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.