Proposed Guideline Urges Caution Prescribing Cannabis in Canada

Proposed Guideline Urges Caution Prescribing Cannabis in Canada

A proposed guideline focusing on the use of cannabinoid medical products says there is some evidence they benefit patients with chemotherapy-induced nausea and vomiting, which is particularly relevant for patients with lymphoma or blood cancers.

However, for most conditions, there is a significant lack of evidence that medical marijuana benefits patients, leading University of Alberta researchers to recommend against medical cannabinoid use in general, until further research is conducted.

The study “Simplified Guideline for Prescribing Medical Cannabinoids in Primary Care” was published recently in Canadian Family Physician.

While the use of medical marijuana has increased significantly in the past few years, it is still unclear of the benefits, if any, to patients.

So, researchers weighed the risks and benefits of cannabis medicinal products in four different areas —  pain, nausea and vomiting, spasticity, and adverse events. Based on the findings, they developed  a guideline to help primary care physicians decide when to recommend such treatments to their patients.

Their research found some evidence that these products benefit patients with neuropathic pain, palliative and end-of-life pain, chemotherapy-induced nausea and vomiting, and spasticity — an increase in muscle tone that causes involuntary muscle stiffness — in patients with multiple sclerosis or spinal cord injury.

Their guidelines say that investigators could consider medical cannabinoids for treating refractory chemotherapy-induced nausea and vomiting (CINV), with the following considerations:

  • A discussion has taken place to inform patients of the risks and benefits of medical cannabis for CINV;
  • Patients have had a reasonable therapeutic trial of standard therapies and continue with persistent CINV;
  • Cannabis products are adjuncts to other prescription medicines.

In two situations, however, researchers strongly recommend against medical cannabis — or nausea and vomiting during pregnancy (particularly due to lack of evidence and unknown harms), and as first- or second-line therapy for CINV (mostly due to comparisons with first-line agents and known harms).

If considering medical cannabinoids, the panel recommends nabilone. However, the panel recommends against nabiximols and medical marijuana (smoked, oils, or edibles) as the latter are inadequately studied.

In cases of CINV, patients taking medical cannabinoids mostly reported central nervous system effects (60% vs. 27% in the placebo group), sedation effects (50% vs. 30% in placebo), speech disorders (32% vs. 7%) and dizziness (32% vs. 11%). However, 5% to 6% reported symptoms of dissociation or psychosis (versus 0 in placebo) or hallucinations (versus 0), which are two commonly cited “fears” for trying medical cannabis products.

Importantly, weighing these considerations, the researchers believe that medical cannabinoids could be considered, with caution, only for CINV refractory to current anti-nasuea and vomiting therapies.

“Better research is definitely needed — randomized control trials that follow a large number of patients for longer periods of time,” Mike Allan, said in a press release. Allan is director of evidence-based medicine at the University of Alberta and project lead for the guidelines project.“If we had that, it could change how we approach this issue and help guide our recommendations.”

At the moment, the guideline is a proposal and researchers are seeking feedback before the final version is published.

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