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.
Ketamine given intravenously rapidly reduces depressive symptoms, with effects lasting at least a week. In an analysis of 17 randomized controlled trials with 809 participants, the benefit over placebo was larger for patients who had already failed two or more prior antidepressant trials. However, no patient-level clinical or demographic characteristics—such as age, sex, or diagnosis—could predict who would respond best, limiting the ability to personalize ketamine prescriptions. The findings confirm ketamine's broad effectiveness for depression but show that precision medicine approaches cannot yet guide treatment decisions.
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.
Higher body mass index (BMI) and obesity are linked to a stronger acute antidepressant effect from a single intravenous dose of ketamine in patients with treatment-resistant depression. In a randomized, double-blind, placebo-controlled trial, patients with obesity showed a significantly greater reduction in depression symptoms 24 hours after ketamine infusion compared to those with normal BMI. Overweight patients also showed a trend toward greater improvement. Similar but weaker effects were observed at 72 hours. The findings suggest that obesity may enhance the rapid antidepressant response to ketamine, which could have clinical relevance for the many patients with both major depressive disorder and obesity.