A single 40-minute intravenous infusion of esketamine at either 0.20 mg/kg or 0.40 mg/kg produced a rapid and robust antidepressant effect in patients with treatment-resistant depression, with significant improvement in depression scores within two hours. The higher and lower doses were similarly effective, but the lower dose may offer better tolerability. Common side effects included headache, nausea, and transient dissociation that resolved within four hours.
Intranasal esketamine temporarily impairs cognitive performance and increases mental effort and sleepiness in healthy participants. At 40 minutes after dosing, performance on five cognitive tests (Detection, Identification, One-Card Learning, One Back, and Groton Maze Learning) was significantly worse compared with placebo. These effects resolved by 2 hours postdose, with no differences between esketamine and placebo at 2, 4, or 6 hours. Participants reported greater mental effort at 40 minutes and increased sleepiness at 40 minutes and 2 hours, which also returned to placebo levels later. Common mild adverse events included dizziness, nausea, attention disturbance, and fatigue.