Isolation and identification of 15-beta-hydroxy cyproterone acetate as a new metabolite of cyproterone acetate in dog, monkey and man.

15-beta-hydroxy cyproterone acetate could be identified by thin layer chromatography, mass spectrum, NMR and IR spectrum as a major unconjugated metabolite of cyproterone acetate in plasma and urine of dog, monkey and man. This metabolite has been found to interferein the Mattingly method for the determination of 11-hydroxy-corticosteroids which suggests, that this method is inadequate in controling the adrenal function of subjects treated with cyproterone acetate.