A synthetic nonapeptide analogue of gonadotropin-releasing hormone. Leuprolide binds to the gonadotropin releasing hormone (GnRH) receptor and, after prolonged administration, inhibits endogenous secretion of gonadotropin, resulting in suppression of sex hormone production in the ovary and testes. This agent reduces testosterone production to castration levels and may inhibit androgen receptor-positive tumor progression. (NCI04)