A clinician's guide to the use of gonadotropin-releasing hormone analogues in women.

Gonadotropin-releasing hormone (GnRH) and its analogues have been extensively used in clinical medicine since they were identified and synthesized in 1971. Native GnRH stimulates gonadotrophs of the anterior pituitary and has been used for induction of ovulation. The GnRH agonists, which have greater potency and a longer half-life than native GnRH, produce an initial stimulation of pituitary gonadotrophs that results in secretion of follicle-stimulating hormone and luteinizing hormone and the expected gonadal response. This response is followed by downregulation and inhibition of the pituitary-gonadal axis. The GnRH antagonists promptly suppress pituitary gonadotropin by GnRH-receptor competition, thereby avoiding the initial stimulatory phase of the agonists. Discontinuation of GnRH antagonist treatment leads to a rapid and predictable recovery of the pituitary-gonadal axis. The GnRH analogues are potent therapeutic agents that are considerably useful in a variety of clinical indications. These indications include management of endometriosis, uterine leiomyomas, hirsutism, dysfunctional uterine bleeding, premenstrual syndrome, assisted reproduction, and some hormone-dependent tumors.