n. an analog of gonadotropin-releasing hormone that opposes the action of androgens and estrogens through inhibition of gonadotropin secretion. It is used for the treatment of uterine tumors, some forms of precocious puberty, and advanced prostate cancer. Because of its potent antiandrogen effects, it has been used controversially to perform chemical castration in repeat sex offenders. U.S. trade name (among others): Lupron.