Watch Carefully (1)phenobarbital will lessen the extent or influence of fentanyl transmucosal by impacting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Watch Intently. Coadministration of fentanyl with CYP3A4 inducers may lead to your lessen in fentanyl plasma concentrations, deficiency of efficacy or, possibly, improvement of a with… Read More