lonaprisan lonaprisan lonaprisan (inn, usan) (developmental code names zk-230211, bay 86-5044, zk-pra) is a synthetic, steroidal antiprogestogen which was under development by bayer healthcare pharmaceuticals for the treatment of endometriosis, dysmenorrhea, and breast cancer but was discontinued. it is a potent and highly selective silent antagonist of the progesterone receptor (pr). the drug reached phase ii clinical trials prior to its discontinuation. lonaprisanclinical dataother nameszk-230211; bay 86-5044; zk-pra; 11β-(4-acetylphenyl)-17β-hydroxy-17α-(1,1,2,2,2-pentafluoroethyl)estra-4,9-dien-3-oneroutes ofadministrationoralidentifiers iupac name (8s,11r,13s,14s,17s)-11-(4-acetylphenyl)-17-hydroxy-13-methyl-17-(1,1,2,2,2-pentafluoroethyl)-1,2,6,7,8,11,12,14,15,16-decahydrocyclopentaphenanthren-3-one cas number211254-73-8pubchem cid6918548chemspider5293745uniif5z5el4d26keggd10016chemblchembl146032comptox dashboard (epa)dtxsid60893551 echa infocard100.190.674 chemical and physical dataformulac28h29f5o3molar mass508.529 g·mol−13d model (jsmol)interactive image smiles cc(=o)c1=cc=c(c=c1)2c3((cc3(c(c(f)(f)f)(f)f)o)4c2=c5ccc(=o)c=c5cc4)c inchi inchi=1s/c28h29f5o3/c1-15(34)16-3-5-17(6-4-16)22-14-25(2)23(11-12-26(25,36)27(29,30)28(31,32)33)21-9-7-18-13-19(35)8-10-20(18)24(21)22/h3-6,13,21-23,36h,7-12,14h2,1-2h3/t21-,22+,23-,25-,26-/m0/s1key:vhzpudnsvgrvmb-rxdlhwjpsa-n