Drug Interaction Report

GENERALLY AVOID: Coadministration with potent CYP450 3A4 or moderate CYP450 2C8 inducers may decrease the plasma concentrations of tucatinib, which is primarily metabolized by CYP450 2C8 and to a lesser extent by CYP450 3A4. When rifampin (600 mg once daily), a potent CYP450 3A4 and moderate CYP450 2C8 inducer, was administered with a single tucatinib dose of 300 mg, tucatinib peak plasma concentration (Cmax) and systemic exposure (AUC) decreased by 40% and 50%, respectively. Reduced efficacy of tucatinib may occur.

MANAGEMENT: Concomitant use of tucatinib with potent CYP450 3A4 or moderate CYP450 2C8 inducers should be avoided.