Weighing Benefits, Harms of Cannabis

(from the April 2019 ACP Internist)

Marijuana use has risen, so internists need to understand its real risks as well as its potential clinical uses, such as for chronic pain, chemotherapy-induced nausea and vomiting, and multiple sclerosis spasticity symptoms.

By Mollie Frost

While lollipops may not be a health food, they aren't usually considered dangerous. However, in the recent case report of a 70-year-old man with stable coronary artery disease, eating a marijuana lollipop landed him in the ED with crushing chest pain, hallucinations, and a heart attack.

The pain began about 30 minutes after the man consumed most of the lollipop, which contained 90 mg of tetrahydrocannabinol (THC), the main psychoactive component of marijuana. (For many edible marijuana products, a dose of THC is generally considered to be 10 mg.) According to the case report, published in the February 2019 Canadian Journal of Cardiology, the patient ultimately recovered and was discharged with a diagnosis of non-ST-segment elevation myocardial infarction.

“What we think happened is that he had what we call a supply-demand type of heart attack,” said case coauthor and ACP Resident/Fellow Member Alexandra Saunders, MD, chief internal medicine resident at Saint John Regional Hospital in New Brunswick, Canada. “His heart rate increased, his blood pressure increased, and this was all the fear and anxiety that he had after taking the lollipop. There wasn't enough blood that was getting to his heart muscle itself.”

Recreational marijuana was legalized in Canada in October 2018, but just because a substance is legal doesn't mean that it is safe, she said. “People should consider the dose that they're getting and should talk with their health care provider about it before they consider trying it on their own,” said Dr. Saunders.

In the wake of a case like this, it may appear that the safety of marijuana has gone to pot. But some internists believe that the oft-misunderstood and under-researched plant, despite its downsides, may have real clinical potential for some patients.

Discussing the harms

In the U.S., reported marijuana use is growing. The proportion of adults who said they used marijuana in the past year rose from 4.1% in 2001-2002 to 9.5% in 2012-2013,according to a study published in December 2015 by JAMA Psychiatry. Most recently, in a 2017 survey of about 9,000 U.S. adults, 14.6% reported using marijuana in the past year, according to results published in September 2018 by Annals of Internal Medicine.

But it's also a sticky subject. Since 2012, 10 states have legalized cannabis for recreational use, and many more have medical marijuana programs. However, at the federal level, THC is still considered a Schedule I substance. Making matters more complicated, the 2018 U.S. Farm Bill effectively legalized hemp, defined as cannabis with less than 0.3% THC on a dry weight basis, by removing its Schedule I status.

Hemp's legalization has important implications for the use of other components of the plant, including cannabidiol (CBD), which does not have hallucinogenic or psychoactive properties. Both CBD and THC are active ingredients in FDA-approved drugs, and the FDA has said that despite the legalization of hemp, it remains illegal to introduce CBD products into the food supply or market them as dietary supplements without agency approval.

Still, people in states that have legalized recreational cannabis, such as Oregon and California, can readily purchase THC and CBD products. Even in states that have not legalized cannabis, CBD products abound. Because of the increased availability of cannabis products, even internists who do not wish to recommend them to patients have a role to play in discussing benefits and harms, experts said.

One of the most important actions a primary care clinician can take is to ask patients if they use any form of the plant, and for what reason (e.g., medicinal, recreational),said Tina M. Kaufman, PhD, PA-C, an assistant professor of preventive cardiology at Oregon Health & Science University in Portland. “Frequently, since it has been more broadly legalized, the question goes unasked because both providers and patients believe it is relatively benign: ‘It's natural,’” she said.

Read the full article in ACP Internist.

ACP Internist provides news and information for internists about the practice of medicine and reports on the policies, products, and activities of ACP.

Back to the May 2019 issue of ACP IMpact