As can be surmised by the commonly used term anti-estrogen, the primary goal of therapy with an estrogen maintenance drug is to block the side effects associated with this hormone from becoming apparent during steroid use (though often they are also used at the conclusion of a cycle to help restore the release of endogenous testosterone). For the purpose of combating estrogen a number of substances have been used successfully over the years, and more have recently become available due to advances in the field of breast cancer research (treatment of breast cancer is the primary clinical use for most of these agents).
Likewise the athlete now has several pharmaceutical options to select from when shopping, which can make the choice of what drug may be best for any particular case a confusing one. Since a number of issues including cost, availability, potential side effects and efficacy may factor into this decision, I thought a closer look at both the old and newer agents might be in order.
Aromatization is the technical term for it. It is a natural process in which an androgen (male sex hormone) such as testosterone can be converted to an estrogen (female sex hormone) in the human body. In normal situations of course the male body will produce estrogens only in very small amounts, though they still do play an important role metabolically (including visceral/organ fat disposition, bone growth/maturity and blood lipid regulation). Athletes however may find that estrogen can become an extremely dramatic problem with the administration of anabolic/androgenic steroids. With the natural process of aromatization in place, and extremely heightened androgen level can result in a troubling buildup of estrogens. This may cause the onset of estrogen related side effects such as
noticeable fat and water retention, as well as the buildup of female breast tissue (gynecomastia). Gynecomastia is a particularly upsetting occurrence for the steroid-using male athlete, as the characteristic unsightly buildup of tissue mass is usually permanent. Although many synthetic anabolic agents are resistant or not open to the process of aromatization at all, our standard bulking drugs such as testosterone and Dianabol are still readily aromatized. This has prompted the athletic community to seek the benefit of estrogen maintenance drugs when taking such steroids, a class of medications that are now considered standard remedies in the athletes’ drug arsenal.
Nolvadex and Clomid
Estrogen receptor antagonists, more simply referred to as anti-estrogens (though this term is often loosely applied to all estrogen maintenance drugs), are drugs that block estrogens from exerting activity in the body. This is actualized by the ability of a particular substance to bind to a segment of the estrogen receptor, yet not activate it. This in turn prevents other estrogens from binding and activating the same receptor site. In a clinical setting an estrogen antagonist, most prominently the drug tamoxifen citrate (sold under the brand name Nolvadex) is typically used as the first line of defense during advanced breast cancer therapy. Its use can efficiently deprive estrogen responsive cancer cells of necessary hormone, allowing a high rate of response in patients with such forms of cancer. Stronger agents such as aromatase inhibitors (discussed below) are usually a second choice, substituted when conventional anti-estrogen therapy fails to elicit the desired response. A drug like tamoxifen is preferred over other agents as the first course of breast cancer treatment for a number of reasons, most due to the fact that that it is both extremely effective yet does not inhibit the actual formation of estrogen in the body. Among other things, this may allow Nolvadex therapy to be somewhat more comfortable for the patient. Although many women (particularly pre-menopausal) seem to suffer menopausal-like side effects with virtually all estrogen maintenance drugs, estrogen antagonists are often somewhat more tolerable than agents that block the synthesis of estrogen. In fact the activity of tamoxifen is
itself variable, such that in certain target tissues it may actually act as an agonist (activator) of the estrogen receptor. It therefore does not completely diminish the biological activity of estrogens, though it does considerably reduce it nonetheless. It is also well understood in medicine today that estrogens play a supportive role in the cardiovascular system. For example, studies show that a rise in the estrogen level (as in post-menopausal estrogen replacement therapy) is typically linked with a reduction in LDL (bad) cholesterol, and a rise in HDL (good) cholesterol. The ability of tamoxifen to act as an estrogen agonist in the liver likewise gives it what may be its most welcome property, namely that it exhibits an estrogenic, rather than antiestrogenic, effect on blood lipid (cholesterol) values. This trend should reduce an important risk factor for heart disease, obviously a welcome effect during treatment. For the steroid-using athlete already faced with negative alterations in lipid profiles, such an effect could obviously an important consideration. Clomid (clomiphene citrate) is very similar in structure to Nolvadex. As well as we see with Nolvadex, Clomid is a partial agonist/antagonist of the estrogen receptor depending on the target tissue in question. Although athletes most commonly think of Clomid as a testosterone-stimulating drug only (another effect of antiestrogenic compounds), to be used at the conclusion of steroid treatment, its activity in the human body is not at all dissimilar to Nolvadex. It should likewise be thought of not as a drug with its own niche of use, but instead as another efficient remedy for gynecomastia similar to Nolvadex (with the related ability to support the release of testosterone). It could clearly replace Nolvadex as a preventative measure against gynecomastia during cycles with aromatizable steroids
without noticeably altering the level of effect received, just as Nolvadex can be used effectively to increase the synthesis of testosterone in the body at the conclusion of steroid use (though admittedly Nolvadex may be slightly more potent in both regards).
Aromatase Inhibitors
Aromatase inhibitors are another, perhaps more direct, way of dealing with estrogen in the body. Instead of blocking estrogen at its receptor, these agents have the more direct task of targeting the enzyme responsible (aromatase) for the biosynthesis of estrogen. By inhibiting this enzyme, circulating levels of estrogen can be efficiently and significantly reduced. Athletes will likewise find that the more recently developed aromatase inhibitors are the most potent remedies available for the prevention of related side effects. Before detailing the various inhibitors of aromatase it is important to discuss further the potential drawbacks to this type of therapy. The most prominent being a negative impact on cholesterol profiles. Although steroid use is of course expected to negatively effect cholesterol levels, we find that when aromatization is inhibited this harmful tendency is greatly enhanced.
Alternately choosing an antiestrogen such as Nolvadex however does not offer us a 100% guarantee that lipid values will not worsen over using no estrogen maintenance drug at all. In studies combining tamoxifen with estrogen replacement therapy for instance, it was shown that this compound could interfere with the beneficial effects of estrogen-based drugs on lipid values, though not completely diminish them. Since the effects of Nolvadex during treatment with a steroid such as testosterone have not been fully investigated (admittedly it is a small and not legitimately supported corner of use for tamoxifen), it remains to be seen whether or not it is truly beneficial in terms of lipid values when given with an aromatizable steroid. For now however, should an estrogen maintenance drug be
indicated, we can still consider it to be a safer alternative to any of the following aromatase inhibitors.
Proviron (mesterolone)
Proviron is not technically classified as an anti-aromatase, but is an oral androgenic steroid. Specifically it contains a derivative of the potent steroid dihydrotestosterone, differing only by the addition of 1 methylation (the same alteration used to increase the oral efficacy of Primobolan). Its use as an antiaromatase stems from studies showing a nonaromatizing androgen such as dihydrotestosterone may interfere with this enzyme reaction. It is believed to interfere with aromatase by competing with an aromatizable steroid such as testosterone for binding to the enzyme site. With dihydrotestosterone (or Proviron) interacting with this enzyme, yet producing no reaction, the enzyme is temporally prevented from altering other hormones, and an anti-estrogenic effect is achieved.
Overall however, Proviron is much less reliable than any one of the mentioned antiestrogens or aromatase inhibitors. Though it may add some benefit when taken concurrently with a drug such as tamoxifen (though in such a case tamoxifen would be doing most of the work), I don’t think that it is potent enough as an aromatase inhibitor to recommend using along during strong cycles.
Arimidex (anastrozole)
Anastrozole is a much more recently developed, selective, non-steroidal aromatase inhibitor. It represents quite an advance in breast cancer treatments, as it can efficiently block aromatase activity without affecting enzymes involved in the biosynthesis of other adrenal steroids (hence the term selective). Its activity is therefore much more specific than aminoglutethimide, a trait that also makes it more tolerable for the patient. Numerous studies also support the superiority of this inhibitor over previously prescribed treatments, including many in which patients responded favorably to anastrozole (as a second-line therapy) after ceasing to respond to tamoxifen. In fact of all the aromatase inhibitors discussed in this article, Arimidex is shown to be the most effective and reliable.
The recommended dosage for anastrozole clinically is a single 1mg tablet daily. This is the lowest dose shown to produce maximum suppression of estrogen levels, and to spite expectations of greater results, doses of up to 10mg daily were not shown to appreciably increase the long-term response rate. In many cases the 1mg dose will produce estrogen suppression near 100%, so there seems to be little need for the athlete to venture higher.

