Adjunctive topiramate in the maintenance treatment of bipolar disorders: an open-label study

A considerable number of patients with bipolar disorder fail to respond completely to mood stabilizers. The anti-epileptic topiramate shares some pharmacological actions with carbamazepine and valproate. We therefore explored the efficacy and tolerability of topiramate in the prophylaxis of bipolar disorder.

Fifty-six patients receiving outpatient treatment for bipolar affective disorder who had been on mood stabilizers, and had relapsed at least once in the past 12 months, were treated with topiramate in an add-on design and were evaluated for 1 year. Patients were assessed biweekly for the first 3 months and every month thereafter.

Fifty out of 56 patients completed the 1-year study, which indicated that adjunctive topiramate was associated with a significant reduction of new manic and depressive episodes compared to the past 12 months. The most common adverse effects were reduced appetite, fatigue and somnolence.

This was an open-label, uncontrolled study involving retrospective evaluation of episodes prior to the initiation of treatment, and the use of more than one mood stabilizer in a few patients. However, these preliminary observations of adjunctive topiramate as a maintenance treatment encourage further investigations, especially with controlled trials, for its long-term effect.