nilestriol nilestriol nilestriol (inn) (brand name wei ni an; developmental code name ly-49825), also known as nylestriol (usan, ban), is a synthetic estrogen which was patented in 1971 and is marketed in china. it is the 3-cyclopentyl ether of ethinylestriol, and is also known as ethinylestriol cyclopentyl ether (ee3cpe). nilestriol is a prodrug of ethinylestriol, and is a more potent estrogen in comparison. it is described as a slowly-metabolized, long-acting estrogen and derivative of estriol. nilestriol was assessed in combination with levonorgestrel for the potential treatment of postmenopausal osteoporosis, but this formulation ultimately was not marketed. nilestriolclinical datatrade nameswei ni another namesnylestriol; ly-49825; ethinylestriol cyclopentyl ether; ee3cpe; 17α-ethynylestriol 3-cyclopentyl etherroutes ofadministrationby mouthdrug classestrogen; estrogen etheridentifiers iupac name (8r,9s,13s,14s,16r,17r)-3-cyclopentyloxy-17-ethynyl-13-methyl-7,8,9,11,12,14,15,16-octahydro-6h-cyclopentaphenanthrene-16,17-diol cas number39791-20-3pubchem cid38346chemspider35146unii7ja3b3ialukeggd05212chemblchembl2104468chemical and physical dataformulac25h32o3molar mass380.528 g·mol−13d model (jsmol)interactive image smiles c12cc3(1c(2(c#c)o)o)ccc4=c3c=cc(=c4)oc5cccc5 inchi inchi=1s/c25h32o3/c1-3-25(27)23(26)15-22-21-10-8-16-14-18(28-17-6-4-5-7-17)9-11-19(16)20(21)12-13-24(22,25)2/h1,9,11,14,17,20-23,26-27h,4-8,10,12-13,15h2,2h3/t20-,21-,22+,23-,24+,25+/m1/s1key:chzjrgndjljlaw-riqjqhkosa-n