Regular Cannabis Users Need 220 Percent More Sedatives for Medical Procedures Than Nonusers

People who regularly use cannabis need a 220 percent higher dose of sedatives during medical procedures, according to a new study.

Researchers in Colorado, where marijuana was legalized in 2012, assessed the medical records of 250 patients, including 25 who regularly used cannabis. Between 2015 and 2017, those patients had an endoscopy, a procedure in which medics use a camera to look inside the body.

Patients who used cannabis every day or every week needed a 220.5 percent higher dose of the drug propofol during sedation, compared with those who didn't, the data showed. They also needed 14 percent more fentanyl and 19.6 percent more midazolam. The findings were published in The Journal of the American Osteopathic Association.

Tetrahydrocannabinol, an ingredient in the plant, is known to interact with the cannabinoid receptors in the body, and that could affect how drugs such as opioids and benzodiazepines interact with them.

As more and more states legalize pot for recreational use, the use of cannabis in the U.S. has spiked by 43 percent between 2007 and 2015. Researchers are working to understand the health effects from this change.

The authors noted that their study was limited because of the small sample size and because they used retrospective medical records. Also, it relied on patients being honest about their cannabis use. Because a stigma is associated with the drug, individuals may have underreported.

Mark Twardowski, a doctor of osteopathic medicine and lead author of the study, told Newsweek, "The study opens our eyes to the hidden effects of cannabis. Even though it is now legal in many states and some countries, it is still a substance that has real and meaningful effects on the human body that at this point are poorly understood and warrant caution."

The interactions between cannabis and commonly used medicines "are extremely important and yet have not been previously investigated to any significant extent," he added.

"We were surprised by the extent and consistency of the effect that cannabis use had on the increasing doses needed to achieve adequate sedation for the procedures. This effect was noted for all three of the common sedation medications used. This is particularly interesting, as the medications are from three different medication classes," he said. "Cannabis is very poorly studied, and this investigation begins to point out some of the challenges that chronic cannabis use poses."

Asked whether there is a safe amount of cannabis to use, Twardowski said, "No data exists to my knowledge as to whether a 'safe dose' of cannabis has been determined. Those who choose to use cannabis regularly certainly need to be aware that the use may have effects on their medical care, including the doses of medications required to maintain comfort for procedures.

"These increased doses may potentially carry risks. The extremely long half-life of THC in the body suggests that the ability to reverse the tolerance may take quite some time, possibly even months."

The study was published the same week as a separate piece of research investigating the effects of cannabis use during pregnancy. Using cannabis while pregnant to ease morning sickness could damage the brain of a fetus, warned scientists who had studied the effects in rats.