Drug Interaction Report

MONITOR: Coadministration with CYP450 3A4 inducers may decrease the plasma concentration and pharmacologic effects of ritlecitinib. The proposed mechanism is increased clearance of ritlecitinib due to induction of the CYP450 3A4 isoenzyme, one of the pathways of elimination of ritlecitinib. When a single 50 mg dose of ritlecitinib was administered in combination with the potent CYP450 3A4 inducer rifampin (600 mg once daily for 8 days), the mean peak plasma concentration (Cmax) and systemic exposure (AUC) of ritlecitinib decreased by approximately 25% and 44%, respectively, compared to ritlecitinib administered alone. Data are not available of other, less potent inducers.

MANAGEMENT: Caution is advised when ritlecitinib is used with CYP450 3A4 inducers. The possibility of diminished therapeutic effects should be considered.