butabarbital will lower the level or effect of nifedipine by influencing hepatic/intestinal enzyme CYP3A4 metabolism. Minimal/Significance Not known.butabarbital will reduce the level or result of glecaprevir/pibrentasvir by impacting hepatic/intestinal enzyme CYP3A4 metabolism.Teniposide: Barbiturates may perhaps reduce the serum concentration of