Clinical Trial of Felbamate for Treatment-Resistant Bipolar Depression

INCLUSION CRITERIA: Subjects may be included in the study only if they meet all of the following criteria: Male or female subjects, 18 years or older. Female subjects of childbearing potential must be using a medically accepted means of contraception. Each subject must have a level of understanding sufficient to agree to all tests and examinations required by the protocol. Each subject must understand the nature of the study and must sign an informed consent document. Subjects must fulfill the criteria for Bipolar I or II disorder depressed without psychotic features as defined in DSM-IV based on clinical assessment and confirmed by structured diagnostic interview SCID-P. Subjects must have an initial score at Visit 1 and Visit 2 of a least 20 on the MADRS. Subjects must not have a decrease in the total score of MADRS of greater than or equal to 20% during washout (between Visits 1 and 2). Meet criteria for treatment refractory depression operationally defined in appendix using the modified Antidepressant Treatment History Form (ATHF). Subjects with a partial response to lithium may continue to take the medication during the trial; otherwise, subjects will proceed with a washout and monotherapy trial with felbamate. Current major depressive episode of no less than 3 months. EXCLUSION CRITERIA: Subjects will be excluded from the study for any of the following reasons: Currently taking a protocol disallowed agent that is effective and specifically necessary for that individual for the recurrence of mania. Participation in a clinical trial of another investigational drug within 1 month (30 days) prior to study entry (Visit 1). Female subjects who are either pregnant or nursing. Serious, unstable illnesses including hepatic, renal, gastroenterologic, respiratory, cardiovascular (including ischemic heart disease), endocrinologic, neurologic, immunologic or hematologic disease. History of hepatic dysfunction. Subjects with uncorrected hypothyroidism or hyperthyroidism. Subjects with one or more seizures without a clear and resolved etiology. Documented history of hypersensitivity to felbamate, meprobamate or other carbamates. DSM-IV substance abuse (except nicotine and caffeine) within the past 30 days and substance dependence within the past 3 months or positive results for illicit drugs at prestudy drug screen. Subjects with a rapid cycling course of illness (defined as 4 affective episodes in the previous year) in the past 12-months. Treatment with an injectable depot neuroleptic within less than one dosing interval between depot neuroleptic injections prior to Visit 2. Treatment with a reversible monoamine oxidase inhibitor, guanethidine, or guanadrel within 1 week prior to Visit 2. Treatment with fluoxetine within 4 weeks prior to Visit 2. Treatment with any other concomitant medication with primarily CNS activity, other than specified in Appendix A of protocol. Treatment with clozapine or ECT within 12 weeks prior to Visit 2. Current diagnosis of schizophrenia or other psychotic disorder as defined in the DSM-IV. History of hypersensitivity or idiosyncratic reactions (e.g., rash, hepatitis, or cytopenia) to any drug. History or current clinically significant immune disorders including autoimmune disease (e.g., systemic lupus erythematosus (SLE), autoimmune hemolytic anemia, autoimmune liver disease) or a history of any blood dyscrasia. Thus a history of anemias or cytopenias that were not obviously related to a limited benign process (e.g., anemia related to menstrual bleeding) will be reason for exclusion. Consultation with hematology will be used for help with any 'gray area' cases. Judged clinically to be at serious suicidal risk, with a score of 3 or more on item 3 of the HAMD.