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.

Study to Examine Possible Effects of Cannabis Compound for Common Movement Disorder

Press Release, UC San Diego Health, September 18, 2018

Researchers at University of California School of Medicine are preparing to launch a novel clinical trial to examine the safety, efficacy and pharmacological properties of cannabis as a potential treatment for adults with essential tremor (ET). Currently, ET is treated using repurposed medications originally developed for high blood pressure or seizures. Surgery is another option.

Scheduled for early 2019, the phase I/II trial will assess efficacy and tolerability of an oral cannabis formulation comprised of cannabidiol (CBD) and low-dose tetrahydrocannabinol (THC). Researchers say it will be the first time this combination has been studied for treatment of ET.

“This study will provide key insights,” said Fatta Nahab, MD, neurologist at UC San Diego Health and associate professor of neurosciences at UC San Diego School of Medicine. “If found to be safe and effective, cannabis would not only serve as an exciting new addition to the limited treatment options currently available for patients with ET, but it might also provide scientists with new insights on essential tremor.”

Read the full press release here


Cannabis for Chronic Nerve Pain: Mechanism Revealed?

Damian McNamara, Medscape, September 7, 2018

New imaging findings show how tetrahydrocannabinol (THC), the psychoactive component of cannabis, works in the brain to effectively treat chronic neuropathic pain.

Results of a small randomized, double-blind, crossover trial show that THC-induced pain relief was associated with reduced functional connectivity between the anterior cingulate cortex (ACC) and the sensorimotor cortex.

"The main message of this paper is that THC, the psychoactive component in cannabis, does seem to exert a beneficial effect on proven chronic nerve pain.

This effect seems to involve a breakdown in functional connectivity between brain regions that process different dimensions that construct the experience of pain," study author Haggai Sharon, MD, who leads the Consciousness & Psychopharmacology research team at Sagol Brain Institute, Tel Aviv, Israel, told Medscape Medical News.

Read the article here


Cannabis Compound May Help Reduce Symptoms of Psychosis

Bob Curley, Healthline, September 5, 2018

Chronic marijuana use has been linked to increased risk of psychiatric problems. There’s even a name for the condition — cannabis-induced psychosis (CIP).

A new study, however, shows that a nonpsychoactive compound found in cannabis seems to reduce abnormal brain functions associated with psychosis, which includes diseases such as schizophrenia and bipolar disorder.

Researchers at King’s College London report in the journal JAMA Psychiatry that a single dose of cannabidiol (CBD) could someday be an effective alternative to the antipsychotic drugs in use since the 1950s.

These include Thorazine and Haldol, which have limited effectiveness and can cause serious side effects.

“It’s clear that the existing drugs have provided a lot of patients with schizophrenia the ability to function in society, but they’re not a cure,” Dr. Igor Grant, chair of the department of psychiatry at the University of California at San Diego School of Medicine and director of the school’s Center for Medicinal Cannabis Research, told Healthline.

Read the story here


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