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2019 · RCT

Phillips et al. 2019 - repeat dosing

Single and repeated ketamine infusions for reduction of treatment-resistant depression

Written by: Ira ZootMedical review status: Not yet clinically reviewed.Last updated: June 4, 2026Evidence: Phillips JL et al.. American Journal of Psychiatry, 2019.

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
Helped shape the now-common clinical practice of multi-session induction followed by maintenance dosing.
Population
41 patients with TRD
Intervention
Single vs repeated (6) IV ketamine infusions
Comparator
Within-subject comparison
Primary outcome
MADRS response and remission

Key findings

  • Repeated dosing produced higher response rates than single dose
  • Median time to relapse was modest without maintenance
  • Supports a course-based protocol approach

Limitations

  • Modest sample
  • Open-label maintenance phase

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.