Clinical data Synonyms 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
[(8 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
ChemSpider Chemical and physical data
Formula C 24 H 29 F O 4
Molar mass 400.49 g/mol g·mol −1 3D model (
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
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-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
The drug showed no
estrogenic activity in animals, but did show some
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.
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.
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.