DU-41165 Other names 6-Fluoro-16-methylene-17α-acetoxy-δ 6-retroprogesterone; 6-Fluoro-16-methylene-17α-hydroxy-9β,10α-pregna-4,6-diene-3,20-dione 17α-acetate; 6-Fluoro-16-methylene-3,20-dioxo-9β,10α-pregna-4,6-dien-17α-yl acetate Routes of administration By mouth Drug class Progestin; Progestogen
R,9 R,10 S,13 S,14 S,17 R)-17-Acetyl-6-fluoro-10,13-dimethyl-16-methylidene-3-oxo-1,2,8,9,11,12,14,15-octahydrocyclopenta[ a]phenanthren-17-yl] acetate CAS Number PubChem CID ChemSpider CompTox Dashboard ( EPA) Formula C 24 H 29 F O 4 Molar mass g·mol 400.490 −1 3D model ( JSmol)
DU-41165, also known as 6-fluoro-16-methylene-17α-acetoxy-δ, is a 6-retroprogesterone progestin which was developed by Philips-Duphar in the 1970s and was never marketed.  It is a combined  derivative of 17α-hydroxyprogesterone and retroprogesterone.  The drug shows extremely high  potency as a progestogen in animals. It has been found to possess 158% of the  relative binding affinity of promegestone for the progesterone receptor expressed in rat uterus (relative to 74% for the closely related progestin DU-41164). DU-41165 also showed 28% of the affinity of  RU-28362 for the glucocorticoid receptor expressed in rat liver, but no affinity for the mineralocorticoid receptor expressed in rat kidney (<0.003% of that of RU-26752). The drug showed no  androgenic, anabolic, or estrogenic activity in animals, but did show some antiandrogenic and glucocorticoid activity at high doses. Although highly potent in animals, DU-41165 produced little or no progestogenic effect at dosages of 50 and 200 µg/day in women, suggesting major species differences.  DU-41165 has been studied as a potential  photoaffinity label for the progesterone receptor.
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Morsink L, de Wachter AM, Brenner P, Cekan SZ, Guerrero R, Hagenfeldt K, Diczfalusy E (May 1976). "Endocrine effects of two new retro-steroids in animal models and in women". Acta Endocrinol. 82 (1): 193–212. doi: 10.1530/acta.0.0820193. PMID 57688.
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Pinney KG, Carlson KE, Katzenellenbogen JA (February 1990). "[3H]DU41165: a high affinity ligand and novel photoaffinity labeling reagent for the progesterone receptor". J. Steroid Biochem. 35 (2): 179–89. doi: 10.1016/0022-4731(90)90272-T. PMID 2308335.