panamesine panamesine panamesine (inn; developmental code name emd-57455) is a sigma receptor antagonist that was under development by merck as a potential antipsychotic for the treatment of schizophrenia in the 1990s but was never marketed. it is a selective antagonist of both sigma receptor subtypes, the σ1 and σ2 receptors (ic50 = 6 nm). in addition, the major metabolite of the drug, emd-59983, has high affinity for the sigma receptors (ic50 = 24 nm) and the dopamine d2 (ic50 = 23 nm) and d3 receptors, with potent antidopaminergic activity. panamesine reached phase ii clinical trials for schizophrenia prior to the discontinuation of its development. panamesineclinical dataother namesemd-57455pharmacokinetic datametabolitesemd-59983identifiers iupac name (5s)-5-methyl]-3-(4-methoxyphenyl)-1,3-oxazolidin-2-one cas number139225-22-2pubchem cid3047810unii023d9e916lchemblchembl45686comptox dashboard (epa)dtxsid00160971 chemical and physical dataformulac23h26n2o6molar mass426.469 g·mol−13d model (jsmol)interactive image smiles coc1=cc=c(c=c1)n2c(oc2=o)cn3ccc(cc3)(c4=cc5=c(c=c4)oco5)o inchi inchi=1s/c23h26n2o6/c1-28-18-5-3-17(4-6-18)25-14-19(31-22(25)26)13-24-10-8-23(27,9-11-24)16-2-7-20-21(12-16)30-15-29-20/h2-7,12,19,27h,8-11,13-15h2,1h3/t19-/m0/s1key:ninyzudvktukia-ibgzpjmesa-n