Study register · detailRCT (cross-over) · Chronic Pain · 2010
Smoked cannabis for chronic neuropathic pain: a randomized controlled trial
Ware et al.·Canadian Medical Association JournalImpact 1.4
Clear benefitGRADEModerate442 citations
Samplen = 23 Pat.
Durationfour 14-day periods
ControlPlacebo cannabis
EndpointNRS
Blindingdoppelblind
DesignRCT (cross-over)
Cannabinoidthc
Max. dose75.0 mg
Routeinhalativ
”Key finding
Cannabis with 9,4% THC significantly reduced pain intensity by 0,7 points (5,4 vs. 6,1) and improved sleep quality and sleep onset time, but was associated with headache and other adverse effects.
Summary
Crossover RCT, n=23 (21 completers) with post-traumatic or postoperative neuropathic pain. Inhaled cannabis (0%, 2.5%, 6%, 9.4% THC) over four 14-day cycles (3×25 mg/day for 5 days, 9-day washout). Primary contrast 9.4% vs. 0% THC: mean pain intensity (11-point scale) 5.4 vs. 6.1 (difference=0.7, 95% CI 0.02–1.4, p<0.05). Improved sleep (easier falling asleep p=0.001, faster p<0.001, fewer wake periods p=0.01). Most common adverse effects with 9.4% THC: headache, dry eyes, burning, dizziness.
P
PopulationAdults with post-traumatic or postoperative neuropathy, n=23 (21 completers), mean age 45,4 years
I
InterventionSmoked cannabis 0%, 2,5%, 6% and 9,4% THC, 25 mg single dose 3×/day for 5 days per period
C
ControlPlacebo cannabis (0% THC)
O
OutcomeMean daily pain intensity significantly reduced for 9,4% vs. 0% THC (5,4 vs. 6,1; difference 0,7; 95% CI 0,02–1,4)
Confidence in the evidence
Very lowLowModerateHigh
Moderate
The third of four GRADE levels, the effect estimate is probably reliable.
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).