Background: A series of open studies suggests that topiramate has efficacy in bipolar disorder. To further investigate the potential value of topiramate as an antimanic agent, we conducted an open trial in 11 manic patients.

Method: Eleven patients with bipolar I disorder with an acute manic episode (DSM-IV) were treated with a mood stabilizer and/or antipsychotics in sufficient and fixed doses. All had a Young Mania Rating Scale (YMRS) score of at least 24 (mean ± SD = 33.5 ± 8.1). Topiramate was added after stable plasma levels of concomitant mood stabilizers had been reached and was titrated within 1 week to a final dose in the range of 25 to 200 mg/day, depending on clinical efficacy and tolerability. Topiramate was discontinued after 10 days, while concomitant medication remained unchanged. After 5 days, topiramate was reintroduced at similar or increased dosages for another 7 days. Patients were assessed with the YMRS; the Clinical Global Impressions scale version for bipolar patients; and the 21-item Hamilton Rating Scale for Depression.

Results: Seven of the 11 patients initially showed a good antimanic response with > 50% reduction in YMRS score. One patient showed psychotic features following rapid increase in topiramate dosage and dropped out on day 10. After discontinuation of topiramate, 7 of the remaining 10 patients worsened (increase of >= 25% in YMRS score), 2 remained stable, and 1 discontinued follow-up after good recovery. After reintroducing topiramate, all patients improved again within a week, with 8 of 9 meeting the responder criterion of >= 50% YMRS score reduction when comparing baseline values with those of day 22. With the exception of the patient who developed psychosis, topiramate was well tolerated. Concomitant medication did not interfere with plasma levels of drug, except for carbamazepine level in 1 patient.

Conclusion: The antimanic response among patients in this study appears reproducibly linked to the addition of topiramate.