butabarbital will lower the extent or impact of doravirine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.butabarbital will lessen the extent or effect of fosphenytoin by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Keep track of.Butabarbital belongs to the group of medicines termed barbiturates. They act wh