Open-label adjunctive topiramate in the treatment of unstable bipolar disorder.

OBJECTIVE To assess open-label adjunctive topiramate in the treatment of outpatients with unstable bipolar disorder (BD). METHOD Outpatients with DSM-IV-defined BD (I or II) exhibiting mood instability were enrolled in this 16-week, open-label, multicentre study. Topiramate was added to existing mood stabilizers and other psychotropic treatments. The primary effectiveness measure was the Clinical Global Impression of Severity (CGI-S) scale; other scales included the Young Mania Rating Scale (YMRS) and the Montgomery-Asberg Depression Rating Scale (MADRS). Safety assessments included monitoring adverse events, measuring tremor, monitoring vital signs and weight, and laboratory indices. We also evaluated patient satisfaction with treatment. RESULTS A total of 109 patients were enrolled. Intent-to-treat analysis showed significant improvement from baseline in the CGI-S, YMRS, and MADRS, starting at Week 2 (P < 0.001), with further accrual of benefit between Week 2 and Week 16 (P < 0.001). The mean modal dosage of topiramate during the stable dosing period was 180 mg daily. There was a mean 1.8 kg decrease in patient weight from topiramate initiation to Week 16 (P < 0.001). Topiramate was well tolerated by most patients; 11% withdrew from the study owing to adverse events. We noted a significant reduction in the mean severity score for preexisting tremor by Week 8 of treatment (P < 0.005); no notable changes in vital signs were observed. At Week 16, 50% of the patients were "completely satisfied" with topiramate treatment. CONCLUSIONS Adjunctive topiramate treatment can reduce the severity of manic and depressive symptoms, as well as reducing tremor and weight in outpatients with BD I or II.