butabarbital will lower the level or result of sulfamethoxazole by impacting hepatic enzyme CYP2C9/10 metabolism. Slight/Significance Unfamiliar.butabarbital will lessen the extent or impact of estrogens esterified by impacting hepatic/intestinal enzyme CYP3A4 metabolism. Use Warning/Watch.Teniposide: Barbiturates may possibly decrease the serum fo