Cannabinoids and pain management

Abstract

controlled, parallel-group trial studying the analgesic effects of two different doses of nabilone, a synthetic analogue of THC, in managing acute postoperative pain following major surgery. 5 Unfortunately, the study was prematurely terminated after 18 months. The results of this study demonstrated that nabilone administration was not associated with a decrease in morphine consumption in patients following major surgery. In addition, nabilone at high doses significantly increased pain scores at rest and upon movement. The investigator concluded that, although cannabinoids may be effective in relieving chronic pain in humans, their role in the treatment of acute postoperative pain is uncertain, and requires further clinical evaluation. Small sample size, early termination of the study, and the lack of standardization of surgical procedures with possible variation in intensity of postoperative pain (e.g., total hip replacement vs total knee replacement) may limit the conclusions that can be drawn from this study. Previous studies examining cannabinoids in treating postoperative pain have also demonstrated only a modest analgesic effect. 6 A systematic review concluded that cannabinoids are no more effective than codeine in controlling acute pain, although this was a conclusion based upon only one Phase II study. 7 While the current study suggests a very limited role for cannabinoids in postoperative pain, it is important to recognize that this may change as novel, more potent and more specific synthetic cannabinoid analogs, with limited central nervous system effects, are developed. The role of cannabinoids in managing chronic pain is more promising. A systematic review of studies available prior to 2002 identified seven randomized controlled trials examining cannabinoids in chronic pain. These studies demonstrated that oral THC preparations exhibit a moderate analgesic effect, equivalent