metapristone metapristone metapristone (developmental code name ru-42633; also known as desmethylmifepristone) is the major metabolite of mifepristone (ru-486, ru-38486) and a selective progesterone receptor modulator (sprm) which itself was never marketed. it is formed from mifepristone in the liver by the enzyme cyp3a4 via monodemethylation, and circulates at concentrations higher than those of mifepristone. the metabolite retains partial but considerable affinity for the progesterone receptor (pr) and the glucocorticoid receptor (gr) (rba = 21% and 61% of that of mifepristone for the human forms of these receptors, respectively). on the basis of actions that are apparently independent of its hormonal activity, metapristone is being researched as a potential cancer metastatic chemopreventive agent. metapristoneclinical dataother namesru-42633; desmethylmifepristone; 17β-hydroxy-11β--17α-(prop-1-yn-1-yl)estra-4,9-dien-3-oneidentifiers iupac name (8s,11r,13s,14s,17s)-17-hydroxy-13-methyl-11--17-prop-1-ynyl-1,2,6,7,8,11,12,14,15,16-decahydrocyclopentaphenanthren-3-one cas number104004-96-8pubchem cid10070462chemspider8246002uniik1p8ogj86jchemblchembl1608comptox dashboard (epa)dtxsid60146216 chemical and physical dataformulac28h33no2molar mass415.577 g·mol−13d model (jsmol)interactive image smiles cc#c1(cc21(c(c3=c4ccc(=o)c=c4cc23)c5=cc=c(c=c5)nc)c)o inchi inchi=1s/c28h33no2/c1-4-14-28(31)15-13-25-23-11-7-19-16-21(30)10-12-22(19)26(23)24(17-27(25,28)2)18-5-8-20(29-3)9-6-18/h5-6,8-9,16,23-25,29,31h,7,10-13,15,17h2,1-3h3/t23-,24+,25-,27-,28-/m0/s1key:iblxobhabovxdy-wkwwzustsa-n