pentobarbital will minimize the extent or effect of tipranavir by influencing hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Watch.pentobarbital will lessen the extent or impact of fentanyl transmucosal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Keep an eye on Carefully. Coadministration of fentanyl with CYP3