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2006 · RCT

Zarate et al. 2006 - replication in TRD

A randomized trial of an NMDA antagonist in treatment-resistant major depression

Written by: Ira ZootMedical review status: Not yet clinically reviewed.Last updated: June 4, 2026Evidence: Zarate CA Jr et al.. Archives of General Psychiatry, 2006.

This page has been written and edited by the publisher. It has not been reviewed by a licensed clinician.

Quick answer
Why this study matters
The widely-cited replication that made TRD the primary indication for ketamine research and clinical use.
Population
18 patients with treatment-resistant depression
Intervention
Single IV ketamine infusion (0.5 mg/kg)
Comparator
Saline placebo, crossover design
Primary outcome
HAM-D score over 7 days

Key findings

  • 71% of patients met response criteria within 24 hours
  • 35% maintained response at 7 days
  • Established TRD as a target population

Limitations

  • Small sample
  • Single dose
  • Short follow-up

Read the original study →

Disclaimer
Educational summary only. A single study - even a landmark one - does not establish clinical practice. Discuss treatment decisions with a qualified clinician.
About the author

Publisher and editor of Ketalux, based in Chicago, Illinois. Ira is a ketamine therapy patient, not a clinician. This is editorial review, not medical review: Ira is not a licensed clinician and does not provide diagnosis or medical care. Ketalux does not accept compensation from providers in exchange for favorable editorial coverage, evidence ratings, recommendations, patient referrals, or organic provider ranking. Read the full publisher disclosure →

Educational use only. The content on this page is provided for general educational purposes and does not constitute medical advice, diagnosis, or treatment. Ketamine and related therapies carry risks and are appropriate only under qualified medical supervision. Always consult a licensed healthcare professional about your individual situation. Information may change as research evolves.