Drug Interaction Report

MONITOR: Coadministration with inducers of CYP450 3A4 may decrease the plasma concentrations of idelalisib, which is a substrate of the isoenzyme. In healthy volunteers, administration of a single 150 mg dose of idelalisib with the potent CYP450 3A4 inducer rifampin (600 mg daily for 8 days) decreased mean idelalisib peak plasma concentration (Cmax) by 58% and systemic exposure (AUC) by 75%. Data are not available for idelalisib in combination with other, less potent CYP450 3A4 inducers.

MANAGEMENT: Patients receiving idelalisib with CYP450 3A4 inducers should be monitored for potentially diminished pharmacologic response to idelalisib. Concomitant use should be avoided if an interaction is suspected.