ritlecitinib will raise the level or effect of fentanyl by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Keep track of Carefully. Ritlecitinib inhibits CYP3A4 substrates; coadministration will increase AUC and peak plasma concentration delicate substrates, which can maximize risk of adverse reactions.Watch Intently (2)efavir