GnRHi

GnRHi, also known as GnRH agonist, is a medication that mimics the action of gonadotropin-releasing hormone (GnRH). GnRH is a hormone produced in the hypothalamus that signals the pituitary gland to release luteinizing hormone (LH) and follicle-stimulating hormone (FSH). These hormones, in turn, regulate the production of sex hormones like testosterone and estrogen by the gonads.

Initially, GnRHi stimulate the release of LH and FSH, leading to a temporary increase in sex hormone levels. However, with continuous administration, GnRHi cause the pituitary gland to become less responsive to GnRH. This desensitization results in a significant decrease in LH and FSH production, and consequently, a profound suppression of testosterone or estrogen levels. This effect is often referred to as medical castration.

GnRHi are used in various medical conditions. In men, they are primarily employed to treat prostate cancer by reducing testosterone levels, which can slow the growth of hormone-sensitive tumors. They are also used in precocious puberty, a condition where children begin puberty too early, to delay the onset of sexual development. In women, GnRHi can be used to manage endometriosis, uterine fibroids, and certain types of breast cancer by suppressing estrogen production. They are also utilized in assisted reproductive technologies, such as in vitro fertilization (IVF), to control the timing of ovulation.

GnRHi are typically administered via injection, either intramuscularly or subcutaneously, with varying dosing schedules depending on the specific medication and the condition being treated. Common side effects can include hot flashes, fatigue, decreased libido, and mood changes, reflecting the hormonal alterations induced by the medication.