Letroxyl (Letrozole) is a non-steroidal selective third generation aromatase inhibitor. The structure and activity of this compound are very similar to that of Arimidex (anastrozole), and it is prescribed for similar medical purposes. More specifically, U.S. prescribing guidelines for letrozole recommend it be used for the treatment of post menopausal women with estrogen receptor-positive or estrogen receptor-unknown (unsure if the cancer is responsive to estrogen) breast cancer. It is typically used as a secondline of treatment after an estrogen-receptor antagonist like tamoxifen has failed to elicit a desirable response, although it is sometimes initiated as the first course of therapy depending on the circumstances. Male bodybuilders and athletes find value in letrozole for its ability to mitigate the estrogenic side effects associated with the use of aromatizable anabolic/androgenic steroids, such asgynecomastia, fat buildup, and visible water retention. Letrozole represents one of the newer achievements in a long line of drugs targeting aromatase inhibition. It is among the most potent estrogen-lowering drugs developed to date, and has an effects ignificantly stronger than non-selective first generation aromatase inhibitors like Teslac and Cytadren. The dosage of each tablet of Femara is 2.5 milligrams, which according to product information was sufficient to lower estrogen levels by an average of 78% during clinical trails. The drug, however, appears to often remain quite effective in lower doses. The package insert for the product it self comments that during clinical studies doses as low as .1 and .5 milligrams produced 75 and 78% estrogen inhibition, respectively in many patients. The recommended dose, like wise, reflects a level that seems to elicit a desired level of inhibition in nearly all patients. A large number of people may, therefore, respond well to lower doses of the drug. Letrozole is classified as a non-steroidal selective third generation aromatase inhibitor. It has the chemical designation 4,4’(1H-1,2,4-Triazol-1- ylmethylene) dibenzonitrile.
Letrozole is FDA approved for 1) adjuvant treatment of post menopausal women with hormone receptor positive early breast cancer; 2) the extended adjuvant treatment of early breast cancer inpost menopausal women who have received 5 years of adjuvant tamoxifen therapy; 3) first-line treatment of post menopausal women with hormone receptor positive or hormone receptor unknown locally advanced or metastatic breast cancer; and 4) the treatment of advanced breast cancer inpostmenopausal women with disease progression following anti-estrogen therapy. The recommended dose of letrozole is one 2.5 mg tablet administered once per day, without regard to meals. When used (off-label) to mitigate the estrogenic side effects of anabolic/androgenic steroid use or increase muscle definition, male athletes and bodybuilders often take 1.25 mg to 2.5 mg per day. In some cases a dosage of a half of a tablet (1.25 mg) taken every other day is sufficient to prevent the on set of estrogenic side effects.
