Identification of the fecal metabolites of 17-alpha-methyltestosterone in the dog.

17alpha-Methyltestosterone-4-(14)C was fed to two dogs in an experiment to determine tissue localization and metabolic disposition of this hypocholesterolemic steroid. No accumulation of the drug was found in any tissue, although a small amount of radioactivity was detected in the liver and the ileal mucosa of one animal. Most of the administered radio-activity was excreted in urine and feces. The urinary metabolites consisted largely of highly polar compounds which appeared resistant to glucuronidase treatment or solvolysis procedures. Analysis of the fecal metabolites showed the presence of unchanged methyltestosterone, of four isomeric methylandrostanediols, and of labeled unidentified polar compounds. Of the four identified methylandrostane-diols, the predominating fecal diols were 17alpha-methyl-5alpha-androstane-3beta,17beta-diol (45-62%) and 17alpha-methyl-5-androstane-3alpha,17-diol (12-28%); 17alpha-methyl-5alpha-androstane-3alpha,-17-diol and the 5beta:3beta isomer were found in very small amounts only.