pentobarbital will lessen the extent or result of etravirine by impacting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Watch.pentobarbital decreases amounts of elvitegravir/cobicistat/emtricitabine/tenofovir DF by influencing hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. May possibly produce loss of virologic response an