Gonadotropin-releasing Hormone Analogue - Agonists

Agonists

A gonadotropin-releasing hormone agonist (GnRH agonist) is an analogue that activates the GnRH receptor resulting in increased secretion of FSH and LH. Initially it was thought that agonists could be used as potent and prolonged stimulators of pituitary gonadotropin release, but it was soon recognized that agonists, after their initial stimulating action – termed a “flare” effect - eventually caused a paradoxical and sustained drop in gonadotropin secretion. This second effect was termed “downregulation” and can be observed after about 10 days. While this phase is reversible upon stopping the medication, it can be maintained when GnRH agonists use is continued for a long time.