OU Researchers Study Effects of Cannabis on Sedation, Cancer Treatment Symptoms

As more patients report using cannabis in a state where medical marijuana is legal, researchers across several disciplines at the University of Oklahoma Health Sciences are uncovering insight into the effects of cannabis use on sedation and cancer symptoms.

In a journal publication in Gastrointestinal Endoscopy, University of Oklahoma College of Medicine physician-researchers found that, during an endoscopy, cannabis users were 77% more likely to require higher doses of the anesthetic propofol compared to non-users, and 57% more likely to need higher doses of the sedative midazolam. In addition, diphenhydramine, an antihistamine often used for extra sedation, was more commonly used to supplement moderate sedation in cannabis users versus non-users.

The study, which analyzed 976 patients, 21.5% of which reported using cannabis, is thought to be the most comprehensive of its kind. A total of 651 (66%) procedures were performed under moderate (conscious) sedation, and 335 (34%) procedures were performed under monitored anesthesia care, in which an anesthesia provider gives sedation and pain medication for minor procedures that do not require general anesthesia.

“It is important to understand how patients will respond to procedural sedation to plan and individualize care for each patient. Sedation can be challenging, and knowing ahead of time which patient may be more difficult to sedate can be instrumental in providing a comfortable, safe and successful procedure,” said Mohammad Madhoun, M.D., a professor of gastroenterology in the OU College of Medicine.

Faculty members in the OU College of Dentistry are also studying how cannabis use affects anesthesia. In a retrospective study of patients undergoing deep sedation or general anesthesia during outpatient oral and maxillofacial surgery procedures, cannabis users required more propofol, midazolam, ketamine and fentanyl than non-cannabis users, despite having a similar number of teeth extracted in about the same amount of time.

The study was published in the Journal of Oral and Maxillofacial Surgery. Lead author Fabio Ritto, D.D.S., M.D., Ph.D., is continuing the research.

“This is one of the challenges of performing sedation in chronic cannabis users,” Ritto said. “Understanding that this patient population requires higher doses of anesthetic medication allows providers to better prepare and assess whether these patients would be more safely managed in a hospital setting under full general anesthesia.”

Cannabis for cancer treatment symptoms

Other research has analyzed cannabis use among patients undergoing treatment for cancer who are seeking symptom relief. Of 267 adult patients at OU Health Stephenson Cancer Center who completed four surveys before, during and after treatment, 26% reported cannabis use in the past 30 days.

Participants most commonly reported using cannabis for pain, sleep, anxiety, and nausea and vomiting, and they reported the greatest perceived benefit for sleep, nausea and vomiting, headaches, pain, muscle spasms and anxiety. However, patients who used cannabis reported feeling worse physically and psychologically compared to those who did not use cannabis.

In a follow-up study, researchers analyzed physical symptoms and quality of life over time for patients who used cannabis versus those who didn’t. They were split into three groups: regular users, occasional users and non-users.

“We found that regular cannabis users had the most severe symptoms of the three groups, but it could be that people with more severe symptoms were more likely to use cannabis; that’s a limitation of the study,” said Darla Kendzor, Ph.D., co-director of the TSET Health Promotion Research Center and professor of family medicine in the OU College of Medicine. “But, from these findings, it’s not clear that cannabis is helpful in the context of cancer treatment, which suggests that patients and providers should use caution when making decisions about whether to use cannabis.”

Researchers were also concerned that, while edible cannabis was patients’ first choice, smoking cannabis was second, followed by vaping. “From what we know about smoking and its adverse impact on the lungs and other organs, this mode of cannabis use may be more harmful than other forms,” Kendzor said.

Ideally, researchers will one day conduct clinical trials that study the effects of commercially available cannabis products on cancer-related symptoms, although federal law currently limits such research.

“In the future, it would be interesting to conduct a trial in which half of the patients with cancer-related symptoms use cannabis and half don’t,” said study co-author Christina Henson, M.D., an associate professor of radiation oncology in the OU College of Medicine. “It would allow us to ask questions like, ‘Is the cannabis actually making people’s symptoms worse, or are patients with more severe symptoms looking for ways to treat their symptoms?’ Many people are using cannabis, and there’s not a lot known about it or how well it’s working.”