Increased plasma levels w/ strong CYP3A4 inhibitors (eg, ketoconazole, itraconazole, ritonavir, erythromycin, troleandomycin, clarithromycin); cyclosporin. Inhibits metabolism w/ grapefruit or grapefruit juice. Reduced antihypertensive effect w/ CYP3A4 inducers eg, anticonvulsants (eg, phenytoin, phenobarb, carbamazepine) & rifampicin. Potentiated effect w/ alcohol. Increased absorption w/ midazolam. Reduced bioavailability w/ metoprolol. Mean increase in digoxin C
max. May increase bioavailability & hypotensive effect w/ higher dose of cimetidine. Increased hypotensive effects w/ other medications affecting BP eg, α-blockers, TCAs, neuroleptics. Reduced hypotensive effect w/ corticosteroids. Terfenadine, astemizole, class III anti-arrhythmics (eg, amiodarone, quinidine, sotalol).