Aromasin

(Exemestane)

Aromasin (Exemestane) is a suicidal aromatase inhibitor. A lot of people get confused by this title so lets break it down. An aromatase inhibitor (AI) is a drug that works by blocking the aromatase enzyme responsible for the production of estrogen. The suicidal component simply means that both its chemical structure and the aromatase enzyme it selects are irreversibly destroyed during the process, in a suicidal manner.

Aromasin was originally developed to fight breast cancer in post-menopausal women, who required a particularly aggressive therapy, and for whom first line defenses like Tamoxifen and Clomiphene Citrate did not work, so its a considerably potent drug. In athletics and bodybuilding, it is used as an ancillary compound within anabolic steroid cycles for its estrogen reducing properties, and has the additional benefit of modestly increasing testosterone levels.

Many anabolic steroids aromatize (convert to estrogen via the aromatase enzyme), a process that is responsible for many of the undesirable side effects which can accompany anabolic steroid use such as acne, gynecomastia, water-retention, etc. Aromasin effectively lowers bodily estrogen production 95-98% by blocking the aromatase enzyme, the one responsible for estrogen synthesis. (1)(2)(3)

As with most of the compounds in this class, it also causes a reasonable rise in testosterone levels (6), and as you may have guessed, this rise in testosterone means that Exemestane can promote androgenic sides (8)(9)(10). The chart below depicts just how efficient it is at both lowering estrogen (estradiol) and raising testosterone.

FIG. 1.
Estrogen and androgen plasma levels after 10 d of daily exemestane (25 or 50 mg) in healthy young males (mean SD; n = 911). To convert to Systeme International units: estradiol, picomoles per liter (x3.671); estrone, picomoles per liter (x3.699); androstenedione, nanomoles per liter (*0.003492); and testosterone, nanomoles per liter (x0.03467).(13)

As depicted in the chart, 25 mg is a very effective dosage, and as an added benefit, Aromasin not only increases testosterone and lowers estrogen, but it also increases Insulin-like Growth Factor (IGF) levels (11). Additionally, it may possibly be less harsh on blood lipids (14) than other AIs used in bodybuilding and athletics. Much like Arimidex, youll need to take it for a week to reach steady blood plasma levels, but unlike Arimidex it has a rather long half-life of 27 hours (12). This combination of characteristics makes it a wise post-cycle therapy addition.

1. A predictive model for exemestane pharmacokinetics/pharmacodynamics incorporating the effect of food and formulation.Br J Clin Pharmacol. 2005 Mar;59(3):355-64.
2. Exemestane for breast cancer prevention: a feasible strategy?Clin Cancer Res. 2005 Jan 15;11(2 Pt 2):918s-24s.
3. Endocrinology and hormone therapy in breast cancer: Aromatase inhibitors versus antioestrogens, Anthony Howell1 and Mitch Dowsett21CRUK Department of Medical Oncology, University of Manchester, Christie Hospital, Manchester, UK2Academic Department of Biochemistry, Royal Marsden Hospital, London, UKBreast Cancer Res 2004, 6:269-274 doi:10.1186/bcr945Published 6 October 2004
4. Eur. J. Cancer. 2000, May;36(8):976-82
5. Breast Cancer Res Treat. 1995;36(3):287-97.
6. J Clin Endocrinol Metab. 2003 Dec;88(12):5951-6.
7. Nippon Yakurigaku Zasshi. 2003 Oct;122(4):345-54.
8. Clin Cancer Res. 2003 Jan;9(1 Pt 2):468S-72S.
9. J Clin Endocrinol Metab 2000 Jul;85(7):2370-7
10. J Steroid Biochem Mol Biol 1997 Nov-Dec;63(4-6):261-7
11. Anticancer Res. 2003 Jul-Aug;23(4):3485-91
12. Clin Cancer Res. 2003 Jan;9(1 Pt 2):468S-72S
13. The Journal of Clinical Endocrinology & Metabolism Vol. 88, No. 12 5951-5956Copyright 2003 by The Endocrine Society
14. J Clin Endocrinol Metab. 2003 Dec;88(12):5951-6.