Background

The purpose of this study was to assess the efficacy and safety and to explore the dose response of esketamine intravenous (IV) infusion in patients with treatment-resistant depression (TRD).

Methods

This multicenter, randomized, placebo-controlled trial was conducted in 30 patients with TRD. Patients were randomly assigned 1:1:1 to receive an IV infusion of .20 mg/kg or .40 mg/kg esketamine or placebo over 40 minutes on day 1. The primary end point was change in Montgomery–Åsberg Depression Rating Scale total score from day 1 (baseline) to day 2. Nonresponders who received placebo on day 1 were randomly assigned again 1:1 to IV esketamine .20 mg/kg or .40 mg/kg on day 4. Secondary efficacy and safety measures were also evaluated.

Results

Of the enrolled patients, 97% (29 of 30) completed the study. The least squares mean changes (SE) from baseline to day 2 in Montgomery–Åsberg Depression Rating Scale total score for the esketamine .20 mg/kg and .40 mg/kg dose groups were −16.8 (3.00) and −16.9 (2.61), respectively, and showed significant improvement (one-sided p = .001 for both groups) compared with placebo (−3.8 [2.97]). Esketamine showed a rapid (within 2 hours) and robust antidepressant effect. Treatment-emergent adverse events were dose dependent. The most common treatment-emergent adverse events were headache, nausea, and dissociation; the last-mentioned was transient and did not persist beyond 4 hours from the start of the esketamine infusion.

Conclusions

A rapid onset of robust antidepressant effects was observed in patients with TRD after a 40-minute IV infusion of either .20 mg/kg or .40 mg/kg of esketamine. The lower dose may allow for better tolerability while maintaining efficacy.