Safety and Pharmacodynamic Study of ABT-436 in Major Depressive Disorder

This is a multiple-dose study to assess the safety and pharmacology of ABT-436 in physically healthy subjects with mild to moderate depressive symptoms who are not taking any antidepressant medication. Efficacy for treatment of depressive symptoms is not a goal of this study. Fifty subjects will receive study drug for seven days. Thirty subjects will receive ABT-436 and twenty subjects will receive placebo. Blood, urine and saliva samples will be obtained, both before and during study drug administration, to measure ABT-436 pharmacology. Safety will be assessed throughout the study, including at two follow-up visits after completion of study drug administration.

Inclusion criteria

• Age between 18 to 55 years, inclusive. 2. Body Mass Index is 20 to 35 kg/m2, inclusive. 3. A primary Diagnostic and Statistical Manual of Mental Disorders - Fourth Edition, Text Revision (DSM-IV-TR) diagnosis of major depressive disorder.

• Mild-to-moderate depressive symptoms at Screening. 5. A condition of general good physical health. Exclusion Criteria

• Pregnant or breast-feeding female.
• Use of any medication within 4 weeks prior to Day -2, unless the dose has been stable for 4 weeks, no dose change is anticipated during the study, and the medication is specifically allowed for this study, OR prior as needed (PRN) use of the medication is specifically allowed for this study.
• Use of fluoxetine or aripiprazole within 8 weeks prior to Day -2.
• Positive screen for drugs of abuse/alcohol, recent history of drug/alcohol abuse or smoking.
• A current or past history of major depressive disorder with psychotic features, bipolar disorder, schizophrenia or other psychotic disorder, mental retardation, or mental disorder due to a general medical condition.