Study of Safety & Tolerability of OPC-34712 as Adjunctive Therapy in Treatment of Adult Patients With Major Depressive Disorder

Inclusion Criteria:

• Male or female subjects between 18 and 65 years of age, with a diagnosis of a singleor recurrent, non-psychotic episode of major depressive disorder, as defined byDSM-IV-TR criteria and confirmed by the Mini International Neuropsychiatric Interview (M.I.N.I.) which is equal to or greater than 8 weeks in duration.

• Subjects must currently be taking allowable antidepressant therapy at an adequate dosefor a minimum of six weeks by the end of the screening period (ie at the time of theBaseline visit).

• Subjects must report a history for the current depressive episode of an inadequateresponse to at least one and no more than four adequate antidepressant treatments.

Exclusion Criteria:

• Females who are breast-feeding and/or who have a positive pregnancy test result priorto receiving study drug.

• Subjects who report an inadequate response to more than three adequate trials ofantidepressant treatments during current depressive episode at a therapeutic dose foran adequate duration.

• Subjects with a current Axis I (DSM-IV-TR) diagnosis of: Delirium, dementia,amnesticor other cognitive disorder Schizophrenia, schizoaffective disorder, or otherpsychotic disorder Bipolar I or II disorder, eating disorder (including anorexianervosa or bulimia), obsessive compulsive disorder, panic disorder, post-traumaticstress disorder.

• Subjects with a clinically significant current Axis II (DSM-IV-TR) diagnosis ofborderline, antisocial, paranoid, schizoid, schizotypal or histrionic personalitydisorder.