Arimidex — anastrozole


Anastrozole is an anti-estrogenic drug developed for the treatment of advanced breast cancer in women. Specifically, this agent is the first in a newer class of third-generation selective oral aromatase inhibitors. It acts by blocking the enzyme aromatase, subsequently blocking the production of estrogen in the body. Since many forms of breast cancer cells are stimulated by estrogen, reducing levels of this hormone in the body may retard the progression of the disease. This is also the fundamental use of tamoxifen citrate (Nolvadex), except Nolvadex blocks the action of estrogen at the receptor, not its actual endogenous production. The effects of anastrozole can be very substantial, with a daily dose of 1 mg (commonly 1 tablet) capable of producing estrogen suppression greater than 80% in treated patients. With the powerful effect this drug has on hormone levels, it is usually only prescribed to post-menopausal women. Side effects like hot flashes and hair thinning can present themselves during therapy, and would be much more severe in pre-menopausal patients. For the steroid-using male athlete, anastrozole is applied to minimize the side effects associated with elevated estrogen levels secondary to anabolic/androgenic steroid use. In comparison with traditional methods such as Nolvadex and Proviron, anastrozole is significantly more effective at controlling estrogen.

Brand name Arimidex, Anastrozole

Anastrozole History

Anastrozole was developed by Zeneca Pharmaceuticals, and approved for use in the United States at the end of 1995. The drug was developed as a new adjunct treatment for operable breast cancer in postmenopausal female patients, an area of medicine that had a long history of tamoxifen use. Substantial data was needed to shift prescribing trends away from such an established medication treatment. Shortly after its release, anastrozole was investigated as part of an extremely large multicenter double blind trial based out of Rome (ATAC). The study evaluated the use of anastrozole and tamoxifen, alone or in combination, in 9,366 postmenopausal women following breast cancer surgery. The results favored anastrozole over tamoxifen at promoting disease regression and improving overall survival rates. Upon publication of this trial in 2002, anastrozole emerged as a new contender for the adjunctive treatment of postmenopausal breast cancer. Around this same time the drug was also gained popularity with male bodybuilders and athletes who began taking notice of the strong estrogen suppression caused by anastrozole, both in the anecdotal reports of others and in clinical trials.

How is Anastrozole Supplied

Anastrozole is most commonly supplied in tablets of 1mg.

Structural Characteristics of Anastrozole

Anastrozole is classified as a selective non-steroidal aromatase inhibitor. It has the chemical designation 1,3- benzenediacetonitrile,a,a,a’,a’-tetramethyl-5-(1H-1,2,4- triazol-1-ylmethyl).

Anastrozole Side Effects

Common side effects associated with the use of an aromatase inhibitor include hot flashes, joint pain, weakness, fatigue, mood changes, depression, high blood pressure, swelling of the arms/legs, and headache. Aromatase inhibitors may also decrease bone mineral density, which may lead to osteoporosis and an increase in fractures in susceptible patients. Some individuals may also respond to the medication with gastrointestinal side effects including nausea and vomiting. Aromatase inhibitors can harm the development of an unborn fetus, and should never be taken or handled during pregnancy. When taken by men (as an off-label use) to reduce estrogenicity during prolonged periods of steroid treatment, aromatase inhibitors may increase cardiovascular disease (CVD) risk by retarding some beneficial properties of estrogen on cholesterol values. Studies have demonstrated that when an aromatizable steroid such as testosterone enanthate is taken in conjunction with an aromatase inhibitor, suppression of HDL (good) cholesterol levels become significantly more pronounced. Since the estrogen receptor agonist/antagonist Nolvadex generally does not display the same anti-estrogenic (negative) effect on cholesterol values, it is usually favored over aromatase inhibitors for estrogen maintenance by male bodybuilders and athletes concerned with cardiovascular health.

Anastrozole Administration

Anastrozole is FDA approved for adjunctive treatment of postmenopausal women with hormone receptor-positive early breast cancer, first-line treatment of postmenopausal women with hormone receptor-positive or receptor unknown locally advanced metastatic breast cancer, and treatment of advanced breast cancer in postmenopausal women with disease progression following tamoxifen therapy. The dosage prescribed in all instances is 1mg per day until disease progression has halted.

When used to mitigate the estrogenic side effects of anabolic/androgenic steroid use, male athletes and bodybuilders will commonly take .5 mg to 1 mg of anastrozole per day. In some instances a half of a tablet (.5 mg) taken every other day is sufficient to mitigate the buildup of estrogen. When used with readily aromatizing androgens such as methandrostenolone or testosterone, gynecomastia and water retention are often effectively blocked. Additionally, the use of anastrozole may decrease fat mass, which can also be tied to estrogen levels. The result can be a harder and much more defined appearance to the muscles and physique, which makes this agent of interest for dieting/cutting purposes as well.

It is of note that food does not appear to affect the absorption of anastrozole, so the drug may be taken with or between meals.

Anastrozole Availability

Anastrozole is widely available in the U.S. and many other nations as a prescription drug product. It is also found readily on the black market.

Anastrozole is produced by Swiss Remedies and available across Europe. Due to numerous fakes of this product, Swiss Remedies offers a convenient online product checker.

Kalpa Pharmaceuticals makes Anastrozole under the product name Arimixyl. It comes as 1 mg per tablet, 30 tablets in sachets. It is widely distributed online.


Dragon Pharma Arimidex is made in Europe. It comes as 1 mg per tablet, 100 tablets in sachets. It is widely distributed online.

dp arimidex

7Lab Pharm makes it under the product name Anastro-lab. It comes as 1 mg per tablet, 50 tablets in sachets. It is widely distributed online.


Axiolabs Arimiplex is made in Europe. It comes as 1 mg per tablet, 50 tablets in sachets. It is widely distributed online.


Magnus Pharmaceuticals makes the product Anastrazole primarily for the EU and UK markets. Due to fake products appearing on the market, Magnus offers an online checker that lets steroid users verify their product originality.

Bodybuilders reference

Arimidex is an anti-estrogen type drug. It is usually provided in 0.5 mg tabs. The drug works in a non-steroid form by inhibiting the aromatase enzyme which converts testosterone and other androgens into estrogen. This means that there is less estrogen to cause female pattern fat deposits, gyno, and water retention. In medicine, Arimidex is utilized to treat prostate cancer. In sports chemistry, the drug has been employed as a means of preventing excessive estrogenic side effects during AAS use and to aid in creating a harder appearing musculature for competitive bodybuilders. Unlike Nolvadex, which simply block estrogen receptor-sites, this drug prevents or reduces estrogen production. Though some estrogen presence is noted as necessary for AAS to reach full effectiveness, too much can cause a layer of fat, water retention, and breast tissue growth potentially with tumors called gynecomastia or bitch tits. Arimidex has a 75-85% aromatization inhibition rate.

Males who experienced excessive aromatization of AAS or who were extremely estrogen sensitive usually utilized a dosage of 0.5-3.0 mg daily. In fact, most realized excellent estrogen control with only 0.5mg/d (mg daily). Women usually showed excellent lean appearances (even in their legs) with 0.5-1.0 mg daily. Arimidex has a very short active-life so 0.5 mg dosages were often taken 2-6 times daily at equal intervals. Stacking 10-30 mg of Nolvadex with 1.0 mg of Arimidex has resulted in a near “0” estrogen activity situation regardless of the AAS protocol utilized. Directly following an AAS cycle, estrogen control has also become a problem (during periods intended for reestablishing HPTA function). In this case, the dosage was reduced from a higher starting dosage to a low dosage that was continued for 7-14 days after AAS discontinuance. This protocol was considered necessary to assure clearing of AAS induced estrogen build-up.

Newbies Research Guide reference

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 ceas- ing 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. Price would probably pre- vent such experimentation in any event, as this new therapy is quite expensive. While tamoxifen will typically cost no more than $1-1.50 dollars per tablet, the price can be as high as $10 for anastrozole. This has prompted some to tinker with lower dosages (1/2 tablet daily) or alternating schedules (often in conjunc- tion with tamoxifen) in order to stretch the money a little further.


Wlliam Llewellyn (2011) – Anabolics
L. Rea (2002) – Chemical Muscle Enhancement Bodybuilders Desk Reference
Newbies Research Guide

Your experience with Arimidex — anastrozole