Pharmacokinetics and pharmacodynamics of testosterone enanthate and dihydrotestosterone enanthate in non-human primates
- 1 April 1990
- journal article
- research article
- Published by Oxford University Press (OUP) in Acta Endocrinologica
- Vol. 122 (4), 432-442
- https://doi.org/10.1530/acta.0.1220432
Abstract
The pharmacokinetics and pharmacodynamics of testosterone enanthate and dihydrotestosterone-enanthate were compared in orchidectomized cynomolgus monkeys (Macaca fascicularis) and in intact GnRH agonist-suppressed rhesus monkeys (Macaca mulatta). Following a single im injection of 32.8 mg testosterone enanthate or 32.7 mg dihydrotesteosterone- enanthate, i.e. 23.6 mg of pure steroid, in the orchidectomized cynomolgus monkeys, serum testerone and dihydrotestosterone levels rose to 400 and 800% of baseline,respectively, wtihin 24 h. Androgen levels remained in the range for 3-5 days followed by a continuous decline until baseline values were attained after 4-5 weeks. The areas under the testosterone- and dihydrotestosterone-curves did not differ significantly 2290 .+-. 340 (dihydrotestosterone-enanthate) vs 2920 .+-. 485 (testosterone-enanthate) suggesting that similar amounts of steroid had been released from the repective ester preparation. Mean half-life estimates of the terminal elimination phase were 4 and 7 days for testosterone-enanthate and dihydrotesterone-enanthate, respectively. In a second experiment rhesus monkeys received, at 4-weekly intervals, sc implantation of a biodegradable polylactic: polyglycolide rod loaded with the GnRH angonist buserelin. The last injection was given during week 20. GnRH agonist treatment suppressed serum bioactive LH, testosterone and dihydrotestosterone levels, testicular size, sperm production, and seminal carnitine content. The ejaculatory response to electrostimulation and the masturbatory behaviour were abolished. Testosterone or dihydrotestosterone injections at the same doses as above were given in week 10, 14, 17 and 20 of GnRH agonist treatment. Serum testosterone and dihydrotestosterone levels were stimulated 9- and 4-fold, respectively. Mean half-life estimates for testosterone-enanthate and dihydrotestosterone were 5 and 7 days, respectively. Both ester preparations completely restored the ejaculatory response, ejaculate size, masturbatory behaviour, and seminal carnithine levels. In conclusion, androgen substitution with dihydrotestosterone-enanthate, in equivalent doses, is an effective as testosterone-enanthate in restoring reproductive functions in hypogonadal monkeys.This publication has 21 references indexed in Scilit:
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