Effect of a novel potential atypical antipsychotic drug, Y-931, in producing dystonia in Cebus monkeys

The effect of Y-931 (8-fluoro-12-(4-methylpiperazin-1-yl)-6H-[1]benzothieno[2,3-b][1,5]benzodiazepin e maleate), a novel potential atypical antipsychotic candidate, in producing dystonia in Cebus monkeys was investigated. Y-931 induced relatively weak dystonia in several observation periods at doses greater than 0.1 mg/kg, i.m. Although Y-931 significantly increased total dystonia scores (the sum of 15 to 360 min after injection) at doses greater than 0.5 mg/kg, i.m., the scores did not exceed 20, up to a dose of 1.0 mg/kg, i.m. and lacked a dose-response relationship. The present result suggests that Y-931 is predicted to have a low risk of extrapyramidal side effects.