• the change of HAMD-17 total score [ Time Frame: from the baseline to week 8 ] [ Designated as safety issue: No ]
  

• the change of MADRS total score [ Time Frame: from the baseline to week 8 ] [ Designated as safety issue: No ]
  
• the change of HAMA total score [ Time Frame: from the baseline to week 8 ] [ Designated as safety issue: No ]
  
• the clinical global impression (CGI),including CGI-I and CGI-S [ Time Frame: from the baseline to week 8 ] [ Designated as safety issue: No ]
  
• the change of VAS-PI [ Time Frame: from the baseline to Week 8 ] [ Designated as safety issue: No ]
  
• the change of Sheehan Disability Scale(SDS) [ Time Frame: from the baseline to Week 8 ] [ Designated as safety issue: No ]
  

This is a double-blind, parallel assignment, randomized and innovator controlled study. The subjects investigated are outpatients with major depressive disorder(MDD)according to DSM-IV from the Chinese population. The screening phase lasts for 1 week. The eligible patients enter the next randomized treatment phase. The fixed dose(generic escitalopram 10mg/d or Innovator Escitalopram(Lexapro®) 10mg/d) duration is 2 week. After the first 2 weeks, according to CGI and investigator's assessment the patients are administrated 2 different dose, one is previous dose 10mg/d, the other is high dose 20mg/d. In this study, total duration lasts for 8 weeks.

The efficacy and safety of Innovator Escitalopram(Lexapro®) in the treatment of patients with MDD have been confirmed by multiple double blind studies. This study is designed to evaluate the efficacy and safety of genetic escitalopram in the treatment of Chinese patients with MDD. Therefore, the double blind and innovator control(Lexapro®) design should be selected for this study. The drug titration method and dose are within the range specified in the instruction and patients with MDD are tolerant to the drug in practical clinical treatment.

The purpose of MDD patient treatment is to improve the core symptoms, prevent suicide, alleviate the side reactions caused by the antidepressant, and recover the life functions of patients. Generally, the treatment in the acute phase lasts for 6 to 8 weeks. In this study, the treatment in the acute phase lasts for 8 weeks.

The rating scales used in this study are standard psychiatric rating scales with good validity and are widely used in the study of antidepressants and in the treatment of patients with MDD. The high inter-investigator reliability and repeated measurement reliability of these scales(HAMD,MADRS,HAMA) have been proved by multiple studies. The clinical global impression (CGI) is a simple but convenient global impression scale. It is applicable to any patients treated and studied by the psychiatric department. The VAS-PI(Visual Analog Scale-Pain Intensity) is used to evaluate the reduction in pain intensity,a common symptom of patients with MDD. It has good reliability and validity. The Sheehan Disability Scale (SDS) was developed to assess functional impairment in three inter-related domains; work/school, social and family life.