By Roger Chriss, PNN Columnist
This has been a challenging month for supporters of medical cannabis, with two professional pain societies – the Australian and New Zealand College of Anaesthetists and the International Association for the Study of Pain (IASP) both releasing statements saying they do not endorse the use of cannabis to treat pain.
IASP’s position statement came after a two-and-a-half-year review of cannabis studies by researchers at the University of Bath’s Centre for Pain Research, who found little evidence to support the use of cannabis for pain control.
“Cannabis seems to attract strong opinions. If ever a field needed evidence and a rigorous scientific opinion it is this one. For many this will be an unpopular conclusion, but we need to face up to the fact that the evidence is simply lacking. Science is not about popularity but keeping people safe from false claims,” said Professor Christopher Eccleston, Director of the Centre for Pain Research
Eccleston and his colleagues published their findings in a series of 13 articles in IASP’s journal PAIN. They found that many cannabis studies had too few participants, tested a single-dose exposure in a laboratory, or the trials only lasted a couple of weeks. Such work can justify further research, but not the clinical use of a drug by patients, which requires long-term studies of safety and efficacy.
“Cannabis, cannabinoids, and cannabis-based medicines are becoming an increasingly popular alternative to manage pain. However, our review shows that there is limited evidence to support or refute their use for the management of any pain condition. The studies we found were poor quality and the evidence was of very low-certainty,” said Dr. Emma Fisher of the University of Bath.
Although cannabis has been used for thousands of years for pain and other conditions, there are few good quality studies to support its use, as anesthesiologist Abdul-Ghalliq Lalkhen, MD, notes in his new book, “An Anatomy of Pain.”
“There have so far been only twelve randomized controlled trials on cannabis in the past five years, and most of these studies have indicated that cannabinoids are not effective in the management of neuropathic pain,” wrote Lalkhen.
Even when cannabis studies are conducted, they often have disappointing results. Zynerba Pharmaceuticals had high hopes for developing CBD drugs and a transdermal CBD skin patch, but quietly dropped them after disappointing clinical trials.
“Zynerba’s drugs have struggled mightily in the clinic, missing key endpoints and sometimes failing to show dose-dependent responses. Plans for an epilepsy and osteoarthritis drug fell away with clinical failures in 2017. A year later, so did a patch that was meant to deliver their THC through the skin,” Jason Mast reported in Endpoints News.
The lack of good evidence was noted by the Food and Drug Administration when it recently warned two companies illegally marketing over-the-counter CBD products for pain relief:
“It’s important that consumers understand that the FDA has only approved one drug containing CBD as an ingredient. These other, unapproved, CBD products may have dangerous health impacts and side effects. We remain focused on exploring potential pathways for CBD products to be lawfully marketed while also educating the public about these outstanding questions of CBD’s safety,” said FDA Principal Deputy Commissioner Amy Abernethy, MD.
Even when high-quality, placebo controlled trials are conducted, they often fail to replicate the results of lower-quality studies. For instance, cannabis is often touted for post-traumatic stress disorder (PTSD). But a recent clinical trial of cannabis for PTSD found it worked no better than a placebo.
“No active treatment statistically outperformed placebo in this brief, preliminary trial. Additional well-controlled and adequately powered studies with cannabis suitable for FDA drug development are needed to determine whether smoked cannabis improves symptoms of PTSD,” researchers concluded.
The American Medical Association takes a similar view. “Scientifically valid and well-controlled clinical trials conducted under federal investigational new drug applications are necessary to assess the safety and effectiveness of all new drugs, including potential cannabis products for medical use,” the AMA said.
Cannabis users deserve high-quality research. And the medical community deserves respect for not endorsing cannabis before the evidence base is well established. Arguing over low-quality studies does not have the persuasive power of a high-quality clinical trial.
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.