A Study of Esketamine Nasal Spray in Korean Participants With Treatment-resistant Depression

This study tests esketamine nasal spray — a fast-acting treatment for severe depression — specifically in Korean patients whose depression has not improved with at least two different antidepressant medications. Esketamine works differently from traditional antidepressants and can start relieving symptoms within hours. **You may be eligible if...** - You are based in Korea and have been diagnosed with major depressive disorder - You have tried at least two antidepressants without adequate improvement (treatment-resistant depression) - You are 18 or older - You are currently taking an antidepressant and are willing to continue it alongside esketamine - You do not have active suicidal plans **You may NOT be eligible if...** - You have a history of psychosis, bipolar disorder type I, or certain other psychiatric conditions - You have a history of substance use disorder (especially alcohol, stimulants, or phencyclidine) - You have uncontrolled high blood pressure or serious heart or brain vessel disease - You are pregnant or breastfeeding Talk to your doctor to see if this trial is right for you.