Study Drug
During the induction phase, patients self-administered esketamine nasal spray twice a week for 4 weeks as a flexible-dose regimen, beginning at 28 mg (in those aged ≥65 years) or 56 mg. Subsequent doses could be adjusted (<65 years: 56 or 84 mg; ≥65 years: 28, 56, or 84 mg) based on efficacy and tolerability. All patients were also taking a newly initiated oral antidepressant (i.e., duloxetine, escitalopram, sertraline, or venlafaxine extended release).