Improved P50 auditory gating with ondansetron in medicated schizophrenia patients

Objective: Most schizophrenia patients have a deficit in auditory sensory gating, which appears to be mediated by the alpha-7 nicotinic receptor, that is not improved with conventional antipsychotic treatment. This study examined the effects of ondansetron, a highly selective 5-HT3 antagonist, on the P50 auditory evoked potential. Method: Eight medicated outpatients with schizophrenia were given either ondansetron ( 16 mg) or placebo in a double-blind, placebo-controlled design. Evoked potentials were recorded at baseline and 1 hour, 2 hours, and 3 hours after receipt of drug. Results: There was a highly significant improvement in P50 gating after ondansetron treatment. The maximal treatment difference was at 2 hours posttreatment ( ondansetron: mean= 41.4%, SD= 39.7%; placebo: mean= 80.2%, SD= 21.3%). Conclusions: Ondansetron significantly enhanced P50 auditory gating in schizophrenia patients treated with typical antipsychotics.