Etonogestrel-d6 is deuterium labeled Etonogestrel. Etonogestrel (3-Oxodesogestrel), a biologically active metabolite of progestin Desogestrel, binds with high affinity to progesterone receptors and estrogen receptors in the target organs[1]. Etonogestrel induce FKBP51 mRNA and protein expression in cultured human endometrial stromal cells (HESCs)[2].