STUDIES ON THE METABOLISM OF TESTOSTERONE TRANS-4-N-BUTYLCYCLOHEXANOIC ACID IN THE CYNOMOLGUS MONKEY, MACACA-FASCICULARIS

Metabolism of intravenously administered testosterone trans-4-n-butylc yclohexanoate (T bucyclate), a potent, long-acting androgen, was studi ed in cynomolgus monkeys (Macaca fascicularis). About 5% of the radioa ctivity of a dose of doubly labeled ester (C-14, H-3) was excreted via the gastrointestinal tract. Most of the administered radioactivity wa s excreted in the urine within 120 h. No intact T bucyclate was recove red from either compartment. Tritium attributed to bucyclic acid and i ts metabolites was excreted rapidly (peak excretion was at 6 h after i njection), while C-14 excretion, attributed to testosterone and its me tabolites, extended over 4 days. Testosterone metabolites were excrete d predominantly as sulfate esters. Analysis of urinary products derive d from the bucyclic acid moiety of T bucyclate showed no products susc eptible to glucuronidase treatment, and showed a mixture of unidentifi ed solvolyzable and unconjugated products. No unmetabolized trans-4-n- butylcyclohexanoic acid was detected in urine or feces. It is conclude d that metabolism of testosterone bucyclate is initiated in vivo in cy nomolgus monkeys by hydrolysis of ester to testosterone and bucyclic a cid. The bucyclate side chain is rapidly cleared, and the testosterone is retained in the circulation.