Nirvanol is an active metabolite of mephenytoin, a substrate of the cytochrome P450 (CYP) isoform CYP2C19 with anticonvulsant activities.1 It blocks the hind leg tonic extensor phase in a mouse model of seizures induced by maximal electroshock (MES; ED50 = 30 mg/kg).
1.Kupferberg, H.J., and Yonekawa, W.The metabolism of 3-methyl-5-ethyl-5-phenylhydantoin (mephenytoin) to 5-ethyl-5-phenylhydantoin (nirvanol) in mice in relation to anticonvulsant activityDrug Metab. Dispos.3(1)26-29(1975)