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 that number had grown to over 377,000. Recent work by our group has shown that there are many Canadians out there who use cannabis for medicinal purposes without medical authorization, which means the real 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, sleep disorders, seizure disorders, anxiety and other psychiatric conditions, and multiple sclerosis.

Upon medical approval, patients are given permission to access therapeutic cannabis products in general, not as a prescription for a specific drug with a specific dose, treatment regimen, and route of administration. One could imagine that such widespread use is based on evidence from high quality clinical trials, but unlike other regulated medicines, medical cannabis is widely available due to legal challenges rather than empirical evidence that the benefits outweigh the harm. There is widespread agreement that more research is needed on medical cannabis, especially randomized controlled trials, the gold standard for determining the effectiveness of therapeutic interventions.

Although any adult in Canada with internet access and a credit card can buy medical cannabis and have it delivered to their home, current government regulations have made it next to impossible for Canadian researchers to conduct clinical trials with these products. This is because Health Canada is asking a much higher bar for evaluating cannabis products in studies than it is for selling them to patients.

Every cannabis product used in clinical trials must be certified to meet exacting production standards called Good Manufacturing Practices (GMP), just like traditional pharmaceutical drugs. In other words, cannabis used in trials must be practically identical from batch to batch. This is a challenge for a herbal product and a higher standard than Health Canada requires for the manufacture of cannabis products. In addition, cannabis products used in randomized trials must contain preclinical data showing that the specific product being studied does not pose a cancer risk or harm to a developing fetus. Such tests are both expensive and time consuming and have not been performed by Canadian companies because Health Canada allows medicinal cannabis to be sold to patients for certain products without this information.

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

The consequences were not surprising. In 2019, the Canadian Institutes for Health Research, Canada’s national funding agency for medical research, funded nine randomized trials of medical cannabis. Two years later, none of these studies began enrolling patients. This is because no investigator in Canada has been able to find products that meet Health Canada requirements.

Canadian researchers are understandably frustrated. An open letter signed by more than 200 Canadian researchers has been sent to Health Canada to remove these critical barriers to medical cannabis research. A sensible solution is to have Health Canada-approved medical cannabis products that are commercially available through randomized trials. That said, if a medical cannabis product is good enough for Canadians to sell and consume, it should also be acceptable to study whether it works. Slower and more complicated options reduce the specificity of the preclinical data requirements or encourage a range of pre-approved medical cannabis products that are representative of the market.

Meanwhile, research in randomized trials into whether medical cannabis is effective or whether the benefits outweigh the harm is on the verge of stalling in Canada. These regulatory requirements hinder scientific studies, and more importantly, the evidence gaps adversely affect doctors and patients. As Health Canada revises its requirements for randomized trials of medical cannabis, it will determine whether the use of cannabis for therapeutic purposes in Canada is determined by marketing and anecdote or by evidence.

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