A multicenter, 10-week study to evaluate the efficacy and safety of Sustained-Release Desvenlafaxine Hydrochloride versus Sustained-Release venlafaxine Hydrochloride in adult with major depressive disorder.

Inclusion Criteria:

• Adult with primary diagnosis of Major Depressive Disorder
• Aged from 18 years to 65 years
• A primary diagnosis of Major Depressive Disorder based on the criteria in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM- IV-TR), single or recurrent episode, without psychotic features
• Hamilton Psychiatric Rating Scale for Depression (HAM-D 17) total score of ≧ 20
• Clinical Global Impressions Scale-Severity (CGI-S) score of ≧4

Exclusion Criteria:

• Known hypersensitivity to desvenlafaxine or venlafaxine
• Significant risk of suicide based on clinical judgment
• Women who were pregnant,breast-feeding,or planning to become pregnant during study
• Had a history of seizure disorder
• History or current evidence of gastrointestinal disease known to interfere with the absorption or excretion of drugs or a history of surgery known to interfere with the absorption or excretion of drugs
• Any unstable hepatic, renal, pulmonary, cardiovascular, ophthalmologic, neurologic, or other severe acute or chronic medical or psychiatric condition or laboratory abnormality that may increase the risk associated with study participation or investigational product administration or may interfere with the interpretation of study results
• Cancer