Exemestane, the active ingredient in Pfizer’s Aromasin [structural formula shown below], truly is a body recompositioning drug. At least it is if you’re prepared to accept the results of an Italian study in which 33 women used exemestane for a period of 2 years.
Exemestane is an aromatase inhibitor with a steroid skeleton. Apart from the ethyl group on C6, the compound bears a striking resemblance to boldenone. If the enzyme aromatase – which converts androstenedione and testosterone into estradiol – tries to provide exemestane with an aromatic ring, it gets so stuck that it breaks down. This is how exemestane lowers oestrogen levels.
Once women with an estradiol-sensitive form of cancer have undergone chemotherapy, an operation and radiation therapy, they usually take anti-oestrogens for five years after that. Most take nolvadex for a couple of years and then go over to an anti-oestrogen like anastrazole or exemestane. Little is known about the long-term effects of exemestane, hence the Italian research.
The researchers monitored 68 older women for 2 years. All the women had already been taking 20 mg nolvadex daily for 2-3 years. Half of them continued with this and the other half started taking 25 mg exemestane per day instead.
The exemestane group built up lean body mass. In the two years that the trial lasted the women in that group gained an average of 2.2 kg lean body mass. And the same group lost an average of 0.7 kg fat. The figures below show the effects as a percentage.
The triglyceride levels in the blood of the women in the exemestane group went down – a positive development. At the same time exemestane increased the levels of LDL [bad cholesterol] and reduced the concentration of HDL [good cholesterol] – a negative development.
American cancer researchers have offered an explanation of how exemestane might cause these effects. Exemestane itself has almost no androgenic effect, but the researchers announced in 2007 that an exemestane metabolite – the 17beta-hydroxy analogue – is capable of interacting with the androgen receptor. [Mol Cancer Ther. 2007 Nov;6(11):2817-27.]
This means that women should consider carefully whether to use exemestane or not. It also means that exemestane is now of interest to chemical athletes with modest aims.
If men take 25 mg exemestane daily their testosterone level rises by a third, researchers at Farmitalia discovered in the 1980s. [J Steroid Biochem. 1988; 30(1-6): 391-4.] A dose of 50 mg does the same.
So what would happen if you got men to take 25 mg or 50 mg exemestane daily for a year? And if those men were to do weight training as well?
The effects on lipid serum levels of a 2-year adjuvant treatment with exemestane after tamoxifen in postmenopausal women with early breast cancer.
The third-generation aromatase inhibitor exemestane represents a new development in the treatment of estrogen-positive breast cancer. The aim of this study was to evaluate the effects on lipid profile and body composition of the shift from tamoxifen to exemestane.
After 2-3 years of tamoxifen adjuvant treatment, 68 postmenopausal women were randomly assigned to either continue tamoxifen 20 mg/day (n = 35) or to switch to exemestane 25 mg/day (n = 33).
No significant changes in lipid profile were found in patients continuing on tamoxifen. In the exemestane group, serum HDL-cholesterol (HDL-C) and triglycerides (TG) decreased significantly (p < 0.01) and serum LDL-cholesterol (LDL-C) increased significantly (p < 0.05) with respect to baseline. The difference between the two groups was significant. Moreover, in the exemestane group, fat mass (FM) and fat-free mass (FFM) showed an opposite trend, which determined a progressive and significant increase in the FFM/FM ratio.
This study shows that the choice of first-line treatment or adjuvant therapy for breast cancer should also take the individual lipid and body composition profile into account.
PMID: 19046724 [PubMed – indexed for MEDLINE]