WSU study: cannabis use could increase risk of harmful drug interactions

SPOKANE, Wash. — New research from Washington State University suggests using cannabis alongside other drugs could come with a significant risk of harmful drug interactions.

Scientists at WSU looked at cannabinoids, a group of substances found in the cannabis plant, and their major metabolites found in cannabis users’ blood. The researchers found that these substances can interfere with two families of enzymes that help metabolize a wide range of prescription drugs used to treat a variety of medical conditions. This can cause drugs’ negative effects to increase, their positive effects to decrease, or even unintended side effects such as toxicity or accidental overdose.

The researchers used manipulated kidney cells that allowed them to look at one single enzyme at a time. They then validated their results in human liver and kidney specimens in which many of the enzymes were present.

“If you have a kidney disease or you are taking one or more drugs that are metabolized primarily through the kidney and you’re also smoking marijuana, you could be inhibiting normal kidney function, and it may have long-term effects for you,” said Philip Lazarus, senior author on the papers and Boeing distinguished professor of pharmaceutical sciences.

The study’s authors say more research needs to be done, but one early takeaway is clear: it’s important to be careful when using cannabis with prescription drugs.

“Physicians need to be aware of the possibility of toxicity or lack of response when patients are using cannabinoids,” said Lazarus. “It’s one thing if you’re young and healthy and smoke cannabis once in a while, but for older people who are using medications, taking CBD or medicinal marijuana may negatively impact their treatment.”

The study’s funding came from the Health Sciences and Services Authority of Spokane County and the State of Washington’s Initiative Measure No. 502, which funds the university’s Alcohol and Drug Abuse Research Program.