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Experts say more research is needed on the topic. Getty Images

People who use cannabis regularly may need up to two times more sedation if they undergo a medical procedure compared to those who don’t use the drug regularly, a new study claims.

But the study’s research methods are under scrutiny, as other experts say there’s not enough credible evidence to make a correlation between cannabis use and more sedation.

A report in The Journal of the American Osteopathic Association looked at records from 250 people from Colorado undergoing an endoscopic procedure between 2015 and 2017. They were randomly chosen from a pool of 1,158 cases. In 2012, the state legalized recreational cannabis.

In the study, patients who reported sporadic use or topical use — usually consisting of cannabidiol (CBD) oils or ointments — were considered non-users. Those who reported not using at all were also non-users. Users were defined as those who self-reported using cannabis — by smoking or ingesting edibles — on a daily or weekly basis.

Out of 250 people, 25 were regular cannabis users. They received 19 colonoscopies, two esophagogastroduodenoscopies (EGDs), and four colonoscopy/EGDs. Of 225 non-users, 180 had colonoscopies, 27 EGDs, and 18 had colonoscopies/EGDs.

Those who smoked or ingested cannabis on a daily or weekly basis required 14 percent more fentanyl, 20 percent more midazolam, and 220 percent more propofol to achieve optimum sedation for the aforementioned routine procedures.

The concern about giving patients more sedation is that some of the medications pose a greater likelihood for problems the higher the dose gets.

“The dangers of progressively higher doses of sedatives and opiates is that of respiratory suppression. The other potential risk of some of the medications is low blood pressure,” Dr. Mark Twardowski, an osteopathic internal medicine physician and lead author of the study, told Healthline.

Twardowski said it’s unclear what the mechanism is that seems to make cannabis users require more sedation.

“We and others suspect that the effect lies at the receptor level — possibly through some sort of down regulation, but the specifics are not known,” Twardowski said.

Physicians who regularly work with sedation have a rough idea how much is used for the average person dependent on different procedures. They recognize when a patient is responding more slowly and less vigorously to usual sedation doses, he said.

Using more sedation poses health risks to the patient, and can create an increased cost burden when more medication must be used.

Dr. Yury Khelemsky, an associate professor of anesthesiology, perioperative and pain medicine, and neurology at the Icahn School of Medicine at Mount Sinai, questioned several aspects of the study. He noted that Twardowski lacks specific expertise in the anesthesiology field, as he is a primary doctor.

“The study had many critical flaws, which render it useless,” Khelemsky told Healthline. “Overall, the conclusion that cannabis use has anything to do with increased doses of sedation cannot be supported or disputed by looking at this data.”

He noted that 16 percent of cannabis users underwent longer procedures compared to 8 percent of non-users, which could be a reason why cannabis users needed more medication.

While it may be true that some cannabis users underwent longer procedures, that’s largely attributed to the fact that accomplishing sedation took more time. The procedure is begun once the patient is adequately sedated, and if they become uncomfortable during the procedure, it’s paused until comfort is reestablished, which would lengthen the procedure.

If patients were using other drugs such as methamphetamines, that could alter the dose of medication required to sedate the patient, Khelemsky said. “This was not accounted for in the study design or analysis. Cannabis users are also more likely to use other illicit drugs, this was also not accounted for,” Khelemsky explained.

He also questioned if the nurses or doctors knew ahead of time which patients used cannabis. According to the report, information on drug use was collected, but the endoscopist wasn’t aware of a patient’s cannabis use when performing procedures, Twardowski said.

Khelemsky also contends that self-reporting drug use, especially when it’s not done anonymously, produced unreliable data.

“As of now, there is no good evidence that cannabis use alters anesthetic dosing,” Khelemsky said.

Twardowski said self-reporting is never 100 percent accurate, but his team felt that people would be more likely to report accurately due to legalization in the state.

Dr. James Lozada, an anesthesiologist at Vanderbilt University Medical Center, said weight can play a role in whether or not a patient requires more of a sedative, especially propofol. Anxiety is another factor that can affect the levels of medication needed, and many people take cannabis for anxiety. Those factors aren’t reflected in the research.

“We don’t yet have good research that says regular cannabis users require more medicine for anesthesia,” Lozada said. “To truly assess something like this, blood levels need to be drawn to compare groups… because it’s not just that cannabis is there, it’s also in what level.”

“While this study is interesting, important details are missing which prevent us from drawing meaningful conclusions,” Lozada added.

He noted research released this month about anesthesia and children who take medicinal marijuana for seizures. The authors recommend using caution when administering sedatives and opioids, as the effect may be additive and lead to excess sedation.

Dr. Jonathan H. Waters, chief of anesthesiology at UPMC Magee-Women’s Hospital in Pittsburgh, said many drugs increase the need for higher doses of anesthesia.

“For instance, regular alcohol use increases need,” he told Healthline. “So, it’s not really that surprising that cannabis has a similar effect.”

Twardowski said the study is an initial look into this topic, and the findings certainly seem to reflect a need for increased dosage of sedation in cannabis users.

“This is strong evidence, but we encourage and invite further research on this topic,” Twardowski said.

Twardowski is concerned about how cannabis users may respond to sedation, as there’s a lack of research into cannabis and sedation as more states continue to legalize it.

The good thing about trying to understand the impacts of cannabis use is that more patients may be forthcoming about their use, he added.

Twardowski hopes his study will bring more awareness about the effects that cannabis has on the efficacy of some medications. He also hopes it sheds more light on whether or not cannabis has effects on medications used for anxiety and psychiatric issues, as well as opiates and pain control. He hopes to find out if the effects may be related to tetrahydrocannabinol (THC) or CBD.

“This awareness should help to better prepare physicians to deal with the patient’s sedation needs,” he said.

His team plans a follow-up study to look at the different requirements for sedation and anesthesia, as well as post-procedure pain management for cannabis users and non-users.

“More research is needed to determine if a true association exists,” Lozada added.