Drug Interaction Report

MONITOR: Coadministration with inducers of CYP450 3A4 may decrease the plasma concentrations of ixabepilone, which is primarily metabolized by the isoenzyme. According to the manufacturer, coadministration of ixabepilone with the potent CYP450 3A4 inducer rifampin decreased ixabepilone systemic exposure (AUC) by 43% compared to administration of ixabepilone alone. Reduced efficacy of ixabepilone may occur. However, the extent to which less potent CYP450 3A4 inducers interact with ixabepilone is unknown.

MANAGEMENT: The potential for diminished pharmacologic effects of ixabepilone should be considered during coadministration with CYP450 3A4 inducers. Caution is advised if they are used with ixabepilone, and alternative treatments may be required if an interaction is suspected.

GENERALLY AVOID: Grapefruit juice may increase the plasma concentrations of ixabepilone. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruits.

MANAGEMENT: Patients treated with ixabepilone should avoid the consumption of grapefruit or grapefruit juice.