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Randomized Controlled Trial
. 2010 Oct 5;182(14):E694-701.
doi: 10.1503/cmaj.091414. Epub 2010 Aug 30.

Smoked cannabis for chronic neuropathic pain: a randomized controlled trial

Mark A Ware  1 , Tongtong Wang, Stan Shapiro, Ann Robinson, Thierry Ducruet, Thao Huynh, Ann Gamsa, Gary J Bennett, Jean-Paul Collet
Affiliations
Randomized Controlled Trial

Smoked cannabis for chronic neuropathic pain: a randomized controlled trial

Mark A Ware et al. CMAJ. .

Abstract

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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Figures

Figure 1
Figure 1
Flow of patients through the randomized controlled trial.
Figure 2
Figure 2
Levels of tetrahydrocannabinol (THC) in plasma after inhalation of a single dose. Data are presented as means and standard deviations.
See this image and copyright information in PMC

Comment in

  • Volunteering overseas made easy.
    Flegel K, MacDonald N, Hébert PC. Flegel K, et al. CMAJ. 2010 Oct 5;182(14):1493. doi: 10.1503/cmaj.100734. Epub 2010 Jun 7. CMAJ. 2010. PMID: 20530159 Free PMC article. No abstract available.

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