Monitor Closely (1)phenobarbital will minimize the level or result of fentanyl transmucosal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Observe Carefully. Coadministration of fentanyl with CYP3A4 inducers could lead into a lessen in fentanyl plasma concentrations, deficiency of efficacy or, perhaps, development of a wit