<p>Concurrent admin with enzyme-inducing drugs (e.g. rifampicin, phenobarbital, carbamazepine) reduced plasma concentrations of isradipine. Increased bioavailability with cimetidine. May increase serum levels with CYP3A4 inhibitors (e.g. macrolides, HIV protease inhibitors, azole antifungals, delavirdine).</p>