Excretion of the metabolites of testosterone-4-C14 in the rat.

In most of the experiments previously reported on the metabolism of testosterone, reviewed by Dorfman (l), rather large quantities of this steroid have been administered to experimental subjects and the urine collected for the estimation of androgenic compounds. In general, metabolites amounting to about 20 per cent of the administered compound have been found in the urine of animals. However, in t,he important studies of Dobriner and Lieberman (2) in which 90 mg. of testosterone per day were administered to a man for 45 days, metabolites equivalent to 50 per cent of this steroid were recovered from the urine. Failure to find all of the injected testosterone as recognizable metabolites might have one of two explanations, or might include a combination of both. Either the steroid is degraded to non-steroidal, hence not easily recognizable, metabolites, or else only a portion of the metabolites of the injected material is eliminated via the urine. That other pathways of excretion are important was demonstrated by the experiments of Paschkis et al. (3) in which significant amounts of androgenic material were found in the bile of dogs after injection of testosterone, androsterone, or methyltestosterone. However, Dorfman (1) reported that oral administration of large quantities of testosterone propionate to a woman with a bile fistula did not result in excretion of androgens or 17ketosteroids in bile. Since the initiation of the work reported in this paper, Gallagher et al. (4) have reported some studies on the metabolism of radioactive testosterone in rats and mice. After intraperitoneal administration of testosterone4-V dissolved in aqueous propylene glycol no Cl*02 was found in the expired air of mice during the succeeding 3 days. The distribution of radioactivity in the excreta of rats 24 hours after injection showed 7 to 12 per cent of the administered radioactivity in the urine, 31 to 40 per cent in the