pentobarbital will lessen the level or effect of tipranavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.pentobarbital will reduce the extent or effect of roflumilast by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Coadministration not advised; strong cytochrome P450 enzyme inducers lessen