When a patient has failed two or more antidepressants, the clinical picture shifts. The question is no longer whether their medication needs adjusting — it is whether the standard pharmacological approach is the right tool at all. This is the population ketamine and Spravato were built for. And over the past decade, the evidence has moved from promising to conclusive.
What the Numbers Actually Show
In the landmark ELEKT-D trial published in the New England Journal of Medicine (Anand et al., 2023), 55.4% of patients receiving IV ketamine achieved a meaningful treatment response — defined as at least a 50% reduction in depressive symptoms — compared to 41.2% in the ECT group. Remission rates reached 32.3% to 37.9% depending on the measure used. Critically, ketamine achieved this with significantly fewer cognitive side effects than ECT.
A 2023 systematic review and meta-analysis published in eClinicalMedicine, drawing on 49 randomized controlled trials and over 3,200 patients, found that IV racemic ketamine produced remission rates 2.5 to nearly 4 times higher than placebo. Higher-dose regimens showed sustained remission through repeated treatment courses.
For Spravato, the 2025 JAMA Psychiatry trial by Janik et al. demonstrated that esketamine monotherapy significantly outperformed placebo in reducing depressive symptom severity — one of the first trials to examine esketamine as a standalone treatment rather than an adjunct to an oral antidepressant.
Speed Is the Differentiator
Traditional antidepressants require four to six weeks before a meaningful effect is observed — if one occurs at all. Ketamine can produce measurable symptom reduction within 24 to 72 hours of the first infusion. For patients with active suicidal ideation or severe functional impairment, this speed is not a convenience. It is clinically significant and changes the risk calculus entirely.
PTSD: A Compelling and Growing Evidence Base
Beyond depression, ketamine is showing real promise for chronic PTSD. In the first randomized controlled trial of repeated ketamine infusions for chronic PTSD (Feder et al., 2021, American Journal of Psychiatry), 67% of patients in the ketamine group were classified as treatment responders, compared to 20% in the placebo group. Symptom reduction was rapid, clinically meaningful, and statistically significant. This matters especially for veterans, first responders, and survivors of trauma who have exhausted standard treatment options.
Why Two Out of Three?
Across the strongest available trials, roughly two out of every three patients who receive properly administered IV ketamine or Spravato achieve either significant symptom reduction or full remission. That is not a guarantee — individual outcomes vary, maintenance is required, and these treatments are not appropriate for everyone. But for a population that has, by definition, not responded to standard care, a 55–67% meaningful response rate represents a clinical frontier that did not exist in psychiatry a generation ago.
At Parker Neuroscience, these numbers inform everything — the protocols, the monitoring standards, the follow-up care, and the integration support we provide. Evidence-based does not mean one size fits all. It means knowing what the data shows and building a clinical approach around it.
What This Means for You
If you or someone you care about has been through the standard treatment pathway without adequate results, the evidence no longer supports waiting. These are not experimental treatments. They are among the most studied rapid-acting interventions in modern psychiatry, supported by randomized controlled trials published in the New England Journal of Medicine, JAMA Psychiatry, and the American Journal of Psychiatry. The question is not whether these treatments work. The question is whether they are right for you — and that begins with a conversation.
References
1. Anand A, Mathew SJ, Sanacora G, et al. Ketamine versus ECT for nonpsychotic treatment-resistant major depression. N Engl J Med. 2023;388(25):2315–2325. doi:10.1056/NEJMoa2302399
2. Bahji A, Vazquez GH, Zarate CA Jr. Comparative efficacy of racemic ketamine and esketamine for depression: a systematic review and meta-analysis. eClinicalMedicine. 2023;63:102103. doi:10.1016/j.eclinm.2023.102103
3. Janik A, Qiu X, Lane R, et al. Esketamine monotherapy in adults with treatment-resistant depression: a randomized clinical trial. JAMA Psychiatry. 2025;82(9):877–887. doi:10.1001/jamapsychiatry.2025.1317
4. Feder A, Costi S, Rutter SB, et al. A randomized controlled trial of repeated ketamine administration for chronic PTSD. Am J Psychiatry. 2021;178(2):193–202. doi:10.1176/appi.ajp.2020.20050596
5. Guo H, Tang L, He M, et al. Comparative safety and tolerability of ketamine and esketamine for major depressive disorder: a systematic review and meta-analysis. Front Pharmacol. 2025;16:1681060. doi:10.3389/fphar.2025.1681060