Study to Evaluate the Efficacy, Safety and Tolerability of Bupropion Hydrochloride Extended-release Tablet, and Escitalopram Oxalate Capsule in Subjects With Major Depressive Disorder

This multi-centre study will follow a randomised, double-blind, parallel-group, active-controlled design and will evaluate the efficacy, safety and tolerability of bupropion extended-release (XL) (300 mg/day) compared with escitalopram (10-20 mg/day) in outpatients and inpatients with major depressive disorder (MDD). The total duration of the study will be 11 weeks consisting of three phases. The screening phase (phase I) will be lasting for 0-14 days, subjects will be randomised to bupropion XL or escitalopram in a 1:1 ratio for acute phase treatment phase (phase II) for 8 weeks. There are 3 dose levels during this acute treatment phase. The 3-dose level plan is designed to ensure each drug is titrated according to the prescribing information and to reach an optimal clinical dose. Finally patients will enter the taper phase (phase III) for up to 1 week to assess and reduce the possible withdrawal symptoms. In China almost all existing antidepressants are available on the market, but bupropion XL has not yet been approved. This Phase III clinical trial will be used for the purpose of registering bupropion XL in China.