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.

New Study Analyzes Cost Effectiveness of Smoked Cannabis to Treat Chronic Neuropathic Pain

Kathryn Ryan, Mary Ann Liebert, Inc., January 29, 2019

Smoked cannabis as an adjunctive second-line therapy to treat chronic peripheral neuropathy can be both effective and cost-effective. The results of a new study simulating its use in one million patients are published in Cannabis and Cannabinoid Research, a peer-reviewed journal from Mary Ann Liebert, Inc., publishers. Click here to read the full-text article free on the Cannabis and Cannabinoid Research website.

In the article entitled “A Cost-Effectiveness Model for Adjunctive Smoked Cannabis in the Treatment of Chronic Neuropathic Pain,” David Grelotti, MD, University of California San Diego (La Jolla) and coauthors from UCSD, University of California Center for Medicinal Cannabis Research (San Diego), and Columbia University (New York, NY) created a computer simulation to compare the cost of usual first-, second-, and third-line care with those supplemented with smoked cannabis. They modeled efficacy and adverse events based on clinical trial and other existing study data, and derived cannabis cost from retail market pricing.

Read the full press release here


Smoking weed: When is someone too high to drive?

NBC News, January 3, 2019

It used to be the stuff of stoner comedies and “Just Say No” campaigns. Today, marijuana is becoming mainstream as voters across the country approve ballot questions for legalization or medical use.

In response, state governments are testing ways to ensure that the integration of this once-illicit substance into everyday life doesn’t create new public health risks. These efforts are sparking a difficult question: At what point is someone too high to get behind the wheel?

The answer is complicated. Brain scientists and pharmacologists don’t know how to measure if and to what extent marijuana causes impairment.

Read the rest of the story here


What’s behind the rise in cannabis-infused products?

Alex Hannaford, BBC, November 22, 2018

There’s vape oil, pain-relief cream, patches, sweets (gummy bears, sour snakes, rainbow bites – take your pick), capsules and compounds.

Cannabidiol, or CBD as it’s better known – a naturally occurring extract of the cannabis sativa plant – is now so ubiquitous in the US, you’d be forgiven for thinking there are few places it's not available and few ailments it cannot treat.

Users say they take it for everything from muscle aches and anxiety to arthritis, epilepsy and Post Traumatic Stress Disorder.

And let’s not forget Fido. There’s CBD oil for him too – with added bacon flavour.

Read the article here


Cannabis 101: A Q&A with UC San Diego Health’s cannabis experts

Gabrielle Johnston, MPH, UC San Diego Health, October 30, 2018

It seems like everywhere you turn cannabis or cannabis derivatives can be found. From ingredients in coffee and smoothies to being marketed as medicine, a cannabis craze seems to be sweeping the country. Since 2000, UC San Diego School of Medicine’s Center for Medicinal Cannabis Research and its affiliated researchers have been studying marijuana and its derivatives, their effects on mind and body and their therapeutic potential.

We asked experts to cut through the hyperbole and haze to answer some burning questions.

Read the Q&A here


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