Primary Objective:

- To evaluate the effects of two fixed doses of SSR149415 (250 mg bid and 100 mg bid) on hypothalamic-pituitary-adrenal axis function in patients with major depressive disorder.

Secondary Objectives:

• To evaluate the tolerability and safety of SSR149415 in patients with major depressive disorder.
• To evaluate the efficacy of two fixed doses of SSR149415 compared to placebo in patients with major depressive disorder.
• To evaluate plasma concentrations of SSR149415.

The study consisted of three segments (A, B and C). Segment A was a 1 to 4-week, drug-free, screening and baseline period. Segment B was a 4-week, double-blind period. After the last dose of double-blind study medication in Segment B, all patients had to enter Segment C, a 1-week drug-free, follow-up period.

The total study duration for one patient participating in all segments of the study was 6 weeks.

Inclusion criteria :

• Diagnosis of major depressive disorder as defined by the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition-Text Revision (DSM-IV-TR) and the Mini International Neuropsychiatric Interview (MINI) criteria.

Exclusion criteria:

• Outpatients unwilling to be hospitalized a total of 6 nights and 8 days.
• Total score of less than 21 (<21) on the 17-item Hamilton Depression Rating Scale (HAM-D) at Visit 1 (Day -7) or Visit 5 (Day -1).
• Patients whose current depressive episode is diagnosed with psychotic features, catatonic features, seasonal pattern or post-partum onset or is secondary to a general medical disorder.
• Patients with alcohol dependence or abuse or substance dependence or abuse in the past 12 months according to the MINI, except nicotine or caffeine dependence.
• Patients who have used the following prior to entry into Segment B: any antipsychotic within 3 months; fluoxetine within 1 month; any monoamine oxidase inhibitor (MAOI) within 2 weeks; any other antidepressant, anxiolytic, sedative-hypnotic, or mood-stabilizer (lithium, anticonvulsants) within 7 days except permitted concomitant medications
• The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.