By Roger Chriss, Columnist
There is a tsunami of enthusiasm for medical cannabis. Rolling Stone is touting “medical pot” as the best hope to fight the opioid crisis. Newsweek has introduced the world to the “father of marijuana research” and even offered suggestions for using cannabis in holiday cooking.
But underlying all this cannabis coverage are confusing claims about the efficacy of medical marijuana for chronic pain and other conditions.
Although still in its infancy, the science behind medical cannabis is growing rapidly. ClinicalTrials.gov lists 139 research studies underway. PubMed.gov lists 5,615 articles about “medical cannabis” and over 25,000 articles about “marijuana.” By comparison, PubMed lists only 112 articles about kratom.
The results of these thousands of studies involving scores of medical conditions are mixed, with an extensive list and reviews of clinical studies available on Cannabis-Med.org.
The National Academy of Science released “The Health Effects of Cannabis and Cannabinoids” report in January 2017, stating that there is “evidence to support that patients who were treated with cannabis or cannabinoids were more likely to experience a significant reduction in pain symptoms.”
But a review article from September 2017 called "Cannabinoids in Pain Management and Palliative Medicine" concluded that public perceptions about the effectiveness of cannabis in providing pain relief “conflicts with the findings.”
"There is limited evidence for a benefit of THC/CBD spray in the treatment of neuropathic pain. There is inadequate evidence for any benefit of cannabinoids (dronabinol, nabilone, medical cannabis, or THC/CBD spray) to treat cancer pain, pain of rheumatic or gastrointestinal origin, or anorexia in cancer or AIDS," German and Canadian researchers reported.
This apparent contradiction is often a result of limited research findings. Studies on medical cannabis are usually small-scale, preliminary, methodologically poor and statistically underpowered, and thus of limited value for drawing general conclusions.
The biggest issue in many studies is the lack of a good placebo for marijuana, as described in a recent JAMA Internal Medicine article: “Many trial subjects can distinguish between active cannabis and placebo.” This means that blinding subjects to obtain unbiased results is difficult, which makes the findings insufficient to get FDA approval as a medication.
"Unfortunately, there are almost no uses of medical marijuana that have been subjected to the kind of rigorous testing you'd want for a pharmaceutical," says Dr. Kenneth Mukamal, associate professor of medicine at Harvard-affiliated Beth Israel Deaconess Medical Center.
But there is progress. As the JAMA Internal Medicine study noted, “Some of the strongest evidence is for neuropathic pain, spasticity associated with multiple sclerosis, and anorexia in the setting of serious illness.”
A recent phase III clinical trial supports this. Nearly 250 patients with moderate to severe neuropathic pain from multiple sclerosis saw “clinically relevant” reductions in pain intensity due to dronabinol, a synthetic marijuana derivative.
Marijuana Not Risk Free
Studies are also showing that medical cannabis is not risk-free. Some media reports state that there is no known instance of a fatal overdose involving marijuana. This is accurate, but fatal overdose is not the only measure of risk for a substance. Non-fatal toxicity, including cannabinoid hyperemesis syndrome (recurring nausea, vomiting and stomach pain), and other side effects are not trivial risks.
“Chronic effects of cannabis use include mood disorders, exacerbation of psychotic disorders in vulnerable people, cannabis use disorders, withdrawal syndrome, neurocognitive impairments, cardiovascular and respiratory and other diseases,” researchers warned in a 2014 article in the journal Current Pharmaceutical Design.
Research on the long-term effects of daily marijuana use is also limited. Fortunately, the National Institutes of Health is sponsoring major research on medical cannabis, including a 5-year study to see if medical cannabis reduces opioid use in adults with chronic pain. Similar efforts are underway at the UCLA Cannabis Research Initiative and elsewhere.
Therefore, it is premature to assume that medical cannabis is a thoroughly understood substance that will safely solve all chronic pain problems. Chronic painful conditions are complex, and the treatments that work for one condition may be contraindicated for another. Moreover, not everyone tolerates cannabis, just as not everyone tolerates NSAIDs or opioids. And a person’s medical condition and treatment plan may or may not be able to accommodate cannabis.
Medical cannabis has the potential to become another resource for pain management. It is showing promise for some neuropathic pain disorders, but does not seem to be as effective for visceral or rheumatic pain. In time, we will know how to use medical cannabis safely and reliably. But the present enthusiasm is running ahead of the science, and conclusions are preceding analysis.
Roger Chriss lives with Ehlers Danlos syndrome and is a proud member of the Ehlers-Danlos Society. Roger is a technical consultant in Washington state, where he specializes in mathematics and research.
The information in this column should not be considered as professional medical advice, diagnosis or treatment. It is for informational purposes only and represents the author’s opinions alone. It does not inherently express or reflect the views, opinions and/or positions of Pain News Network.