Elagolix sodium (NBI56418; ABT-620; Orilissa), the sodium salt of Elagolix, is an orally bioavailable and small molecule antagonist of the gonadotropin-releasing hormone receptor (GnRHR) (KD = 54 pM) approved on 7/23/2018 by FDA for the management of moderate to severe pain associated with endometriosis. Elagolix is a short-acting GnRH antagonist that suppresses ovarian estrogen production in a dose-dependent manner, meaning that higher doses result in full suppression while lower doses only cause partial suppression. Elagolix's non-peptide structure and oral bioavailability make it the leader of a new class of GnRH inhibitors known as second-generation inhibitors.