Research Identifies OTC Meds Commonly Involved in Drug-Drug Interactions

Over-the-counter (OTC) medication groups most frequently involved in drug-drug interactions over the last 50 years were non-steroidal anti-inflammatory drugs, food supplements, antacids, proton-pump inhibitors, H2-antihistamines, laxatives, antidiarrheal drugs, and herbal drugs. The findings were published online ahead of print in Therapeutic Drug Monitoring.

To increase awareness of drug-drug interactions involving OTC medications, Scherf-Clavel Oliver, PhD, of the University of Würzburg Institute for Pharmacy and Food Chemistry in Germany, conducted an extensive literature search on the topic. The researcher screened 408 relevant publications from 1972 through June 2021.

“The most significant finding,” Dr Oliver wrote, “was the lack of high-quality evidence for commonly acknowledged interactions. High-quality interaction studies involving different phenotypes in drug metabolism (cytochrome P450) and distribution (transporters) are urgently needed.”

Such research should include oral cancer medications and direct oral anticoagulants, Dr Oliver advised.

Otherwise, his investigation revealed that certain types of medication regimens—including antiretroviral, anti-infective, and oral anticancer therapies—are more prone to, or have more serious, drug-drug interactions.

“Second,” he added, “while most drug-drug interactions involve OTC drugs as the perpetrators, some prescription drugs (statins, phosphodiesterase-5 inhibitors) that currently have OTC status can be identified as the victims in drug-drug interactions.”

Reference:
Oliver SC. Drug-drug interactions with OTC medicines: mind the unprescribed [published online ahead of print August 27, 2021]. Ther Drug Monit. doi:10.1097/FTD.0000000000000924