Open-label adjunctive topiramate in the treatment of bipolar disorders

To preliminarily explore the spectrum of effectiveness and tolerability of the new antiepileptic drug topiramate in bipolar disorder, we evaluated the response of 56 bipolar outpatients in the Stanley Foundation Bipolar Outcome Network (SFBN) who had been treated with adjunctive topiramate in an open-label, naturalistic fashion.

In this case series, response to topiramate was assessed every 2 weeks for the first 3 months according to standard ratings in the SFBN, and monthly thereafter while patients remained on topiramate. Patients' weights, body mass indices (BMIs), and side effects were also assessed.

Of the 54 patients who completed at least 2 weeks of open-label, add-on topiramate treatment, 30 had manic, mixed, or cycling symptoms, 11 had depressed symptoms, and 13 were relatively euthymic at the time topiramate was begun. Patients who had been initially treated for manic symptoms displayed significant reductions in standard ratings scores after 4 weeks, after 10 weeks, and at the last evaluation. Those patients who were initially depressed or treated while euthymic showed no significant changes. Patients as a group displayed significant decreases in weight and BMI from topiramate initiation to week 4, to week 10, and to the last evaluation. The most common adverse side effects were neurologic and gastrointestinal.

These preliminary open observations of adjunctive topiramate treatment suggest that it may have antimanic or anticycling effects in some patients with bipolar disorder, and may be associated with appetite suppression and weight loss that is often viewed as beneficial by the patient and clinician. Controlled studies of topiramate's acute and long-term efficacy and side effects in bipolar disorder appear warranted.