Acetaminophen as Adjuvant to Risperidone in Chronic Schizophrenia: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial.

Objective: Although the pathogenesis of schizophrenia is still uncertain, a variety of predisposing mechanisms have been implicated including inflammatory cascades. The present study was conducted to investigate the effectiveness of acetaminophen as a cyclooxygenase inhibitor in treating patients with schizophrenia. Method : A double-blind clinical trial was performed on 52 patients with chronic schizophrenia. Patients received risperidone (up to 6 mg/day) plus either acetaminophen (975mg/day) or placebo. Psychotic symptoms were assessed by the Positive and Negative Syndrome Scale (PANSS) at the onset of the trial, and at 2, 4, 6, and 8 weeks post therapy. Results: Compared to the placebo group, the acetaminophen group showed no significant difference in any subtypes of PANSS. Moreover, the side effect profiles of the 2treatment regimens were not significantly different. Conclusion: Acetaminophen adjuvant to risperidone showed no significant effect in ameliorating symptoms of schizophrenia. Trial Registration: The trial was registered at the Iranian Registry of Clinical Trials (registration number: IRCT201410251556N67).