This will be a randomized, double-blind, placebo-controlled, multicenter study. Approximately 24 male and female adult participants diagnosed with TRD will participant in this study. There will be 4 study phases: a 4-week screening phase, a 1-day baseline phase, a double-blind treatment phase (Day 1 to Day 15), and a 1-week post-treatment (follow-up) phase. Firstly, 12 patients will be assigned to intranasal placebo or HS-10345 of 84mg. Extra 12 patients may be enrolled depending on the pharmacokinetics analysis of 84mg. Safety assessments will be performed throughout the study. The maximum study duration for a participant will be 7 weeks.
The purpose of this study is to assess the safety, tolerability and pharmacokinetics of intranasal HS-10345 (84mg) compared with placebo in participants with treatment-resistant depression (TRD).