Keep an eye on Carefully (one)phenobarbital will minimize the level or result of fentanyl transmucosal by impacting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Intently. Coadministration of fentanyl with CYP3A4 inducers could lead on into a minimize in fentanyl plasma concentrations, lack of efficacy or, probably, developmen