Exemestane (Aromasin) is an oral steroidal aromatase inhibitor (but also known uniquely as an aromatase inactivator) used in the adjuvant treatment of hormonally-responsive (also called hormone-receptor-positive, estrogen-responsive) breast cancer in postmenopausal women. An aim in the treatment of hormone-receptor-positive patients in preventing recurrence is to lower estrogen levels that this breast cancer thrives on.
The main source of estrogen is the ovaries in premenopausal women, while in post-menopausal women most of the body's estrogen is produced in the adrenal gland from the conversion of androgens into estrogen by the aromatase enzyme. Exemestane is an irreversible, steroidal aromatase inactivator, structurally related to the natural substrate androstenedione. It acts as a false substrate for the aromatase enzyme, and is processed to an intermediate that binds irreversibly to the active site of the enzyme causing its inactivation, an effect also known as "suicide inhibition." In other words, the Exemestane, by being structurally similar to the target of the enzymes, permanently binds to those enzymes, thereby preventing them from ever completing their task of converting androgens into estrogen.
Aromasin averages an 85% rate of estrogen suppression, so it´s clearly a very effective agent for bodybuilders and other athletes wanting to avoid estrogen related side effects such as gyno, acne, or water-retention brought on by aromatizing steroids. Specifically, Exemestane dose this by selectively inhibiting aromatase activity in a time-dependent and irreversible manner.
As with most of the compounds in this class, it also causes a reasonable rise in testosterone levels. As an added benefit, exemestane not only increases testosterone and lowers estrogen, but it also increases IGF levels. Additionally worth noting is that Aromasin may possibly be less harsh on blood lipids than some of the other (similar) compounds we use in the world of bodybuilding or athletics (other AI´s). It also has, at best no effect on IGF, and at worst could lower it. AI´s are very tricky with regards to inconsistencies in IGF levels.
You need to take Exemestane for a week to reach steady blood plasma levels of it, and exemestane has a ½ life of 27 hours. At the dose of 20-25mgs/day Aromasin will raise your testosterone levels by about 60%, and also help out your free to bound testosterone ratio by lowering levels of Sex Hormone Binding Globulin (SHBG), by about 20% , SHBG is that nasty enzyme that binds to testosterone and renders it useless for building muscle.
The ability of exemestane to lower estrogen levels by the aforementioned 85% makes it a very nice choice for use in any cycle where aromatizing steroids are used. In addition, since it´s not too harsh at all on blood lipid profiles, it´s a very good choice for longer cycles. It´s ability to raise both testosterone levels also seem to suggest that it would be a very nice addition to a Post-Cycle-Therapy (PCT).
Store in temperature not exceeding 77oF(25oC), away from excess moisture.