pentobarbital will reduce the extent or effect of etonogestrel by influencing hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Observe.pentobarbital will reduce the extent or result of tamoxifen by influencing hepatic/intestinal enzyme CYP3A4 metabolism. Use Warning/Check.pentobarbital will decrease the level or result of ixabepilone by imp