Gonadotropin-Releasing Hormone (GnRH) is produced by the hypothalamus and plays a crucial role in the regulation of the reproductive system by controlling the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the pituitary gland. The release of GnRH leads to the secretion of FSH and LH, which in turn stimulate the production of estrogen and progesterone in females and testosterone in males.
GnRH antagonists are a class of medications that block the action of GnRH receptors. This results in a decrease in the production of FSH and LH, which can be useful in the treatment of various conditions such as prostate cancer, endometriosis, uterine fibroids, and female infertility in assisted reproduction. GnRH antagonists such as cetrorelix are small-molecule compounds that compete with natural GnRH for binding to GnRH receptors, leading to a decrease or blockade of GnRH action in the body.
In assisted reproduction, GnRH antagonists are often used to prevent premature ovulation in women undergoing controlled ovarian stimulation (COS) for in vitro fertilization (IVF). By preventing premature ovulation, the timing of egg retrieval can be better controlled and the chances of a successful IVF cycle can be increased. GnRH antagonists can be administered by injection and are typically started during the mid-follicular phase of the menstrual cycle.