Butabarbital will lower the level or effect of levonorgestrel oral/ethinylestradiol/ferrous bisglycinate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Check Intently. The efficacy of hormonal contraceptives might be lowered. butabarbital will minimize the level or outcome of estrogens esterified by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use W... https://eugeneo094mqp4.wikicorrespondent.com/user