An Exploratory Human Laboratory Experiment Evaluating Vaporized Cannabis in the Treatment of Neuropathic Pain From Spinal Cord Injury and Disease.
Using 8-hour human laboratory experiments, we evaluated the analgesic efficacy of vaporized cannabis in patients with neuropathic pain related to injury or disease of the spinal cord, most of whom were experiencing pain despite traditional treatment. After obtaining baseline data, 42 participants underwent a standardized procedure for inhaling 4 puffs of vaporized cannabis containing either placebo, 2.9%, or 6.7% delta 9-THC on 3 separate occasions. A second dosing occurred 3 hours later; participants chose to inhale 4 to 8 puffs. This flexible dosing was used to attempt to reduce the placebo effect. Using an 11-point numerical pain intensity rating scale as the primary outcome, a mixed effects linear regression model showed a significant analgesic response for vaporized cannabis. When subjective and psychoactive side effects (eg, good drug effect, feeling high, etc) were added as covariates to the model, the reduction in pain intensity remained significant above and beyond any effect of these measures (all P < .0004). Psychoactive and subjective effects were dose-dependent. Measurement of neuropsychological performance proved challenging because of various disabilities in the population studied. Because the 2 active doses did not significantly differ from each other in terms of analgesic potency, the lower dose appears to offer the best risk-benefit ratio in patients with neuropathic pain associated with injury or disease of the spinal cord.



A crossover, randomized, placebo-controlled human laboratory experiment involving administration of vaporized cannabis was performed in patients with neuropathic pain related to spinal cord injury and disease. This study supports consideration of future research that would include longer duration studies over weeks to months to evaluate the efficacy of medicinal cannabis in patients with central neuropathic pain.
VA Northern California Health Care System, Sacramento VA Medical Center, Mather, California; Department of Physical Medicine and Rehabilitation, University of California, Davis Medical Center, Lawrence J. Ellison Ambulatory Care Center, Sacramento, California. Electronic address: bwilsey@ucsd.edu.
Barth
B
Wilsey
Department of Psychiatry, University of California, San Diego, San Diego, California.
Thomas D
TD
Marcotte
Department of Psychiatry, University of California, San Diego, San Diego, California.
Reena
R
Deutsch
VA Northern California Health Care System, Sacramento VA Medical Center, Mather, California; Department of Physical Medicine and Rehabilitation, University of California, Davis Medical Center, Lawrence J. Ellison Ambulatory Care Center, Sacramento, California.
Holly
H
Zhao
VA Northern California Health Care System, Sacramento VA Medical Center, Mather, California; Department of Physical Medicine and Rehabilitation, University of California, Davis Medical Center, Lawrence J. Ellison Ambulatory Care Center, Sacramento, California.
Hannah
H
Prasad
VA Northern California Health Care System, Sacramento VA Medical Center, Mather, California; Department of Physical Medicine and Rehabilitation, University of California, Davis Medical Center, Lawrence J. Ellison Ambulatory Care Center, Sacramento, California.
Amy
A
Phan
D000280:Administration, Inhalation; D000328:Adult; D000700:Analgesics / Q000008:administration & dosage*; D001794:Blood Pressure / Q000187:drug effects; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D006930:Hyperalgesia / Q000188:drug therapy / Q000503:physiopathology; D008137:Longitudinal Studies; D008297:Male; D064086:Medical Marijuana / Q000008:administration & dosage*; D008875:Middle Aged; D009437:Neuralgia / Q000188:drug therapy* / Q000209:etiology*; D009483:Neuropsychological Tests; D017063:Outcome Assessment, Health Care; D010147:Pain Measurement; D056152:Respiratory Rate / Q000187:drug effects; D013119:Spinal Cord Injuries / Q000150:complications*; D014706:Verbal Learning / Q000187:drug effects; D014835:Volatilization
D000700:Analgesics; D064086:Medical Marijuana
Neuropathic pain; analgesia; cannabis; clinical trial; neuropsychological testing