METABOLISM OF 4-C14-TESTOSTERONE IN HUMAN SUBJECTS. I. DISTRIBUTION IN BILE, BLOOD, FECES AND URINE

Abstract

4-C14-Testos-terone has been administered intravenously to 20 human subjects. The radioactivity was excreted almost quantitatively in the urine in 48 hours with over 50% in the first 4 hours. About 50% of the radioactivity could be extracted from urine following different hydrolytic procedures. C14 Testosterone was cleared from the plasma rapidly with at least 2 separate rates. These 2 pools had half-lives of 11 and 100 minutes. Conjugated metabolites of Cl4-testosterone reached their peak in the plasma within 15 minutes following injection of the steroid. From 12 to 14% of the injected radioactivity was excreted in the bile of subjects with T-tube drainage and only 6% in the stools of patients having no T-tube, which probably indicates reabsorption of steroids from the gastrointestinal tract. The metabolites in bile were in conjugated form, whereas a great part of the radioactivity in the stools was in free form.