The sale and consumption of cannabis will soon be legal in Canada. But a recent Canadian study nevertheless states that the risks associated with therapeutic cannabis, already authorized in the country, could outweigh the benefits in the treatment of several diseases.
In a few months, Canada will legalize the sale and consumption of cannabis, a campaign pledge by Prime Minister Justin Trudeau. For now, many shops and pharmacies already offer cannabis for medical use. Soon, recreational use will also be tolerated. No wonder cannabis has a good reputation in Canada. While Canadians are attached to certain principles, such as not crossing the road outside the crosswalk, the majority of them have no complaints about the legalization of cannabis. In short, marijuana is to Canadians what Bordeaux is to the French. A cultural drug.
The disadvantages of medical cannabis in Canada
Yet according to the document titled “Simplified recommendations for prescribing medical cannabinoids in primary care “, there is little evidence on the benefits of medical cannabis. The real advantages are often outweighed or even negated by the disadvantages. These new medical recommendations suggest that Canadian general practitioners should take a specialist second opinion before prescribing medical cannabis.
“Even though enthusiasm for medical cannabis is very strong among some patients, good quality medical research has not demonstrated such a benefit,” said Mike Allan, director of Evidence-Based-Medicine at the University of Alberta and project leader for recommendations. These recommendations were developed after a thorough analysis of published clinical trials on medical cannabis and were overseen by a committee of 10 experts, assisted by 10 other specialists and 40 other doctors, pharmacists, nurse practitioners, nurses and patients. The review focused on the benefits of cannabinoids used for the treatment of pain, spasticity, nausea and vomiting, as well as their side effects and toxicities.
According to the researchers, in most of the claimed indications for cannabinoids, the number of randomized studies testing medical cannabis is extremely limited, if not entirely absent. The size and duration of the existing studies are also very limited, which clearly limits their scientific scope. “Usually we’re talking about a single study and the methodology is very bad,” Allan said. “For example, there aren’t any studies for the treatment of depression. On anxiety, there’s a single study of 24 patients suffering from social anxiety in which half received a single dose of a cannabis derivative (…). This is very insufficient to determine whether lifelong treatment of generalized anxiety disorder is reasonable “.
Is medical cannabis effective?
According to the recommendations, the level of evidence is acceptable for the use of medical cannabinoids only in a handful of very specific diseases. These include chronic neuropathic pain (pain of neurological origin), palliative treatment of cancer pain, spasticity associated with multiple sclerosis (or spinal cord injury), as well as nausea and vomiting. secondary to chemotherapy. Even in these specific cases, the assessed benefits were found to be generally minor.
For neuropathic pain, 30% of patients who take a placebo have moderate improvement in their pain compared to 39% of those who take medical cannabinoids. In patients with spasticity, 25% of patients on placebo had a moderate improvement, compared to 35% on medical cannabis. The use of medical cannabis appears to be more effective in the management of nausea and vomiting under chemotherapy. Slightly less than half of patients using cannabinoids no longer experience nausea and vomiting, compared to only 13% of patients on placebo.
Non-negotiable side effects
“Medical cannabinoids should therefore be considered only in a handful of conditions where there is sufficient evidence and only after the patient has tried standard treatments,” Allan adds. associated smoking, we also recommend that pharmaceutical cannabinoids be tried first, before smoking medical marijuana ”.
While the evidence supporting the effectiveness of medical cannabinoids is limited, side effects are frequent and regular. About 11% of patients are unable to tolerate medical cannabinoids, compared to 3% of patients with placebo. The most common side effects are sedation (50% vs. 30% on placebo), dizziness (32% vs. 11% on placebo) and mental confusion (9% vs. 2% on placebo).
Mixed reviews
“These recommendations are not going to satisfy some people, especially those who have a partisan view in favor of medical cannabinoids,” Allan said. He added that those who oppose the use of cannabinoids for medical treatment may also be disappointed that the recommendations consider medical cannabinoids in a small number of specific cases. “Others, who think cannabinoids are very effective and safe, might feel frustrated that the recommendations do not call for their use sooner or in a wider range of diseases.”
But the main problem, experts say, is the dire lack of good quality studies of medical cannabis. “Better quality research is badly needed: randomized controlled trials that follow large numbers of patients for long periods of time. If we had that, it could change our outlook and change our recommendations.”
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