Anti-estrogene activity agences

Representors of these group are: aromatase inhibitors, clomiphene, cyclofenil, tamoxifen. These substances are prohibited for males.

Substances with anti-estrogene activity are usually used during and after use of anabolic steroids.

High levels of estradiol can supreme gonadotropins(including LH) through negative feedback, on level hypothalamus-pituitary gland. Clomiphene and tamoxifen increase secretion of luteinizing hormone(LH), by blocking estrogene receptors, and by stopping the mechanism of negative feedback. Estradiol levels are returned to normal values after 3 weeks from stop of anabolic steroids intake, and for testosterone 12 and more weeks lasts cleaning period. So anti-estrogenes can be useful. Other reason for use of these agences is prevention from gynecomastia. 

“Doping in sport”, Marina Djordjevic Nikic