Goserelin is an GnRH analogue. It is chemically similar to the body's natural GnRH though it has a greatly extended half-life. After administration, peak serum concentrations are reached in about two hours. It rapidly binds to the GnRH receptor cells in the pituitary gland thus leading to an initial increase in production of luteinizing hormone and thus leading to an initial increase in the production of corresponding sex hormones. Eventually, after a period of about 14-21 days, production of LH is greatly reduced due to receptor downregulation, and sex hormones are generally reduced to castrate levels.