ritlecitinib will boost the level or effect of fentanyl by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Watch Intently. Ritlecitinib inhibits CYP3A4 substrates; coadministration will increase AUC and peak plasma concentration delicate substrates, which can improve risk of adverse reactions.Observe Closely (two)efavirenz wil