Abstract
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.
MeSH terms
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Antihypertensive Agents / adverse effects*
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Antihypertensive Agents / therapeutic use
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Cisapride
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Cytochrome P-450 CYP3A
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Cytochrome P-450 Enzyme Inhibitors
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Diltiazem / adverse effects*
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Diltiazem / therapeutic use
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Drug Interactions
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Enzyme Inhibitors / adverse effects
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Female
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Gastroesophageal Reflux / drug therapy
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Gastrointestinal Agents / adverse effects*
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Gastrointestinal Agents / therapeutic use
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Heart Rate / drug effects
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Humans
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Long QT Syndrome / chemically induced*
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Middle Aged
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Mixed Function Oxygenases / antagonists & inhibitors
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Piperidines / adverse effects*
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Piperidines / blood
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Piperidines / therapeutic use
Substances
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Antihypertensive Agents
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Cytochrome P-450 Enzyme Inhibitors
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Enzyme Inhibitors
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Gastrointestinal Agents
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Piperidines
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Mixed Function Oxygenases
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CYP3A protein, human
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Cytochrome P-450 CYP3A
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CYP3A4 protein, human
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Diltiazem
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Cisapride