Ketamine: An Update on Cellular and Subcellular Mechanisms with Implications for Clinical Practice.

BACKGROUND: Ketamine is one of the oldest hypnotic agents used to provide an anesthetic agent with analgesic properties and minimal suppressive effects on respiration. The ability of ketamine in modulating glutamatergic (N-methyl D-aspartate) pain receptors has made this anesthetic drug a new option for the management of patients with chronic pain syndromes. Further preclinical and clinical findings suggest ketamine may have wide ranging effects on both cognition and development. Recent advances have revealed an unprecedented role for ketamine in the acute management of depression.

OBJECTIVES: The purpose of this review is to integrate a number of basic science, preclinical, and clinical studies with the goal of providing insight into the possible signaling events underlying ketamine's biological effects in pain management, depression, cognition and memory, and neurodevelopment.

STUDY DESIGN: Narrative literature review.

SETTING: Health science library.

METHODS: A comprehensive literature search was performed for the following medical subject headings and keywords (ketamine, anesthesia, pain, analgesia, depression, NMDA receptors) on PubMed, Google Scholar, and Medline from 1966 to the present time. The search was then limited to those in the English language. The full text of the relevant articles were printed and reviewed by all authors.

RESULTS: We provided a comprehensive review of the literature that explored the pharmacologic aspects of ketamine from its conception as an anesthetic to its evolution as a drug used for treatment of depression and pain. To address the patient response variability observed in clinical studies, we have provided possible patient-specific factors that could contribute to outcome variability.

LIMITATIONS: Like any review, this study was limited by publication bias and missing information on negative studies which were denied publication.

CONCLUSIONS: Ketamine, an old anesthetic agent with analgesic properties, is currently being considered for treating patients with chronic pain and depression. The complex pharmacological characteristics of ketamine make this medication a multifaceted therapeutic option in these cases. Key Words: Ketamine, anesthetics, pain, depression, pharmacology.