Butabarbital will lower the level or effect of levonorgestrel oral/ethinylestradiol/ferrous bisglycinate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. The efficacy of hormonal contraceptives might be diminished. butabarbital will lower the extent or impact of glecaprevir/pibrentasvir by impacting hepatic/intestinal enzyme CYP3A4 metabolism. ... https://ferdinandy310ysq3.wikifrontier.com/user