ritlecitinib will raise the level or effect of fentanyl by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Watch Carefully. Ritlecitinib inhibits CYP3A4 substrates; coadministration increases AUC and peak plasma concentration delicate substrates, which may maximize risk of adverse reactions.If coadministration of CYP3A4 inhibi