Anti-estrogens

Most kinds of anti-estrogens have the following biological actions:


 * SERMs: Often used in breast cancer treatment and to treat gynecomastia. Effects estrogen receptors differently in different tissue.
 * Aromatase inhibitors: Prevents testosterone from being converted to estrogen. See steroidogenesis.
 * Estrogen receptor inhibitors: Inhibits the estrogen receptor body-wide.

Almost all of the above anti-estrogens are used to treat breast cancer.

The only notable exceptions to these mechanisms are GnRH blockers (which lower estrogen in those with ovaries), and the medicine danazol. Danazol both inhibits production of GnRH and is an anti-estrogen that blocks FSH and LH in those with ovaries. Danazol also has mild androgenic effects and possibly binds to androgen receptors and progesterone receptors.

Aromatase inhibitors are used as a last resort (or with conjunction with SERMs) in the treatment of some estrogen dependent disorders. Selective aromatase inhibitors only lower estrogen levels and not those of any other steroid produced by the adrenal gland.

Some SERMs are used in the treatment of gynecomastia, as the majority of them prevent estrogen from being used in the breasts.

Letrozole (an estrogen inhibitor) has been shown to prevent growth plate fusion, so doctors sometimes use it in conjunction with growth hormone to help short children and teens gain height. It elevates LH but does not increase FSH.

Anastrozole has been used for effective gynecomastia treatment, however, exactly how it does this is unknown.

Clomifene acts as both an estrogen and an anti estrogen. Its exact mechanism of action is unknown, but it stimulates GnRH production and LH and FSH production.

List of medications/compounds

 * SERMs: Include compounds like Raloxifene, Tamoxifen, Afimoxifene, and Clomifene
 * Aromatase inhibitors (selective): Anastrozole, Letrozole, Exemestane
 * Estrogen receptor inhibitors: Fulvestrant. Fulvestrant downgrades (damages) estrogen receptors.
 * GnRH inhibitor and androgen: Danazol