Study AK1113351, a Fixed Dose Study of 323U66 SR in the Treatment of Major Depressive Disorder (MDD) - a Multi-center, Placebo-controlled, Randomized, Double-blind, Parallel-comparison Study

This is a multi-center, placebo-controlled, randomized, double-blind, parallel-comparison study to confirm the efficacy of 323U66 Sustained Release (SR) orally administered to patients with MDD (Major Depressive Disorder) at doses level of 150 mg/day and 300 mg/day for 8 weeks based on the decrease in MADRS (Montgomery-Asberg Depression Rating Scale) total score, and to evaluate the safety based on adverse events, clinical laboratory tests and vital signs.