Watch Intently (one)pentobarbital will lessen the extent or impact of mifepristone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Watch. CYP3A4 inducers have not been researched, coadministration not proposed by companypentobarbital will lessen the level or result of efavirenz by affecting hepatic/intestinal enzyme CYP3A4 met