Study Of The Effects Of A New Antidepressant Therapy In Patients With Major Depressive Disorder (MDD)

Inclusion criteria: * Primary diagnosis of Major depressive Disorder as defined in DSM-IV. * Capable of giving informed consent and willing to comply with the study requirements. * Women of childbearing potential must agree to one of a number of defined acceptable methods of birth control. Exclusion Criteria: * Primary diagnosis within the past 6 months of another Axis 1 disorder such as an anxiety disorder. * Use of medications for a psychiatric condition including herbals in the past 2-12 weeks according to medication type. * Subjects who, in the investigator's judgement, pose a current, serious suicidal or homicidal risk or have made a suicide attempt within the past 6 months. * Subjects who currently meet or who met within 6 months prior to screening DSM-IV criteria for substance abuse or subjects who currently meet or who met within 6 months prior to screening DSM-IV criteria for substance dependence (other than nicotine). * Significantly abnormal blood or urine laboratory tests or electrocardiogram (ECG).