Arimidex
Anastrozole is used with other treatments, such as surgery or radiation, to treat early breast cancer in women who have experienced menopause (change of life; end of monthly menstrual periods). This medication is also used in women, who have experienced menopause, as a first treatment of breast cancer that has spread within the breast or to other areas of the body. This medication is also used to treat breast cancer in women whose breast cancer has worsened after taking tamoxifen (Nolvadex). Anastrozole is in a class of medications called nonsteroidal aromatase inhibitors. It works by decreasing the amount of estrogen the body makes. This can slow or stop the growth of many types of breast cancer cells that need estrogen to grow.
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Arimidex is an aromatase inhibitor used to lower circulating estrogen. It was developed to help fight breast cancer as estrogen plays a role in the growth of cancer cells. Arimidex binds reversibly to the aromatase enzyme through competitive inhibition. This suppresses the conversion of androgens into estrogen. Circulating plasma estrogen can be reduced by nearly 85% in women using Arimidex. A common misconception is that aromatase inhibition is similar in men than women. However in trials when males were administered 1mg of Arimidex daily, circulating estrogen was only reduced by about 50%. Anastrozole is rapidly absorbed orally (time to reach maximum concentration, 1 h) with a slow apparent clearance of 1.54 liters/h and a terminal half-life of 46.8 h. Because Arimidex reversibly binds to the aromatase enzyme, once you stop taking it the aromatase enzyme is free to convert androgens such as testosterone into estrogen again. This is sometimes referred to as estrogen rebound. Other aromatase inhibitors like Aromasin are irreversible and therefore will not result in an estrogen rebound.

Figure 1. Changes in testosterone and E2 concentrations in normal young men (—22 yr old) before () and after 10 days of oral anastrozole at 0.5 and 1 mg.
Arimidex not only lowers circulating estrogen but it also increases LH and FSH concentrations in the blood in addition to increasing testosterone by about 58% in men as a result of the elevated signal hormones. In one study elderly men with mild hypogonadism were administered 1mg daily of Arimidex for 12 weeks, the treatment normalized serum testosterone levels in men without adversely affecting lipids, inflammatory markers of cardiovascular risk, or insulin resistance.
Arimidex can be employed during a steroid cycle when aromatizing compounds such as testosterone are administered in order to control estrogen from getting out of control. During the course of a typical steroid cycle estrogen can rise quite high. Estrogen has been measured as much as 7 times higher than normal in men on steroids. This is excessive and can potentially cause water retention, gynecomastia (the formation of female breast tissue) or benign prostatic hyperplasia. Therefore in order to avoid these side effects estrogen must be controlled. Reduction in breast area and breast volume have been observed in young men treated for 6 months with Arimidex (1 mg daily). These subjects had recent preexisting gynecomastia (less than one year). However boys with longstanding gynecomastia (more than one year) were unresponsive to 6 months of Arimidex treatment, possibly due to development of dense breast fibrosis. Therefore using Arimidex to treat recent gynecomastia is supported by the data. The only drug known to have some (possible) effect on this dense tissue is the aromatase inhibitor Letrozole.
Arimidex may be used as a testosterone supplement, a gyno prevention tool while on cycle, or simply a drug to keep estrogen levels low during a steroid cycle. But for most uses, there seem to be better alternatives. Because of Arimidex’s reversible trait, it is normally recommended to look at suicidal inhibitors such as Exemestane. It is also strongly reccomended to supplement Arimidex with Tamoxifen when dealing with gynecomastia issues. When it comes to testosterone supplementation without exogenous testosterone, estrogen levels may dip too low (which yes is possible and problematic in men) and cause many bodily function issues. But what it lacks in versatility it makes up in raw power. Arimidex is known as the second most powerful and most used on cycle AI on the market. This is because during more intense cycles it is seen that drugs such as exemestane simple cant keep estrogen levels lower like Arimidex. This makes Arimidex an excellent choice for those on cycles of larger doses of testosterone that exemestane simple cant keep up with.
References
1. Effect of aromatase inhibition on lipids and inflammatory markers of cardiovascular disease in elderly men with low testosterone levels.
2. Estrogen suppression in males: metabolic effects.
3. Pharmacokinetics and pharmacodynamics of anastrozole in pubertal boys with recent-onset gynecomastia.
4. Influence of Neoadjuvant Anastrozole (Arimidex) on Intratumoral Estrogen Levels and Proliferation Markers in Patients with Locally Advanced Breast Cancer
© John Connor et al.