GnRH Agonists and Antagonists in Endometriosis and Adenomyosis Therapy

Endometriosis and adenomyosis are estrogen dependent disorders and hence, one of the major pillars in their medical management has been to suppress circulating estrogen levels. Given that the primary source of premenopausal endogenous estrogen is estradiol production from the ovaries, the principal mechanism for estrogen suppression has been through inhibition of the hypothalamic-pituitary-ovarian (HPO) axis with GnRH agonists. Over the last 15–20 years, GnRH antagonists have also been developed for this purpose. This chapter will provide an overview of the use of GnRH agonists and antagonists for the treatment of endometriosis and adenomyosis.