Pubdate: Tue, 5 Oct 2010
Source: Canadian Medical Association Journal (Canada)
Copyright: 2010 Canadian Medical Association
Contact:  http://www.cmaj.ca/
Details: http://www.mapinc.org/media/754
Authors: Mark A. Ware, MBBS, Tongtong Wang, PhD, Stan Shapiro, PhD, 
Ann Robinson, RN, Thierry Ducruet, MSc, Thao Huynh, MD, Ann Gamsa, 
PhD, Gary J. Bennett, PhD and Jean-Paul Collet, MD PhD
Full: text http://www.cmaj.ca/cgi/reprint/182/14/E694
Bookmark: http://www.mapinc.org/mmj.htm (Cannabis - Medicinal)

Research

SMOKED CANNABIS FOR CHRONIC NEUROPATHIC PAIN: A RANDOMIZED CONTROLLED TRIAL

Background: Chronic neuropathic pain affects 1%-2% of the adult 
population and is often refractory to standard pharmacologic 
treatment. Patients with chronic pain have reported using smoked 
cannabis to relieve pain, improve sleep and improve mood.

Methods: Adults with post-traumatic or postsurgical neuropathic pain 
were randomly assigned to receive cannabis at four potencies (0%, 
2.5%, 6% and 9.4% tetrahydrocannabinol) over four 14-day periods in a 
crossover trial. Participants inhaled a single 25-mg dose through a 
pipe three times daily for the first five days in each cycle, 
followed by a nine-day washout period. Daily average pain intensity 
was measured using an 11-point numeric rating scale. We recorded 
effects on mood, sleep and quality of life, as well as adverse events.

Results: We recruited 23 participants (mean age 45.4 [standard 
deviation 12.3] years, 12 women [52%]), of whom 21 completed the 
trial. The average daily pain intensity, measured on the 11-point 
numeric rating scale, was lower on the prespecified primary contrast 
of 9.4% v. 0% tetrahydrocannabinol (5.4 v. 6.1, respectively; 
difference = 0.7, 95% confidence interval [CI] 0.02-1.4). 
Preparations with intermediate potency yielded intermediate but 
nonsignificant degrees of relief. Participants receiving 9.4% 
tetrahydrocannabinol reported improved ability to fall asleep 
(easier, p = 0.001; faster, p ( 0.001; more drowsy, p = 0.003) and 
improved quality of sleep (less wakefulness, p = 0.01) relative to 0% 
tetrahydrocannabinol. We found no differences in mood or quality of 
life. The most common drug-related adverse events during the period 
when participants received 9.4% tetrahydrocannabinol were headache, 
dry eyes, burning sensation in areas of neuropathic pain, dizziness, 
numbness and cough.

Conclusion: A single inhalation of 25 mg of 9.4% tetrahydrocannabinol 
herbal cannabis three times daily for five days reduced the intensity 
of pain, improved sleep and was well tolerated. Further long-term 
safety and efficacy studies are indicated. (International Standard 
Randomised Controlled Trial Register no. ISRCTN68314063)

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MAP posted-by: Richard Lake