A Study to Evaluate the Efficacy, Safety, and Pharmacokinetic Characteristics of (R)-Ketamine Hydrochloride Nasal Spray in Patients With Depression and Acute Suicidal Ideation or Behavior

Change From Baseline in Montgomery Asberg Depression Rating Scale Total Score During Double-blind Phase

The MADRS is a clinician-rated scale designed to measure depression severity and detects changes due to antidepressant treatment. The test consists of 10 items, each of which is scored from 0 (item not present or normal) to 6 (severe or continuous presence of the symptoms), for a total score of 60. Higher scores represent a more severe condition.

Time frame: Days 1 (4 hours postdose), 4, 8, 11, 15, 18, 22 and Day 25

Number of Participants who Achieved Response （≥50% decrease from baseline MADRS total score）Through the Double-blind Phase

Time frame: Days 1 (4 hours postdose),2, 4, 8, 11, 15, 18, 22 and Day 25

Number of Participants Who Achieved Remission (MADRS Total Score Less Than or Equal to [<=] 12) Through the Double-blind Phase

Time frame: Days 1 (4 hours postdose), 2, 4, 8, 11, 15, 18, 22 and Day 25

5. Change From Baseline in Clinical Global Impression- Severity of Suicidality-Revised (CGI-SS-R) During Double-blind Phase

CGI-SS-R was derived from the Clinical Global Impression Severity Scale (CGI-S), a global rating scale that gives an overall measure of the severity of a participants illness. The CGI-SS-R rating is scored on a 7-point scale from 0 (normal, not at all suicidal) to 6 (among the most extremely suicidal participants). A higher score indicates a more severe condition and a reduction in score indicates improvement (that is, lower severity of suicidality).

Time frame: Days 1 (4 hours postdose), 2, 4, 8, 11, 15, 18, 22 and Day 25

Number of Participants Who Achieved Resolution of Suicidality (CGI-SS-R Score of 0 or 1) Through Double-blind Phase

Time frame: up to Day 25

Change From Baseline in Clinical Global Impression of Imminent Suicide Risk (CGI-SR-I) Scale Total Score During Double-blind Phase

The CGI-SR-I is a scale summarizing the clinician's best assessment of the likelihood that the participant will attempt suicide in the next 7 days. The CGI-SR-I rating is scored on a 7-point scale: where' 0 (no imminent suicide risk); 1 (minimal imminent suicide risk), 2 (mild imminent suicide risk), 3 (moderate imminent suicide risk), 4 (marked imminent suicide risk), 5 (severely imminent suicide risk), 6 (extreme imminent suicide risk). Higher score indicates a more severe condition. Negative change in score indicates improvement.

Time frame: Days 1 (4 hours postdose), 2, 4, 8, 11, 15, 18, 22 and Day 25

8. Change From Baseline in Beck Hopelessness Scale (BHS) Total Score During Double-blind Phase

BHS is a self-reported measure to assess one's level of negative expectations or pessimism regarding future. It consists of 20 true-false items that examine respondent's attitude over past week by either endorsing a pessimistic statement or denying an optimistic statement; 9 are keyed false and 11 are keyed true. For every statement, each response was assigned score of 0 or 1. Total BHS score is sum of item responses, ranged from 0-20, where higher score represented higher level of hopelessness.

Time frame: Baseline, Days 8 ,15 and 25

Change From Baseline in Beck Scale for Suicide Ideation -Chinese Version (BSI-CV) Total Score During Double-blind Phase

BSI-CV is a self-reported measure with 19 items, scored on a 3-point scale (0 to 2). The final score ranges from 0 to 38, with higher scores indicating a greater likelihood of suicide.

Time frame: Baseline, Days 8 ,15 and 25

Number of Participants With Treatment Emergent Adverse Events (TEAEs)、Vital Signs Abnormalities、Abnormal Electrocardiogram (ECG) Values et al: DB Treatment Phase

Time frame: up to Day 25

Area Under the Plasma Concentration-Time Curve From Time Zero to Infinite Time (AUC [0-infinity])

Time frame: up to Day 25

Maximum Plasma Concentration [Cmax]

Time frame: up to Day 25

plasma elimination half-life [T1/2]

Time frame: up to Day 25