Check Intently (1)pentobarbital will lower the level or effect of fentanyl transmucosal by impacting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Watch Intently. Coadministration of fentanyl with CYP3A4 inducers could lead into a lower in fentanyl plasma concentrations, insufficient efficacy or, maybe, enhancement of a withdrawal syn