. Reduced plasma levels w/ carbamazepine, phenytoin, barbiturates (eg, phenobarb) & rifampicin. Enhanced preexisting hypokalemia w/ diuretics & antihypertensive effect w/ hydrochlorothiazide. Increased C
max of cyclosporine & blood levels of digoxin.