title: Smoked cannabis for chronic neuropathic pain: a randomized controlled trial.
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.
  
  
  CONCLUSIONS
  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).
authors.affiliation: Department of Anesthesia, McGill University, Montréal, Que. mark.ware@muhc.mcgill.ca
authors.forename: Mark A
authors.initials: MA
authors.lastname: Ware
authors.forename: Tongtong
authors.initials: T
authors.lastname: Wang
authors.forename: Stan
authors.initials: S
authors.lastname: Shapiro
authors.forename: Ann
authors.initials: A
authors.lastname: Robinson
authors.forename: Thierry
authors.initials: T
authors.lastname: Ducruet
authors.forename: Thao
authors.initials: T
authors.lastname: Huynh
authors.forename: Ann
authors.initials: A
authors.lastname: Gamsa
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Bennett
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Collet
mesh_terms: D000328:Adult; D000368:Aged; D002908:Chronic Disease; D018592:Cross-Over Studies; D004311:Double-Blind Method; D013759:Dronabinol / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008385:Marijuana Smoking; D008875:Middle Aged; D009437:Neuralgia / Q000188:drug therapy*; D010147:Pain Measurement; D010919:Placebos; D011788:Quality of Life; D012890:Sleep / Q000187:drug effects; D016896:Treatment Outcome
chemical_list: D010919:Placebos; D013759:Dronabinol
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