pentobarbital will minimize the extent or result of doxorubicin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Warning/Watch.pentobarbital will lessen the level or result of tramadol by influencing hepatic/intestinal enzyme CYP3A4 metabolism. Use Warning/Watch. Lowered AUC of tramadol as well as active metabolite (O-desmethyltramadol