Relugolix is a novel, non-peptide, orally active gonadotropin-releasing hormone (GnRH) antagonist with IC50 of 0.33 nM in the presence of 40% fetal bovine serum, TAK-385 possesses higher affinity and potent antagonistic activity compared with TAK-013.target: GnRH [1]IC50: 0.33 nM [1]In vivo: In female knock-in mice, twice-daily oral administration of TAK-385 (100mg/kg) induces constant diestrous phases within the first week, decreases the uterus weight to ovariectomized levels and downregulated GnRH receptor mRNA in the pituitary after 4 weeks.[2]

[1]. MacLean DB et al. Medical Castration Using the Investigational Oral GnRH Antagonist TAK-385 (Relugolix): Phase 1 Study in Healthy Males. J Clin Endocrinol Metab. 2015 Dec;100(12):4579-87. [2]. Nakata D et al. Suppression of the hypothalamic-pituitary-gonadal axis by TAK-385 (relugolix), a novel, investigational, orally active, small molecule gonadotropin-releasing hormone (GnRH) antagonist: studies in human GnRH receptor knock-in mice. Eur J Ph