Arimidex (anastrozole) is a drug indicated as a treatment for postmenopausal women with certain forms of advanced breast cancer. It is an anti-estrogenic drug belonging to a new class of prescription medications called selective oral aromatase inhibitors.
This drug works by blocking an enzyme called aromatase which leads to decreased levels of estrogen in the body. Since several forms of breast cancer are stimulated by estrogen, anastrazole helps inhibit those cancerous cells and halt the progression of the disease. A similar mechanism of action is found in tamoxifen, an older drug that has the same indications. In fact, some forms of breast cancer that don’t respond favorably to tamoxifen are nowadays treated with anastrazole.
Arimidex reduced the levels of estrogen by preventing excess testosterone from being converted into estrogen as happens normally. As a result, it will increase the levels of so called “free” testosterone.
By affecting the sex hormones as described above, anastrazole helps control the levels of estrogen and therefore other conditions, such as an enlarged prostate, can be managed. In bodybuilders, this drug can prevent the abnormal enlargement of the breast in men, a condition called gynecomastia (because of the high levels of estrogen), while the benefits of extra testosterone translate into more muscle mass, reduced body fat, more energy and stamina and improved mood and libido.
However, this drug should be used cautiously because it is a potent drug and if the estrogen levels go too low it can lead to undesirable side effects. If estrogen is too low it can cause bone loss, increased LDL or bad cholesterol while decreasing the HDL or good cholesterol, all of which are conditions that can lead to osteoporosis and heart diseases. Thus, estrogen levels in the blood should be monitored.
Bodybuilders may use anastrazole along with another hormone, HCG, during training, as part of the Post Cycle therapy, although it is not approved by the FDA for this purpose. This use is based on research studies that found anastrazole reduced the levels of estrogen in the body by as much as 50%, while increasing the levels of testosterone by 60% (the latest effect occurs after only one week of treatment).
Common side effects from taking Arimidex (anastrazole) include hot flashes, joint pain, sore throat, high blood pressure, depression, nausea, vomiting, skin rash, sleep problems, headaches and increased fluid retention. Rare side effects include skin ulcers, allergic reactions, or changes in liver function. These side effects are uncommon with the low anastrazole dosing used for the adjunctive use in testosterone therapy. In animal subjects who received aromatase inhibitor drugs, there was an association with certain forms of benign and malignant tumors affecting the liver, ovary, uterus and thyroid. There is an absolute contraindication of taking anastrazole during pregnancy, as it can seriously harm the baby. In non-pregnant women, this drug may cause infertility.
This drug interacts with tamoxifen, estrogen and the anti-coagulant warfarin.