Dinordrin is a synthetic A-nor steroid analog, available as Dinordrin I (the 2α,17α-diethynyl diacetate or dipropionate) and its 2β-epimer Dinordrin II. In standardized rat uterotrophic bioassays, Dinordrin I demonstrates 20-fold greater potency than the related compound Anordrin, while Dinordrin II exhibits considerably lower activity. These compounds are utilized in endocrine research to investigate steroid structure-activity relationships, particularly regarding estrogenic and antifertility mechanisms, with observed luteolytic effects including suppression of plasma estrogen and progesterone levels.