Cannabinoid analgesia as a potential new therapeutic option in the treatment of chronic pain.
OBJECTIVE
To review the literature concerning the physiology of the endocannabinoid system, current drug development of cannabinoid agonists, and current clinical research on the use of cannabinoid agonists for analgesia.


METHODS
Articles were identified through a search of MEDLINE (1966-August 2005) using the key words cannabis, cannabinoid, cannabi*, cannabidiol, nabilone, THC, pain, and analgesia. No search limits were included. Additional references were located through review of the bibliographies of the articles identified.


METHODS
Studies of cannabinoid agonists for treatment of pain were selected and were not limited by pain type or etiology. Studies or reviews using animal models of pain were also included. Articles that related to the physiology and pharmacology of the endocannabinoid system were evaluated.


RESULTS
The discovery of cannabinoid receptors and endogenous ligands for these receptors has led to increased drug development of cannabinoid agonists. New cannabimimetic agents have been associated with fewer systemic adverse effects than delta-9-tetrahydrocannabinol, including recent development of cannabis medicinal extracts for sublingual use (approved in Canada), and have had promising results for analgesia in initial human trials. Several synthetic cannabinoids have also been studied in humans, including 2 cannabinoid agonists available on the international market.


CONCLUSIONS
Cannabinoids provide a potential approach to pain management with a novel therapeutic target and mechanism. Chronic pain often requires a polypharmaceutical approach to management, and cannabinoids are a potential addition to the arsenal of treatment options.
Burns
Tammy L
TL
Creighton University Medical Center, Omaha, NE 68178-4879, USA.
Ineck
Joseph R
JR
D018712:Analgesics, Non-Narcotic / Q000494:pharmacology / Q000627:therapeutic use*; D000818:Animals; D063386:Cannabinoid Receptor Agonists; D063385:Cannabinoid Receptor Modulators / Q000378:metabolism*; D002186:Cannabinoids / Q000494:pharmacology / Q000627:therapeutic use*; D002908:Chronic Disease; D015195:Drug Design; D006801:Humans; D016239:MEDLINE; D010146:Pain / Q000188:drug therapy* / Q000378:metabolism
D018712:Analgesics, Non-Narcotic; D063386:Cannabinoid Receptor Agonists; D063385:Cannabinoid Receptor Modulators; D002186:Cannabinoids