Cannabis users need more sedatives before routine medical procedures


US study finds regular users have poor responses to standard doses. Nick Carne reports.


In US states where marijuana smoking is legal, the biggest increase in users is among people aged over 26.

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US researchers have found that regular cannabis users require up to 220% higher dosages of sedatives in medical procedures. They don’t yet fully understand why, but are concerned about a possible rise in adverse side effects.

A team of physicians in Colorado, led by Mark Twardowski of Western Medical Associates Centre for Bone Health, examined medical records of 250 patients who received endoscopic procedures after 2012, when the state legalised recreational cannabis.

They found those who smoked or ingested cannabis on a daily or weekly basis required 14% more fentanyl, 20% more midazolam, and 220% more propofol to achieve optimum sedation for routine procedures, including colonoscopy.

“Some of the sedative medications have dose-dependent side effects, meaning the higher the dose, the greater likelihood for problems,” says Twardowski, an osteopathic internal medicine physician.

“That becomes particularly dangerous when suppressed respiratory function is a known side effect.”

Twardowski says cannabis has some metabolic effects that aren’t fully understood, and patients need to know that their use of it might make other medications less effective.

“We're seeing some problematic trends anecdotally, and there is virtually no formal data to provide a sense of scale or suggest any evidence-based protocols," he says.

Cannabis use in the US increased 43% between 2007 and 2015. An estimated 13.5% of the adult population used the drug during this period, with the greatest increase recorded among people 26 and older, according to the study.

The findings are published in the Journal of the American Osteopathic Association.

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  1. http://dx.doi.org/10.7556/jaoa.2019.052
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