The purpose of this study is to determine the safety and efficacy of topiramate in adolescents with manic or mixed episodes of Bipolar I Disorder.

This is a 4-week study to evaluate the safety and effectiveness of topiramate compared to placebo in the treatment of Bipolar I Disorder with an optional 6-month open-label (OL) extension for qualified patients following completion of the study. On Days 1-28 patients will receive placebo or topiramate 2x/day by mouth except for the 1st and last doses which will be a single evening dose and a single morning dose, respectively. Study drug will be titrated in 100-mg increments to 400 mg/day and patients maintained on a stable dose through Day 28. During the OL extension phase, topiramate will be titrated over 5 days to 200 mg/day. After Day 7, topiramate may be tapered down to 100 mg/day or up to 600 mg/day, as clinically indicated.

Inclusion Criteria:

• DSM-IV diagnosis of Bipolar I Disorder (confirmed by the Kiddie-Schedule for Affective Disorders and Schizophrenia-Present and Lifetime version [K-SADS-P/L])
• YMRS score greater than or equal to 20
• General good health as determined by medical history, physical examination, and laboratory evaluations
• Ability to swallow tablets
• Patient's parent or guardian must be fully capable of monitoring the patient's disease process and compliance to treatment
• Parent(s) or legal guardian(s) must read and sign the informed consent form after the nature of the study has been fully explained and assent must be obtained from patients

Exclusion Criteria:

• DSM-IV Axis I disorder diagnoses of autistic disorder, schizophrenia, schizoaffective disorder, or other psychotic disorders not otherwise specified (NOS)
• DSM-IV diagnosis of alcohol or substance dependence, with the exception of nicotine or caffeine dependence, within the 3 months prior to baseline. Acute or intermittent substance abuse prior to screening will not be exclusionary, depending upon the clinical judgment of the investigator
• Chronic antidepressant treatment within 4 weeks of randomization (5 weeks for fluoxetine), use of psychostimulants in the 7 days prior to baseline, use of any other psychotropic medications within 3 days or 5 half-lives, whichever is less, prior to baseline, or requirement for treatment with other psychotropic drugs on an ongoing basis
• Weight less than 33 kg or current or past history of anorexia nervosa
• Serious or unstable medical or neurological conditions