• Change from baseline to Day 21 for the Young Mania Rating Scale (YMRS) total score.
  

• Change from baseline to Day 21 for scores on MADRS, BPRS, CGI, and GAS; response to treatment, indicated by not any longer meeting DSM-IV criteria for manic/mixed episode.
  

This is a randomized, double-blind, placebo-controlled study to evaluate the effectiveness of two dose levels of topiramate (400 and 600 milligrams/day) compared with placebo in the treatment of acute manic or mixed episodes in patients with Bipolar I Disorder. The trial consists of 3 phases: a screening period; double-blind treatment for 12 weeks; and an optional open-label period of at least 6 months. Assessment of effectiveness include change from baseline to Day 21 for the Young Mania Rating Scale (YMRS) total score. Also included during the 12 week study are the Global Assessment Scale (GAS), Montgomery-Åsberg Depression Rating Scale (MADRS), Brief Psychiatric Rating Scale (BPRS), Clinical Global Impressions (CGI), and health-related quality of life measures at specified time intervals. Safety assessments include evaluation of adverse events, rate of withdrawal from the study due to adverse events, and vital signs (blood pressure and pulse) throughout the study, as well as changes in clinical laboratory tests (hematology, biochemistry, urinalysis), electrocardiograms (ECGs), and physical examinations at specified times. The study hypothesis is that the change from baseline in Young Mania Rating Scale (YMSR) total score at Day 21 will be significantly better for the topiramate groups than for the placebo group. Topiramate tablets (50 or 100 milligrams) or placebo, beginning at 50mg daily and increasing over the first week to a maximum of 400mg/day or 600mg/day, depending on study group. Maximum dosage continues up to 12 weeks. Dosage can be decreased or increased at investigator's discretion.