Research Abstracts

The Journal of Informed Pharmacotherapy 2001;4:402.

Dextromethorphan: A review of its use in the management of chronic pain

Janice K. Yeung, BSc.(Pharm), May Ong, MD, Roger Shick, MD FRCPC, Angela Kim-Sing, Pharm D, FCSHP 

St. Paul's Hospital Pain Center, Department of Psychiatry and the Department of Pharmacy, St. Paul's Hospital, Vancouver, British Columbia, Canada.

Canadian Society of Hospital Pharmacists (British Columbia Branch) Residency Research Presentation Night, Vancouver, British Columbia, Canada. May 10, 2000. (Unfunded study).


Context

Allodynia and hyperalgesia of the central nervous system are thought to result from the activation of N-methyl-D-aspartate (NMDA) receptors. The oral antitussive, dextromethorphan, is a readily available NMDA receptor antagonist known to inhibit wind-up and central hyperexcitability of dorsal horn neurons.

Objectives

The objective of this study was to determine the efficacy, safety and toxicity of dextromethorphan in the management of chronic pain.

Setting

A Canadian adult teaching hospital.

Design

A retrospective chart review and follow-up study conducted from June 1999 to June 2000.

Main Outcome Measures

Primary endpoints included pain control assessed on a 0 to 5 point pain scale and adverse events associated with dextromethorphan.

Results

Twenty-four patients prescribed dextromethorphan as an outpatient for the management of chronic pain were identified and evaluated. Fibromyalgia was the primary indication for dextromethorphan in these patients. The average daily maintenance dose of dextromethorphan prescribed was 150-200mg/day. Six patients were followed over a 12 month period. Data on compliance, efficacy and adverse effects experienced with dextromethorphan were tabulated. Using a 0 to 5 point pain scale, pain was assessed at three month intervals by the patient for a two week period and by a telephone interview conducted by the investigator. Three patients discontinued dextromethorphan after three, four and five months respectively with no improvement in pain control. For those whose pain responded to dextromethorphan, pain scoring decreased an average of one level on a 0 to 5 point pain scale. Patients commonly reported that dextromethorphan did not eliminate pain, but made it more tolerable. Patients noted increased mobility, improved sleep and overall management of pain. Side effects were frequent, but acceptable to the patient. 

Conclusions

Dextromethorphan should be reserved as an adjunct for chronic pain associated with fibromyalgia where all other therapies have failed.


Copyright © 2000 by the Journal of Informed Pharmacotherapy. All rights reserved.