Investigation of the stereoselective in vitro biotransformation of glutethimide by high-performance liquid chromatography and capillary electrophoresis.

Due to our interest in drugs with a glutarimide structure, we reinvestigated the stereoselectivity of the in vitro biotransformation of the chiral hypnotic-sedative drug glutethimide. Glutethimide enantiomers were separated on a preparative scale by HPLC on cellulose tris(4-methylbenzoate) as chiral stationary phase. The enantiomeric purity was higher than 99%. A reversed-phase HPLC method was developed to determine the metabolites of glutethimide. After incubations with rat liver microsomes both enantiomers formed 5-hydroxyglutethimide as the main metabolite, as well as additional metabolites, of which some were formed stereoselectively. Mass spectrometry of the unknown metabolites indicated a hydroxylation in the ethyl side chain for two of the metabolites. A third metabolite was tentatively identified as desethylglutethimide.