The Analgesic Effect of Vaporized Cannabis on Neuropathic Pain in Spinal Cord Injury

INVESTIGATOR: Barth Wilsey, M.D.

STUDY LOCATION: University of California, Davis

PROJECT TITLE: The Analgesic Effect of Vaporized Cannabis on Neuropathic Pain in Spinal Cord Injury

PROJECT TYPE: Clinical Study

STATUS: COMPLETE

RESULTS:

We conducted a double-blind, placebo-controlled, crossover study evaluating the analgesic efficacy of vaporized cannabis in subjects, the majority of whom were experiencing neuropathic pain despite traditional treatment. Thirty-nine patients with central and peripheral neuropathic pain underwent a standardized procedure for inhaling medium-dose (3.53%), low-dose (1.29%), or placebo cannabis with the primary outcome being visual analog scale pain intensity. Psychoactive side effects and neuropsychological performance were also evaluated. Mixed-effects regression models demonstrated an analgesic response to vaporized cannabis. There was no significant difference between the 2 active dose groups’ results (P > .7). The number needed to treat (NNT) to achieve 30% pain reduction was 3.2 for placebo versus low-dose, 2.9 for placebo versus medium-dose, and 25 for medium- versus low-dose. As these NNTs are comparable to those of traditional neuropathic pain medications, cannabis has analgesic efficacy with the low dose being as effective a pain reliever as the medium dose. Psychoactive effects were minimal and well tolerated, and neuropsychological effects were of limited duration and readily reversible within 1 to 2 hours. Vaporized cannabis, even at low doses, may present an effective option for patients with treatment-resistant neuropathic pain.

The full results of this study have been published in the Journal of Pain.

ABSTRACT:

The present study will be designed to evaluate the analgesic effects of vaporized cannabis in patients with neuropathic pain due to spinal cord injury. A within-subject crossover study of the effects of cannabis (3.5% and 1.7%) versus placebo on spontaneous and evoked pain will be performed. Both pain intensity and pain unpleasantness will be assessed to see if marijuana affects sensory-discriminative pain more or less than the motivational-affective component. If present, areas of mechanical allodynia will be assessed with repeated testing to determine the degree of the allodynia regression (if any) after inhaling cannabis via a vaporizer. Heat evoked pain will be studied using mild to moderately painful heat stimuli delivered to the painful area of the subject's body using an electronically controlled Peltier contact thermode via the Medoc TSA 2001 quantitative sensory tester. Neuropsychological functioning (attention, learning and memory, and psychomotor performance) will be evaluated with the Digit Symbol Modalities Test, the Hopkins Verbal Learning Test and the Grooved Pegboard Test before and after the administration of vaporized cannabis. The degree of antinociception will then be compared with neuropsychological effects of cannabis for a synopsis of the relative effectiveness (efficacy versus side-effects) of the doses employed.

The hypothesis will be that vaporized cannabis can induce dose dependent antinociceptive changes in spontaneous and evoked pain in subjects with neuropathic pain. The second hypothesis will be that the higher dose employed induce a greater degree of antinociception that is not independent of differences in mood, cognition and psychomotor performance. Finally, it is hypothesized that an interaction with time will occur such that antinociception will outlast changes in cognitive impairment and psychomotor performance.

PUBLICATIONS:

Type:

Title:

Journal Article Wilsey B, Marcotte T, Deutsch R, Gouaux B, Sakai S, Donaghe H. (2013). Low-Dose Vaporized Cannabis Significantly Improves Neuropathic Pain. J Pain. 2013 Feb;14(2):136-48. doi: 10.1016/j.jpain.2012.10.009. Epub 2012 Dec 11.

San Diego schools look to take mystery and misinformation out of medical marijuana

Jared Aarons, ABC 10News San Diego, September 10, 2019

Starting this fall, the Pacific College of Oriental Medicine is offering the first-ever certificate program specializing in medical marijuana.

The three-semester class promises to teach health care professionals the basics of medical cannabis, so they can begin to use it in their practice.

"We thought it was important for health care professionals to have objective information about medical marijuana," says school President Jack Miller.

Miller says part of the program's purpose is to help dispel some of the myths surrounding medical marijuana.

Read the rest of the story here


CMCR announces $3M in new research grants to California investigators

The Center for Medicinal Cannabis Research (CMCR) at UC San Diego has been a leader in medical marijuana research since 2000. In the past CMCR has allocated funds to investigators in California to conduct some of the first proof of principle clinical trials of cannabis in neuropathic pain and multiple sclerosis.

With the recent allocation of new funding to CMCR as part of Proposition 64, the CMCR has launched a new wave of grant applications aimed at examining both the efficacy and safety of medicinal cannabinoids. CMCR issued a call for applications to investigators in California in April 2019, received 66 letters of intent from 19 California institutions, and invited 26 applications for primary and pilot studies. Based on external peer review, advice of the CMCR’s National Advisory Council, and rating of attentiveness to CMCR priorities, the Center has selected 5 studies for funding this year. The studies to be funded are listed in the table below.

Study title Principal Investigator
Full funding amount
Effects of Cannabidiol (CBD) versus Placebo as an Adjunct to Treatment in Early Psychosis: Understanding the Mechanism and Mediators of Action Kristin Cadenhead, MD (UC San Diego)  $825,000 
Therapeutic Response of Cannabidiol in Rheumatoid Arthritis Veena Ranganath, MD (UCLA)  $825,000
Cannabidiol for Sedative/Hypnotic-sparing Management of Insomnia in Adults Mariana Cherner, PhD (UC San Diego)  $825,000
Cannabidiol as a Strategy to Treat Alcohol Dependence Giordano de Guglielmo, PhD (UC San Diego)  $300,000
The Role of Cannabidiol (CBD) in Regulating Meal Time Anxiety in Anorexia Nervosa: Safety, Tolerability and Pharmacokinetics Emily Gray, MD (UC San Diego)  $300,000

CMCR anticipates issuing a new call for applications in 2020.

Congratulations to the new CMCR Investigators!

- Igor Grant, MD, Director


The CBD Expert Series: Q&A with a National Leader in Cannabis Research

Nick Musica, CBD Oil Review, August 21, 2019

Recently, Nick Musica of CBD Oil Review had the privilege of speaking with one of the most influential figures in cannabis research, Dr. Igor Grant. Dr. Grant is the Director of the Center for Medicinal Cannabis Research (CMCR) at the University of California, San Diego, as well as a Distinguished Professor in the Department of Psychiatry.

Current CMCR studies are examining the effects of cannabis, and cannabidiol (CBD) specifically, on conditions like autism, psychosis, bipolar disorder, and pain, to name a few.

There is, quite possibly, no one who understands the benefits and effects of CBD better than Dr. Grant. Meet the researcher behind the research.

Read the article here


More News

Click here to access the CMCR news archives.

Igor Grant, MD

Marijuana as Medicine: Can We See Past the Smoke?
North American Cannabis Summit presentation January 2019 (PDF)


Igor Grant, MD

Introduction/Overview
CMCR Symposium, June 2018


Daniele Piomelli, MD, PhD, PharmD

The health impact of cannabis
CMCR Symposium, June 2018


Ziva Cooper, PhD

Therapeutic potential of cannabis for pain alone and as an adjunct to opioids
CMCR Symposium, June 2018


Iain McGregor, PhD

Medicinal cannabis research down under: Introducing the Lambert Initiative for Cannabinoid Therapeutics
CMCR Symposium, June 2018


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