Ketamine for chronic pain –is this a good idea?

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A recent phase 1 study explored the use of oral ketamine for chronic pain (J Pediatr 2013; 163: 194-200).

Ketamine has several mechanisms of actions in improving pain.  It is frequently used in emergency room settings because of its analgesic and dissociative amnestic qualities.  In addition, it has relatively little cardiorespiratory impact, a short half-life, and is better tolerated in children than adults.

Given the frequency of chronic pain in children and the relative paucity of treatment options, the authors aimed to determine whether ketamine in a short-term study (2 weeks) would be safe and effective.  This prospective study enrolled 12 patients who received ketamine 3 times per day at dosages of 0.25-1.5 mg/kg/dose .**

Pain diagnoses included chronic pancreatitis, Crohn’s disease, esophageal spasm, headache, joint pains, and other causes.  Median age was 16 years (range 11-19).

Results:

  • Two participants, both treated with 1.5 mg/kg/dose, experienced dose-limiting toxicities: sedation and anorexia.
  • Of the 12 patients, 5 had improvement in pain scores; 2 of these patients had complete resolution of pain which lasted >4 weeks off ketamine treatment.
  • There was evidence of norketamine accumulation in many patients.  Norketamine is the major metabolite of ketamine.

**Note: All medication dosages should be checked in standard references for individual patients.  This blog may have transcription errors with regard to dosages.

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