butabarbital will reduce the level or impact of nicardipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.butabarbital will lower the level or influence of cyclosporine by influencing hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Check.butabarbital will lower the level or effect of ritonavir by influencing… Read More