FWD: Medscape-Low Dose Ketamine

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From: byrd45 (Original Message) Sent: 6/7/2005 9:36 AM
NOTE: To view the article with Web enhancements, go to:
http://www.medscape.com/viewarticle/490806

Laurie Barclay

Oct. 6, 2004 - Low-dose ketamine may be effective for the treatent of
chronic regional pain syndrome (CRPS), according to a retrospective
review published in the October issue of Pain Medicine.

"CRPS is a disorder that can be accompanied by severe pain that is
often both chronic and resistant to conventional therapy," write
Graeme E. Correll, BE, MBBS, FANZCA, from Mackay Base Hospital in
Queensland, Australia, and colleagues. "It is possible that a more
successful approach to desensitization therapy using an NMDA
antagonist such as ketamine requires a more individualized stepwise
tailoring of the dosage (i.e., infusion rate) and duration of drug
administration."

The authors reviewed the medical records of 33 inpatients with CRPS
treated in Queensland at least once with a continuous subanesthetic
intravenous infusion of ketamine. After the first treatment, 25
patients (76%) had complete pain relief, six patients (18%) had
partial relief, and two patients (6%) had no relief. Of the 33
patients, 54% remained pain-free for at least three months and 31%
remained pain-free for at least six months after the first course of
therapy.

Because of relapse, 12 of these patients received a second course of
ketamine, and two patients received a third course. All 12 of these
patients had complete relief of their CRPS pain. After the second
treatment, 58% of 12 patients experienced relief for at least one
year, and nearly one third remained pain-free for at least three years.

The most frequently observed adverse effect was a feeling of
inebriation. Six patients had hallucinations, and four patients had
changes in liver enzymes that resolved when the infusion was
terminated. Less frequent adverse effects were lightheadedness,
dizziness, and nausea.

"This retrospective review suggests that limited subanesthetic
inpatient infusions of ketamine may offer a promising therapeutic
option in the treatment of appropriately selected patients with
intractable CRPS," the authors write. "More study is needed to further
establish the safety and efficacy of this novel approach."

While awaiting further data, the authors recommend limiting the
duration of a continuous ketamine infusion treatment to a maximum of
four to five days, limiting the maximum infusion rate to about 25 to
50 mg per hour, and combining ketamine with a suitable neuroprotective
agent.