pentobarbital will lower the extent or outcome of verapamil by influencing hepatic/intestinal enzyme CYP3A4 metabolism. Use Warning/Monitor.pentobarbital will reduce the level or effect of fentanyl transdermal by impacting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Keep an eye on Closely. Coadministration of fentanyl with CYP3A4 in