Grand Junction, CO—Hospital pharmacists might want to take note: Patients who regularly use cannabis might require much more sedation when undergoing medical procedures.

A recent report in the Journal of the American Osteopathic Association suggests that could be as much as double the dosage.

To reach that conclusion, researchers in Colorado—where adults can legally possess an ounce of marijuana—examined medical records of 250 patients who received endoscopic procedures after 2012, when the state legalized recreational cannabis.

Results indicate that patients 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. That included common screening procedures, such as colonoscopy.

“Some of the sedative medications have dose-dependent side effects, meaning the higher the dose, the greater likelihood for problems,” explained lead researcher Mark Twardowski, DO, of Western Medical Associates in Grand Junction. “That becomes particularly dangerous when suppressed respiratory function is a known side effect.”

Twardowski raised concerns about lack of research on adverse effects of cannabis, pointing out, “Cannabis has some metabolic effects we don’t understand and patients need to know that their cannabis use 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 notes that anecdotal information from anesthesiology colleagues suggests that regular cannabis users not only need higher dosages for general anesthesia but also appear to have higher rates of postoperative seizures. Emergency-medicine clinicians, meanwhile, have reported many patients complaining of chronic nausea after regular use of the drug, he adds.

Based on those reports, Twardowski and his colleagues embarked on their study.

Adding specific questions regarding cannabis use to patient-intake forms is the first step to acquiring useful information that influences patient care, according to researchers, who added, “Determining cannabis use before procedural sedation can be an important tool for planning patient care and assessing both medication needs and possible risks related to increased dosage requirements during endoscopic procedures.”

“This study really marks a small first step,” says Dr. Twardowski. “We still don’t understand the mechanism behind the need for higher dosages, which is important to finding better care management solutions.”

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