Cannabis May Be Useful Postoperatively, But Many Questions Remain

Cannabis may help curb postoperative symptoms such as pain, nausea and insomnia; however, the appropriate dosage, frequency, route of consumption and treatment duration are unknown, and there are no standards for measuring the therapeutic components, researchers say.

"The bottom line is that the majority of post-surgical pain relief is currently accomplished by narcotics (side effects of sedation, addiction), benzodiazepines (side effects of respiratory suppression and addiction), and non-steroidal anti-inflammatories (side effects of ulcer disease and kidney failure)," Dr. Yuman Fong of City of Hope Medical Center in Duarte, California, told Reuters Health by email.

"Cannabis and its derivatives offer the potential of non-addictive, non-respiratory suppressing relief from pain and anxiety," he said. "They also represent a possible solution to sleep cycle disturbances that are so common in patients after surgery."

Nonetheless, adds coauthor Dr. Camille Stewart of the University of Colorado School of Medicine in Aurora, who was a surgical oncology fellow at City of Hope when the research was done, "Medical cannabis is treated differently than any other substance in the U.S. believed to have therapeutic potential," in that its legal status varies from state to state.

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"In states that allow providers to recommend medical cannabis, clinicians are not able to be specific in their recommendations regarding the way in which cannabis is used by their patients - i.e., the amount, the way it is ingested, the frequency of ingestion," she said by email.

"Medical marijuana is not at the pharmacies our patients usually go to for other prescription medications," she added. "Many cannabis products are mislabeled and there are limited options for obtaining cannabis products with certified purity."

In their review of the current status of cannabis in the U.S., published in JAMA Surgery, Drs. Fong and Stewart offer recommendations for surgeons. These include:

- Patients should not inhale the products of combustion prior to undergoing surgery;

- Smoking of any kind should not be endorsed;

- In light of concerns about e-cigarette or vaping product use-associated lung injury (EVALI) attributed to vitamin E acetate in cannabis preparations intended for vaporization, the safest consumption method is oral or submucosal;

- Given the potential to affect induction of anesthesia and the P450 system, oral or submucosal consumption of cannabis products should be held for 10 days prior to surgery (based on the 24-36 hours half-life of dronabinol and 56-61 hours half-life of cannabidiol); and

- Patients may resume consumption of cannabis products when other oral home medications are resumed.

"The risks of cannabis use as they relate to surgical complications are unknown, but long-term benefits appear to outweigh risks primarily for patients with cancer-related pain and nausea," they note in the review. "In the symptomatic treatment of surgical patients, cannabis offers the possibility that pain, anxiety, and insomnia may be treated with less use of opioids and benzodiazepines. However, rigorous studies are necessary to definitively prove value."

Dr. Lawrence Weinstein, Chief Medical Officer of American Addiction Centers, commented in an email to Reuters Health, "The findings make sense when combined with what we already know about the use of cannabis perioperatively. Just as opioid use prior to a surgical procedure can lead to an exaggerated pain response post-surgery, there is evidence that cannabis use prior to surgery can produce the same result. It is exceedingly unlikely that an individual would initiate cannabis use immediately after a surgical procedure, so it would follow that those who used cannabis preoperatively would use cannabis postoperatively, and as a result, experience the increased pain that can occur in that situation."

"There are myriad differences and distinctions in cannabis plants, the products produced from them, genetic variation and manipulation of the plant, components such as cannabinoids and terpenes, (and) method of delivery," he said. "Arriving at a clinically approved and accepted dosage would be an arduous task."

—Marilynn Larkin

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