Metapristone

Metapristone
Clinical data
Other names	RU-42633; Desmethylmifepristone; 17β-Hydroxy-11β-[4-(methylamino)phenyl]-17α-(prop-1-yn-1-yl)estra-4,9-dien-3-one
Identifiers
	IUPAC name (8S,11R,13S,14S,17S)-17-hydroxy-13-methyl-11-[4-(methylamino)phenyl]-17-prop-1-ynyl-1,2,6,7,8,11,12,14,15,16-decahydrocyclopenta[a]phenanthren-3-one;
CAS Number	104004-96-8;
PubChem CID	10070462;
ChemSpider	8246002;
UNII	K1P8OGJ86J;
ChEMBL	ChEMBL1608;
CompTox Dashboard (EPA)	DTXSID60146216 ;
Chemical and physical data
Formula	C28H33NO2
Molar mass	415.577 g·mol−1
3D model (JSmol)	Interactive image;
	SMILES CC#C[C@@]1(CC[C@@H]2[C@@]1(C[C@@H](C3=C4CCC(=O)C=C4CC[C@@H]23)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/s1; Key:IBLXOBHABOVXDY-WKWWZUSTSA-N;

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.^[1]^[2]^[3]^[4] It is formed from mifepristone in the liver by the enzyme CYP3A4 via monodemethylation, and circulates at concentrations higher than those of mifepristone.^[1]^[5] The metabolite retains partial but considerable affinity for the progesterone receptor (PR) and the glucocorticoid receptor (GR) (RBATooltip relative binding affinity = 21% and 61% of that of mifepristone for the human forms of these receptors, respectively).^[6]^[1] On the basis of actions that are apparently independent of its hormonal activity, metapristone is being researched as a potential cancer metastatic chemopreventive agent.^[2]^[3]^[4]