pentobarbital will decrease the extent or impact of cyclosporine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Warning/Observe.pentobarbital will decrease the extent or outcome of fentanyl transdermal by impacting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Keep an eye on Closely. Coadministration of fentanyl with CY