pentobarbital will lower the extent or effect of etoposide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Watch.pentobarbital will lessen the level or outcome of norgestrel by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Observe Closely. Reasonable CYP3A4 inducers might decrease progestin focus; consi