Terfenadine, astemizole and cisapride are all metabolized by the cytochrome P450IIIA4 isozyme, and it has been demonstrated that ketoconazole, a potent inhibitor of IIIA4, blocks the metabolism of these drugs, resulting in increased plasma concentrations of parent drug.
<Terfenadine, mechanism, ketoconazole>, <astemizole, mechanism, ketoconazole>, <cisapride, mechanism, ketoconazole>