posovolone posovolone posovolone (developmental code name co 134444) is a synthetic neurosteroid which was under development as a sedative/hypnotic medication for the treatment of insomnia. it is orally active and acts as a gabaa receptor positive allosteric modulator. in animals, posovolone shows anticonvulsant, anxiolytic-like, ataxic, and sleep-promoting effects and appeared to produce effects similar to those of pregnanolone. development of the agent was started by 1999 and appears to have been discontinued by 2007. in 2021, an inn was registered for posovolone with the descriptor of "antidepressant". posovolone was originally developed by purdue pharma. posovoloneclinical dataother namesco-134444; co 134444; v-134444; 3β-hydroxy-21-(1h-imidazol-1-yl)-3α-(methoxymethyl)-5α-pregnan-20-oneidentifiers iupac name 1-phenanthren-17-yl]-2-imidazol-1-ylethanone cas number256955-84-7pubchem cid9802683chemspider7978445unii1ga9jvo9zachemical and physical dataformulac26h40n2o3molar mass428.617 g·mol−13d model (jsmol)interactive image smiles c12cc(c1cc32cc4(3cc4c(=o)cn5c=cn=c5)c)(coc)o inchi inchi=1s/c26h40n2o3/c1-24-10-11-26(30,16-31-3)14-18(24)4-5-19-20-6-7-22(25(20,2)9-8-21(19)24)23(29)15-28-13-12-27-17-28/h12-13,17-22,30h,4-11,14-16h2,1-3h3/t18-,19-,20-,21-,22+,24-,25-,26+/m0/s1key:brvgkznqwcqktc-mvcivnjcsa-n