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

This trial is testing whether a nasal spray version of (R)-ketamine — a rapid-acting drug — can quickly reduce suicidal thoughts and depression symptoms in people who are currently experiencing major depression with active suicidal intent. **You may be eligible if...** - You are an adult who has been diagnosed with major depressive disorder (MDD) without psychotic features - You currently have suicidal thoughts with intent to act on them (confirmed by a structured psychiatric interview) - Your depression severity score (MADRS) meets the required threshold at screening **You may NOT be eligible if...** - You do not have a confirmed MDD diagnosis - You do not have current active suicidal ideation with intent - You have psychotic features alongside your depression - Your depression severity score is below the required level - You have other conditions that would make ketamine unsafe for you Talk to your doctor to see if this trial is right for you.