Naltrexone Augmentation of Risperidone in Treatment of Schizophrenia Symptoms: a Randomized Placebo-Controlled Study

Objectives: To investigate the hypothesis that naltrexone augmentation of antipsychotics may show beneficial effects on symptoms of schizophrenia. Method: Sixty nine participants were randomized to two groups for a 12-weeks trial. Positive and negative symptoms of schizophrenia were assessed with the Scale for Assessment of Positive Symptoms (SAPS) and the Scale for Assessment of Negative Symptoms (SANS). Subjects received naltrexone100 mg or placebo augmented to risperidone in a double-blind method. All participants were under treatment of risperidone 4mg as a primary antipsychotic treatment. Results: Patients in both treatment groups showed a reduction in their overall mean SAPS & SANS score at all measurement points compared with baseline scores, but there was significant difference between the 2 groups (p<0.05). Mean SANS score decreased 8.20 and 4.23 in Naltrexone and placebo group respectively after trial course (p<0.05). SAPS score decreased 7.67 and 4.63 in Naltrexone and placebo group respectively after trial course (p<0.05). Discussion: In this study the augmentation of naltrexone to risperidone showed a significant reduction of schizophrenia symptoms according to SAPS & SANS scores. Further studies to evaluate the efficacy of Naltrexone augmentation to atypical antipsychotic are warranted.