pentobarbital will reduce the level or impact of etoposide by influencing hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Keep track of.pentobarbital will lessen the extent or impact of tramadol by influencing hepatic/intestinal enzyme CYP3A4 metabolism. Use Warning/Monitor. Diminished AUC of tramadol along with the active metabolite (O-de