A Penn State College of Medicine study found that cannabinoid-containing products may alter the effects of some prescription drugs, with the new results helping medical professionals make safe prescribing choices for their patients who use prescription, OTC, or illicit cannabinoid products.

A list of 57 medications that may not function as intended when used with medical cannabinoids, cannabidiol (CBD) oil, and medical or recreational marijuana was compiled by Kent Vrana, PhD, chair of pharmacology at Penn College of Medicine, and Paul Kocis, PharmD, RPh, CACP, a pharmacist at Penn State Health Milton S. Hershey Medical Center.

The medications have a narrow therapeutic index or are prescribed at specific doses, which are enough to be effective but not enough to cause harm, according to the study.

The researchers had to examine the prescribing information for 4 prescription cannabinoid medications to develop the list. This information included a list of enzymes in the body that process the active ingredients in those medications, which can include delta-9-tetrahydrocannabinol (THC) and CBD.

Further, the researchers compared the information against prescribing information from common medications using data available from regulatory agencies, such as the FDA, to identify where there may be overlap, also known as a drug-drug interaction, according to the press release.

The list contains a variety of drugs from heart medications to antibiotics and antifungals. The researchers said that medical professionals should also consider patient use of CBD oil products and medical and recreational marijuana when using or prescribing drugs on the identified list. Further, many of the products lack government regulation and there is little to no prescribing or drug-drug interaction information for those products, according to the study.

“Unregulated products often contain the same active ingredients as medical cannabinoids, though they may be present in different concentrations,” Vrana said in a press release. “The drug-drug interaction information from medical cannabinoids may be useful as medical professionals consider the potential impact of over-the-counter or illicit cannabinoid products.”

The researchers advise that patients be honest with their health care providers about their use of cannabinoid products, from OTC products to recreational marijuana. Vrana said that doing so can help ensure the safe and effective use of prescribed medications.

In addition to the 57 prescription medications that were identified with a narrow therapeutic index that is potentially affected by concomitant cannabinoid use, a comprehensive list of 139 medications that could have a potential drug-drug interaction with a cannabinoid is available online.

REFERENCE
Cannabinoids may affect activity of other pharmaceuticals. Penn State News. https://news.psu.edu/story/627290/2020/08/03/research/cannabinoids-may-affect-activity-other-pharmaceuticals#:~:text=HERSHEY%2C%20Pa.,State%20College%20of%20Medicine%20researchers.&text=The%20list%20contains%20a%20variety,medications%20to%20antibiotics%20and%20antifungals. Published August 3, 2020. Accessed August 4, 2020.