- Medically healthy males or females aged 18-65 (inclusive).
- Patients must have a primary current diagnosis of MDD without psychotic features.
- Patients must be receiving ongoing antidepressant therapy at the time of screening.
Duration of the current episode of MDD must be at least 8 weeks prior to enrollment
without adequate response to treatment.
- Patients with other psychiatric disorders.
- Patients who use tobacco products.
- Alcohol or substance abuse or dependence.
- Treatment with a monoamine oxidase inhibitor within 10 weeks of enrollment.
- Pregnancy or breastfeeding.
- Clinically significant abnormalities on laboratory tests, electrocardiogram, or
physical or neurologic examination.