pentobarbital will lessen the extent or influence of parecoxib by impacting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Check.pentobarbital will reduce the extent or effect of tramadol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Keep track of. Decreased AUC of tramadol along with the Lively metabolite (O-desmethyltram