Anastrozole Overview & Features

Overview and History of Arimidex

Arimidex belongs to a class and category of drugs known as Aromatase Inhibitors (AIs).

Aromatase Inhibitors fall under an even broader class of drugs known as anti-estrogens.

Another sub-category of drugs that falls under the anti-estrogen category are known as Selective Estrogen Receptor Modulators (SERMs), such as Nolvadex and Clomid.

Aromatase Inhibitors and SERMs make up the anti-estrogen class.

Aromatase Inhibitors differ greatly from SERMs in their mechanism of action and how they deal with the issue of estrogen control.

The misconception that SERMs, like Nolvadex and Clomid, serve to lower estrogen levels must first be addressed.

This is a rumor that has only recently begun to die down in the anabolic steroid-using community, but it still persists.

SERMs serve to block the action of estrogen at the receptor sites by occupying the receptor sites in place of estrogen, so that estrogen itself cannot exert its effects in breast tissue through receptor site binding.

Conversely, SERMs will also act as estrogens at receptor sites in other cells in other areas of the body (in the liver, for example, in the case of Nolvadex).

SERMs do not lower circulating levels of estrogen in blood plasma.

Aromatase Inhibitors act by eliminating the production of estrogen by binding to and disabling the aromatase enzyme, which is the enzyme responsible for the conversion (or aromatization) of androgens into estrogen.

Arimidex was originally synthesized and designed as an Aromatase Inhibitor developed by Zeneca Pharmaceuticals (now AstraZeneca) for the treatment of female patients with advanced breast cancer.

It was released onto the American prescription drug market in 1995 after gaining FDA approval for its use.

Arimidex is considered one of the newer Aromatase Inhibitors, known as a third-generation Aromatase Inhibitor[1].

The reason Aromatase Inhibitors and SERMs block the effects of estrogen in different ways is that it was discovered that most breast cancers are stimulated and aggravated by estrogen.

Arimidex is known as an ancillary treatment in the treatment of breast cancer.

This refers to a treatment that is generally used as an add-on when other standard treatments have failed to meet appropriate expectations.

Before Arimidex was developed and released as a breast cancer treatment, the drug primarily used for treatment for decades was Nolvadex (Tamoxifen).

Nolvadex is known to be utilized as the primary and standard treatment for breast cancer patients.

When Nolvadex treatment falls short of expectations for various reasons during breast cancer therapy, a secondary ancillary drug such as Arimidex is used.

In one study on Arimidex involving over 9,000 post-operative female breast cancer patients, it was observed that Arimidex showed a much more favorable outcome compared to Nolvadex (both alone and when used concurrently)[2].

This study, conducted in 2002, concluded that Arimidex was much more effective in the regression of the cancer, and also increased survival rates in post-treatment breast cancer patients[3].

It was only natural that through this and other studies, the anabolic steroid-using community took notice of Arimidex and began to research its powerful estrogen-suppressing effects.

Subsequent studies showed that while the risk of breast cancer recurrence was reduced by 40% with the use of Arimidex, patients exhibited an increase in bone fractures[4].

This is because estrogen plays a key role in the proper maintenance and mineral retention in bone, and with a large reduction in estrogen levels due to Arimidex administration, this function is significantly reduced.

Because Arimidex was the first Aromatase Inhibitor that many bodybuilders took notice of, it is the most popular Aromatase Inhibitor used among anabolic steroid users for the purpose of estrogen control.

It is used among athletes who use anabolic steroids to control nearly all estrogen-related side effects: gynecomastia, water retention and bloating, and rising blood pressure (as a result of increased water retention from estrogen).

This is in contrast with SERMs like Nolvadex, which only serve to block gynecomastia.

In fact, studies have demonstrated that the use of Arimidex in men has proven to be so effective that a dose of only 0.5 – 1mg daily is capable of reducing serum estrogen levels by 50%[5].

This is a very large reduction for males, but is quite different from the 80% reduction in female breast cancer patients, though one must remember that estrogen and female physiology are different from that of males.

Aside from its use for bodybuilders, Arimidex has also been used medically in men as well[6].

Some men exhibit abnormally high estrogen levels for a variety of reasons, and Arimidex has been utilized to treat these conditions.

Specifically, Arimidex has been used to treat male adolescents who exhibit excessive estrogen levels during puberty, which can cause unwanted pubertal gynecomastia[7] [8].

Furthermore, excessive estrogen levels in pubertal male adolescents can often result in stunted growth, as estrogen plays a key role in fusing the growth plates in bones, which halts any further linear growth, and Arimidex has been used to treat this condition as well[9] [10].

Chemical Characteristics of Arimidex

Arimidex is a non-steroidal Aromatase Inhibitor.

This means that it does not possess the characteristic four-ring cycloalkane carbon structure that is common to all steroids.

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Properties of Arimidex

The effects of Arimidex on controlling serum estrogen levels are quite significant, even with a dose of 1mg daily.

The estrogen suppression from this dose has been demonstrated in over 80% of patients.

Because Arimidex is so effective at reducing estrogen levels by inhibiting the aromatase enzyme, it is typically administered only to post-menopausal women or in cases where other primary breast cancer treatments have failed.

Arimidex and Letrozole are both classified as non-steroidal and non-suicidal Aromatase Inhibitors, which compete with the substrate for binding to the enzyme’s active site.

This is a very different concept from Aromasin (Exemestane), which is a steroidal and suicidal Aromatase Inhibitor that acts as a mechanism-based inhibitor, mimicking the substrate and being converted by the enzyme to a reactive intermediate, which results in the inactivation of the aromatase enzyme.

To put it simply, this means that Aromasin’s chemical structure resembles the traditional ‘target’ that aromatase binds to (e.g., testosterone) and it essentially ‘fools’ the aromatase enzyme into binding with it, only to be inhibited/deactivated.

Because the binding strength is so strong, this inhibition is permanent for the aromatase enzyme that Aromasin has bound to.

Because Arimidex and Letrozole are non-suicidal Aromatase Inhibitors, they compete with the enzyme’s traditional ‘target’ instead of securing a permanent spot (an advantage Aromasin has over the other two).

Bodybuilders and athletes using anabolic steroids favor Aromatase Inhibitors like Arimidex for their ability to eliminate the root cause of rising estrogen levels: aromatase.

By disabling the aromatase enzyme, supra-physiological levels of aromatizable androgens such as Testosterone, Dianabol, Boldenone, etc., cannot be converted into estrogen, eliminating the risk of estrogen-related side effects.

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Arimidex Side Effects

Arimidex (Anastrozole) is a compound that is generally well-tolerated by male users, as it is an ancillary compound intended for the purpose of controlling estrogen in the body.

However, there are some Arimidex side effects to be concerned about.

These exist primarily in the form of an excessive reduction of estrogen plasma levels in the body and long-term estrogen suppression.

Arimidex affects women in a much greater and more significant way than it does male users.

It must be understood that with regard to estrogen reduction and suppression, Arimidex belongs to the Aromatase Inhibitor family, unlike SERMs (Selective Estrogen Receptor Modulators) such as Nolvadex or Clomid (Clomiphene Citrate).

This means that it serves to disable the aromatase enzyme, which is responsible for the aromatization, or conversion, of Testosterone into estrogen.

In other words, Arimidex reduces the total circulating estrogen levels at the root cause, unlike SERMs which serve to block the activity of estrogen at specific receptor sites.

Studies have demonstrated that the use of Arimidex increases the incidence and chances of bone fractures.

While this is a female-specific side effect from Arimidex use, estrogen also plays an important role in promoting and maintaining bone mineral density in men.

Studies have shown that even short-term use of Arimidex negatively impacts calcium turnover in bone tissue.

Lethargy and fatigue are commonly associated with Arimidex use.

As with almost all estrogen-reducing compounds, a reduction in circulating estrogen levels can lead to chronic fatigue due to the diminished crucial role that estrogen plays in the central nervous system.

This is usually the result of estrogen levels being reduced to unhealthy levels.

One particularly prominent side effect of Arimidex use is its negative impact on blood cholesterol levels.

Like nearly all estrogen-reducing compounds, Arimidex also reduces HDL (good cholesterol) and increases LDL (bad cholesterol).

This is because estrogen plays a role in promoting healthy cholesterol levels in the body, and when plasma levels of estrogen are not maintained at normal levels, this action ceases.

It goes without saying, of course, that the more severe the reduction in estrogen, the more severe the impact on the cardiovascular system.

One significant side effect of Arimidex is the potential for estrogen rebound.

This exists especially with two of the three most popular Aromatase Inhibitors (Arimidex and Letrozole).

The third Aromatase Inhibitor, Aromasin (Exemestane), does not share this same property of potential estrogen rebound.

This is because, unlike Aromasin, Arimidex is a non-suicidal Aromatase Inhibitor.

This means that Arimidex binds with and disables the aromatase enzyme, but not permanently.

At some point, Arimidex will dissociate from the enzyme, and the enzyme will once again be free to do its job in the body.

What this means for the end-user is that if Arimidex use is discontinued too quickly or abruptly after its initiation, there is a risk of estrogen levels rebounding (and thus, estrogen-related side effects).

Dosage and Administration of Arimidex

Medically, Arimidex (Anastrozole) is used as a treatment for post-menopausal female breast cancer where estrogen has been identified as the primary culprit.

In these cases, the prescribed dosage and administration of Arimidex is 1mg once per day until the progression of the cancer is halted.

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Arimidex On-Cycle for Gynecomastia and Estrogen Control

For gynecomastia control and general on-cycle estrogen control, Arimidex should typically be used in the range of 0.5 – 1mg per day, which can be adjusted depending on the user’s tolerance and response to the compound.

Every individual must adjust their Arimidex dosage according to their personal response.

It is not uncommon for 0.5mg per day to be either too much or too little for some individuals.

It should also always be remembered that the goal here is to control estrogen during a cycle, not to completely eliminate estrogen levels.

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Arimidex for Post Cycle Therapy (PCT)

Since Arimidex has been shown in studies to aid in the endogenous natural Testosterone production in men, a dosage of 0.5mg – 1mg per day of Arimidex during PCT should be sufficient.

It is also important to understand that Arimidex has a half-life of approximately 48 hours, and it takes a full week (7 days) of consistent administration to reach peak blood plasma levels.

Arimidex can be taken at any time of day, with or without food.

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Legality and Availability of Arimidex

Arimidex is an unscheduled substance in the vast majority of countries across the world.

In Canada and the United States in particular, it is a prescription-only product but is not a controlled substance, meaning it is legal to own, purchase, and possess, but cannot be bought domestically without a prescription.

The legality of Arimidex is the same in the United Kingdom.

In many countries in Eastern Europe, Asia, and the Middle East, Arimidex can often be purchased over-the-counter.

Anastrozole (AKA Arimidex)