Interactions between efavirenz and Cisapride (cisapride)
cisapride and efavirenz (Major Drug-Drug)
CONTRAINDICATED: Based on in vitro data, coadministration with the non-nucleoside reverse transcriptase inhibitors (NNRTIs), delavirdine and efavirenz, may increase the plasma concentrations of cisapride. The mechanism is NNRTI inhibition (both competitive and non-competitive) of CYP450 3A4, the isoenzyme responsible for the metabolic clearance of cisapride. Although the interaction has not been specifically studied with either NNRTI, high plasma levels of cisapride have been associated with prolongation of the QT interval on the ECG; ventricular arrhythmias including ventricular tachycardia, ventricular fibrillation, and torsade de pointes; cardiac arrest; and sudden death.
MANAGEMENT: Given the potential for serious and life-threatening adverse cardiac events associated with increased plasma levels of cisapride, the concomitant use with delavirdine or efavirenz is considered contraindicated.
