zonampanel zonampanel zonampanel (inn, code name ym872) is a quinoxalinedione derivative drug and competitive antagonist of the ampa receptor which was being investigated by yamanouchi/astellas pharma as a neuroprotective drug for the treatment of ischemic stroke but never completed clinical trials. in clinical trials, zonampanel produced severe side effects including hallucinations, agitation, and catatonia in patients, resulting in early termination of the trials. zonampanelclinical dataatc codenoneidentifiers iupac name acetic acid cas number210245-80-0pubchem cid148200chemspider130649unii9x33544ilscomptox dashboard (epa)dtxsid50175232 chemical and physical dataformulac13h9n5o6molar mass331.244 g·mol−13d model (jsmol)interactive image smiles c1cn(cn1)c2cc3c(cc2(=o))c(=o)c(=o)n3cc(=o)o inchi inchi=1s/c13h9n5o6/c19-11(20)5-17-8-4-9(16-2-1-14-6-16)10(18(23)24)3-7(8)15-12(21)13(17)22/h1-4,6h,5h2,(h,15,21)(h,19,20)key:spxyhzrwprqlns-uhfffaoysa-n