Efficacy, Safety and Pharmacokinetic Study of Inhaled Esketamine in Treatment-resistant Depression

This is a randomized, multiple dose, placebo-controlled, double-blind, multicentre study of Esketamine DPI, inhalation powder delivered via dry powder inhaler (DPI) in participants with TRD in the course of MDD. There are 3 study phases: Screening phase, a two weeks double-blind treatment phase and a 6-week follow-up phase. Participants are to be randomized in 1:1:1:1 ratio to receive placebo or one of the three doses of Esketamine DPI. Participants from each group will receive different dosing sequences, consider as a single dose, corresponding to low, medium, high Esketamine dose or placebo. Participants will undergo one cycle of treatment consisting of four doses of Esketamine DPI or placebo over 14-day period. Participants safety will be monitored throughout the study.