pentobarbital will reduce the level or outcome of ambrisentan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Slight/Importance Unknown.pentobarbital will lessen the level or impact of norgestrel by influencing hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Watch Carefully. Average CYP3A4 inducers may perhaps lessen progestin