Major Depressive Disorder (MDD) With Mixed Features - Flexible Dose

Inclusion Criteria:

- Subject provides written informed consent and is willing and able to comply with the
protocol in the opinion of the Investigator.

- Subject is 18 to 75 years of age, inclusive.

- Subject has MDD (diagnosed by DSM-IV-TR, and confirmed by the Structured - Clinical
Interview for DSM-IV Disorders - Clinical Trial version [SCID-CT]).

- Subject is currently experiencing a major depressive episode (diagnosed by DSM IV TR;
at least 2 weeks in duration) AND two or three of the following manic symptoms
occurring on most days over at least the last 2 weeks (confirmed by the SCID-CT
modified for Study D1050304):

- Elevated, expansive mood

- Inflated self-esteem or grandiosity

- More talkative than usual or pressure to keep talking

- Flight of ideas or subjective experience that thoughts are racing

- Increase in energy or goal-directed activity (either socially, at work or
school, or sexually)

- Increased or excessive involvement in activities that have a high potential for
painful consequences (e.g., engaging in unrestrained buying sprees, sexual
indiscretions, or foolish business investments)

- Decreased need for sleep (feeling rested despite sleeping less than usual; to be
contrasted from insomnia)

Exclusion Criteria:

- Subject has Axis I or Axis II diagnosis other than MDD that has been the primary
focus of treatment within the 3 months prior to screening.

- Subject answers "yes" to "Suicidal Ideation" Item 4 or 5 on the C-SSRS (at time of
evaluation) at screening or baseline visit.

- Subject has attempted suicide within the past 3 months.

- Subject has a lifetime history of any bipolar I manic or mixed manic episode.

- Subject has any abnormal laboratory parameter at screening that indicates a
clinically significant medical condition as determined by the Investigator.