SERIOUS CARDIAC ARRHYTHMIAS INCLUDING VENTRICULAR TACHYCARDIA, VENTRICULAR FIBRILLATION, TORSADES DE POINTES, AND QT PROLONGATION HAVE BEEN REPORTED IN PATIENTS TAKING CISAPRIDE WITH OTHER DRUGS THAT INHIBIT CYTOCHROME P450 3A4, SUCH AS KETOCONAZOLE, ITRACONAZOLE, MICONAZOLE, TROLEANDOMYCIN, ERYTHROMYCIN, FLUCONAZOLE, AND CLARITHROMYCIN. CONCURRENT ADMINISTRATION OF ANTICHOLINERGIC COMPOUNDS WOULD BE EXPECTED TO COMPROMISE THE BENEFICIAL EFFECTS OF CISAPRIDE. THE ACCELERATION OF GASTRIC EMPTYING BY CISAPRIDE COULD AFFECT THE RATE OF ABSORPTION OF OTHER DRUGS. CIMETIDINE COADMINISTRATION LEADS TO AN INCREASED PEAK PLASMA CONCENTRATION AND AUC OF CISAPRIDE. IN PATIENTS RECEIVING ORAL ANTICOAGULANTS, THE COAGULATION TIMES WERE INCREASED IN SOME CASES. THE GASTROINTESTINAL ABSORPTION OF CIMETIDINE AND RANITIDINE IS ACCELERATED WHEN THEY ARE COADMINISTERED WITH CISAPRIDE.