Pharmacy News

Should medical cannabis be used to treat chronic pain?

According to CDC, people most often cite pain management as their reason for using medical cannabis in the United States. But according to a new clinical practice guideline published by Busse and colleagues in the September 2021 issue of BMJ, there is weak evidence to support the use of non-inhaled medical cannabis or cannabinoids for chronic pain. The recommendation is based on a robust analysis of results from 32 randomized controlled clinical trials.

While Busse and colleagues’ guideline does not recommend the use of medical cannabis or cannabinoids in chronic pain as the standard of care, the authors do suggest offering patients a trial of non-inhaled medical cannabis or cannabinoids if standard care and management for moderate to severe chronic pain is insufficient.

“Smoking cannabis is not advised because of the adverse [pulmonary] effects of smoking,” said Edeltraut Kröger, BPharm, PhD, a research scientist at Centre d’excellence sur le vieillissement de Québec, who did not contribute to the guideline.

The guideline recommends that therapeutic trials of medical cannabis should start with low doses, gradually increasing the dose and THC level based on clinical response and tolerability. Busse and colleagues suggest a starting dose of 5 mg cannabidiol (CBD) twice daily, increasing 10 mg every 2 to 3 days to a 40 mg maximum daily dose. If the response is insufficient, they recommend adding 1 mg to 2.5 mg tetrahydrocannabinol (THC) per day and titrating 1 mg to 2.5 mg every 2 to 7 days for a maximum of 40 mg/day. Prior cannabis use should be taken into consideration.

“I would advise [patients] to talk to their doctor about their wish to try medical cannabis so their doctor can follow up on what they use, how often they use it, and positive or adverse effects they perceive,” said Kröger, who is also an adjunct professor at the Faculty of Pharmacy, Université Laval and the Department of Medicine, McGill University in Quebec, Canada.

The researchers found high-quality evidence to support the potential benefits of medical cannabis use on improved sleep quality and physical function, but the review found moderate-quality evidence for a reduction in pain.

According to the research team, serious adverse effects are unlikely to occur in patients taking medical cannabis, with the risk of fatal overdose nearly nonexistent.

Based on the studies reviewed, the adverse effects—in order of severity—experienced by trial participants include cognitive impairment, vomiting, impaired attention, drowsiness, dizziness, nausea, and diarrhea. The most common non-serious adverse effect was dizziness.

Clarissa Chan, PharmD, contributing writer

For the full article, please visit for the December 2021 issue of Pharmacy Today. 

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