Gonadotropin-releasing hormone antagonist

Gonadotropin-releasing hormone antagonist
Drug class
Cetrorelix, one of the must widely used GnRH antagonists.
Class identifiers
Synonyms	GnRH receptor antagonists; GnRH blockers; GnRH inhibitors; Antigonadotropins
Use	Infertility; Prostate cancer; Precocious puberty; Breast cancer; Endometriosis; Uterine fibroids; Transgender people
Biological target	GnRH receptor
Chemical class	Peptides; Nonpeptides

Gonadotrophin-releasing hormone (GnRH) antagonists (receptor blockers) are a class of drugs that antagonize the gonadotropin-releasing hormone receptor (GnRHR) and thus the action of GnRH. Some are similar in structure to natural GnRH (a hormone made by neurons in the hypothalamus) but that have an antagonistic effect. These GnRH antagonists are peptide molecules that are made up multiple, often synthetically produced amino acids. Others are small-molecule, non-peptide compounds. GnRH antagonists compete with natural GnRH for binding to GnRH receptors, thus decreasing or blocking GnRH action in the body.

GnRH antagonists competitively and reversibly bind to GnRH receptors in the pituitary gland, blocking the release of luteinising hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary. In men, the reduction in LH subsequently leads to rapid suppression of testosterone release from the testes; in women it leads to suppression of estrogen release from the ovaries.

Unlike the GnRH agonists, which cause an initial stimulation of the hypothalamic-pituitary-gonadal axis (HPGA), leading to a surge in testosterone or estrogen levels, GnRH antagonists have an immediate onset of action, rapidly reducing sex hormone levels without an initial surge.

Currently approved GnRH antagonists include the following: