Adjunctive intranasal esketamine is more effective than placebo for treating major depressive disorder. Pooling five randomized, double-blind trials with 774 patients, esketamine outperformed placebo on depression rating scale score change, response, and remission. The effect was statistically significant across different study samples and baseline antidepressant regimens. Esketamine appears to be an effective treatment strategy for patients who are treatment-resistant or acutely suicidal.
In a double-blind trial, 99 people with treatment-resistant depression received either a single intravenous dose of ketamine (0.1, 0.2, 0.5, or 1.0 mg/kg) or midazolam (0.045 mg/kg). Among them, 45 had high baseline anxiety and 54 did not. No significant difference in depression improvement was found between the ketamine and midazolam groups for either anxious or nonanxious participants at 1 or 3 days after infusion. The results suggest that ketamine may work similarly for both anxious and nonanxious treatment-resistant depression, unlike some traditional antidepressants.
A single 1-hour inhalation of 25% nitrous oxide improves depressive symptoms in patients with severe treatment-resistant major depression as effectively as 50% nitrous oxide, but with substantially fewer adverse effects. In a phase 2 crossover trial with 24 patients, both concentrations significantly reduced depression scores on the Hamilton Depression Rating Scale compared to placebo over two weeks. The 25% dose showed significant improvements at week 1 and week 2, while the 50% dose showed significant improvement at week 2. Adverse events declined substantially with the lower dose.