Key result
Concomitant administration of cisapride and diltiazem resulted in near syncope and QT-interval prolongation, which resolved upon discontinuation of cisapride.
Why the study?
Does concomitant administration of cisapride and diltiazem cause QT-interval prolongation?
Case Report (n=1)
Does concomitant administration of cisapride and diltiazem cause QT-interval prolongation?
Concomitant use of cisapride and diltiazem may lead to clinically significant QT prolongation due to CYP3A4 inhibition.
May warrant QT monitoring with CYP3A4 inhibitors; leaves open confirmation of interaction frequency in prospective studies.
Cisapride, a cytochrome P450 3A4 (CYP3A4) substrate, is widely prescribed for the treatment of gastrointestinal motility disorders. Prolongation of QT interval, torsades de pointes, and sudden cardiac death have been reported after concomitant administration with erythromycin or azole antifungal agents, but not with other CYP3A4 inhibitors. A possible drug interaction occurred in a 45-year-old woman who was taking cisapride for gastroesophageal reflux disorder and diltiazem, an agent that has inhibitory effect on CYP3A4, for hypertension. The patient was in near syncope and had QT-interval prolongation. After discontinuing cisapride, the QT interval returned to normal and symptoms did not recur. We suggest that caution be taken when cisapride is prescribed with any potent inhibitor of CYP3A4, including diltiazem.
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Thomas et al. (1998) conducted a case report in Gastroesophageal reflux disorder and hypertension (n=1). Concomitant administration of cisapride and diltiazem was evaluated on QT-interval prolongation and near syncope. Concomitant administration of cisapride and diltiazem resulted in near syncope and QT-interval prolongation, which resolved upon discontinuation of cisapride.
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