Medical cannabis: Easy access for patients, but not for researchers


Medical cannabis is increasingly used by Canadians. In 2015, Health Canada reported 24,000 registered users, and by 2020 this figure had increased to over 377,000. Recent work by our group has found there are many Canadians who use cannabis for medical purposes without a physician authorization, meaning the true number is far greater. In Ontario alone, there are now more than 100 clinics specializing in medical cannabis for a range of conditions, including chronic pain, disordered sleep, seizure disorders, anxiety and other psychiatric conditions, and multiple sclerosis.

Following medical authorization, patients receive permission to access therapeutic cannabis products broadly, not as a prescription for a specific medication with a certain dose, regimen and route of administration. One might imagine that such widespread use is based on evidence from high-quality clinical trials, but unlike other regulated pharmaceuticals, medical cannabis is largely available because of legal challenges instead of empirical evidence that the benefits exceed the harms. There is widespread agreement that more research is needed on medical cannabis, specifically, more randomized controlled trials, the gold standard for determining effectiveness of therapeutic interventions.

Although any adult with access to the internet and a credit card can purchase medical cannabis in Canada, and have it delivered to their home, current government regulations have made it all-but-impossible for Canadian researchers to conduct clinical trials of these products. The reason is that Health Canada requires a much higher bar for cannabis products to be evaluated in trials than is needed for sale to patients.

Any cannabis product used in clinical trials must be certified to meet exacting production standards called Good Manufacturing Practices (GMP), the same as traditional pharmaceutical medicines. In other words, cannabis used in trials must be virtually identical from batch to batch, a challenge for a plant-based product and a higher standard than Health Canada requires for producing cannabis products. Furthermore, cannabis products used in randomized trials must have preclinical data showing that the specific product to be studied does not pose a risk of cancer or damage to a developing fetus. Such testing is both expensive and time-consuming and has not been undertaken by Canadian companies as Health Canada permits the sale of medical cannabis to patients without this information for specific products.

In other words, according to Health Canada’s regulations, the same products that are safe enough for consumption by hundreds of thousands of Canadians are not safe enough to be studied for effectiveness in randomized trials.

The consequences have been unsurprising. In 2019, the Canadian Institutes for Health Research, Canada’s national medical research funding agency, funded nine randomized trials of medical cannabis. Two years later, none of these trials have begun enrolling patients. The reason being that no study investigator has been able to locate products in Canada that meet Health Canada’s requirements.

Canadian researchers are understandably frustrated. An open letter, signed by more than 200 Canadian researchers, has been sent to Health Canada seeking redress of these critical barriers to research into medical cannabis. One reasonable solution is to permit Health Canada-approved medical cannabis products that are commercially available to be studied in randomized trials. That is, if a medical cannabis product is good enough for sale and consumption by Canadians, it should also be acceptable to study if it works. Slower and more complicated options are reducing the specificity of the preclinical data requirements or sponsoring a suite of pre-approved medical cannabis products that are representative of the market.

In the interim, research using randomized trials on whether medical cannabis is effective, or if the benefits exceed the harms, is close to a standstill in Canada. These regulatory strictures are stifling scientific study, and, more importantly, the gaps in evidence are adversely affecting clinicians and patients. How Health Canada revises its requirements for randomized trials of medical cannabis will determine whether use of cannabis for therapeutic purposes in Canada will be driven by marketing and anecdote, or by evidence.

Jason Busse and James MacKillop are the associate director and director of the Michael G. DeGroote Centre for Medicinal Cannabis Research at McMaster University and St. Joseph’s Healthcare Hamilton.



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