Studies related to the metabolism of anabolic steroids in the horse: the identification of some 16-oxygenated metabolites of testosterone and a study of the phase II metabolism.

1. Isomers of 3,17-dihydroxyandrostan-16-one, 3,16-dihydroxyandrostan-17-one and androstane-3,16,17-triol have been identified as urinary metabolites of testosterone in the horse. 2. Following XAD-2 extraction of urine samples, Sephadex LH-20 chromatography was used to separate the extract into conjugate groups. Metabolites obtained after hydrolysis of the conjugates have been investigated by g.l.c.-mass spectrometry. 3. Testosterone, 3,17-dihydroxyandrostan-16-one and 3,16-dihydroxyandrostan-17-one were found only in the sulphate fraction. 5 alpha-Androstane-3 beta,17 beta-diol, and two isomeric androstane triols were present mainly in this fraction and 5 alpha-androstane-3 beta,17 alpha-diol was a minor component. In the glucuronide fraction 5 alpha-androstane-3 beta,17 alpha-diol was the major metabolite present and 5 alpha-androstane-3 beta,17 beta-diol and the two isomeric triols were minor components.