Plasmakoncentrationen for phenytoin, phenobarbital og andre antikonvulsiva, som er substrater for CYP450 - isoenzymer, kan eventuelt falde eller stige, når disse administreres samtidigt med efavirenz.
There is a potential for reduction or increase in the plasma concentrations of phenytoin, phenobarbital and other anticonvulsants that are substrates of CYP450 isoenzymes when co- administered with efavirenz.