Background: This study was carried out to evaluate the efficacy, tolerability, and safety of gabapentin as an adjunctive treatment in patients with bipolar or schizoaffective disorder with manic or hypomanic symptoms.
Method: Twenty-five patients fulfilling DSM-IV diagnostic criteria for bipolar I disorder or schizoaffective disorder underwent a 16-week, open-trial treatment with gabapentin. Symptom severity was measured using the Clinical Global Impressions scale (CGI) and the Brief Psychiatric Rating Scale (BPRS). Baseline scores and final scores were compared by using the Student t test and the Friedman range variance analysis.
Results: Twenty-two patients (88%) completed the 16 weeks of treatment with gabapentin; 19 (76%) had a positive response as measured by changes in CGI and BPRS scores. The mean dose was 1440 mg/day. The only side effect observed was oversedation, which decreased with continuing treatment.
Conclusion: Gabapentin was effective in the treatment of mania and hypomania in patients with bipolar and schizoaffective disorders. If confirmed in controlled studies, these findings suggest that gabapentin represents a well-tolerated, rapidly acting antimanic agent.