Topiramate Versus Placebo as add-on Treatment in Patients With Bipolar Disorder in the Outpatient Setting

The purpose of this study is to assess the efficacy and safety of adding topiramate as compared to placebo to the medications a patient with bipolar disorder is already taking (lithium or valproate) to see if adding topiramate will better control the patient's manic symptoms.

Many patients with bipolar disorder (manic-depressive illness) require more than one medication to control their symptoms. This is a 12-week, multicenter, randomized, double-blind, placebo-controlled, parallel-groupd study to evalute the efficacy and safety of topiramate versus placebo as add-on therapy to lithium or valproate for the treatment of bipolar 1 disorder as an outpatient setting. These patients must already be taking either lithium or valproate for at least 6 weeks before the first visit and have been on the same dose of the mood stabilizer for at least 2 weeks before the first visit. Paitents will be randomized to receive either placebo or topiramate, an anti-seizure medication not approved for the treatment of bipolar disorder, in addition to their lithium or valporate. The study consists of 56-day titration (topiramate will be titrated up to 400mg per day or the maximum tolerated dose), 28-day continuation period, and 7 days of follow-up to taper off the medication. The study hypothesis is that topiramate will be more effective than placebo in the treatment of mania in type 1 bipolar disorder patients as measured by the Young Mania Rating Scale (YMRS) and will be well tolerated. YMRS is a questionnaire consisting of 11 items designed to assess severity of mania symptoms. Patients will start taking topiramate 25 mg per day or placebo by mouth. Over the next 8 weeks, doses will be increased to up to 400 mg per day or to the maximum tolerated dose, whichever is lower. After the first 8 weeks, patients will stay at the established dose for the next 4 weeks.