Page 1 of 1

Physicians correctly identify fewer than half of drug pairs with potentially dangerous interactions

Research Activities, May 2009, No. 345

An average of 2.3 medications are prescribed during each physician office visit. One risk associated with the use of multiple medications is the possibility of potentially dangerous drug-drug interactions (DDIs).

DDIs can lead to an emergency department visit, admission to the hospital, and sometimes death. Yet, 950 clinicians in a recent survey correctly identified only 43 percent of drug pairs with potential DDIs. This suggests that prescribers' knowledge of potentially clinically significant DDIs is generally poor, conclude the researchers at the University of Arizona and the Arizona Center for Education and Research on Therapeutics (CERT). They mailed a questionnaire to a national sample of 12,500 prescribers who were selected on the basis of a past history of prescribing drugs associated with known potential for DDI. Recipients were asked to classify 14 drug pairs as "contraindicated," "may be used together but with monitoring," or "no interaction." They could also state that they were "not sure."

The 950 responding prescribers classified 42.7 percent of all drug combinations correctly. Correct classification of specific drug pairs ranged from 18.2 percent for warfarin and cimetidine to 81.2 percent for acetaminophen with codeine and amoxicillin. The number of drug pairs correctly classified by individual prescribers ranged from 0 to 13. For half of the drug pairs, over one-third of the respondents answered that they were "not sure," and two of these drug pairs were contraindicated. One-fourth of the prescribers used personal digital assistants (PDAs) to learn more about a potential DDI and a similar number used printed material. However, about two-thirds of prescribers reported their information on patients' potential exposure to DDIs usually came from pharmacists, underscoring the important role of pharmacists in reducing potential DDIs.

The study was supported by the Agency for Healthcare Research and Quality (HS10385) to the Arizona University CERT. For more information on the CERTs program, please visit

More details are in "Prescribers' knowledge of and sources of information for potential drug-drug interactions," by Yu Ko, Ph.D., Daniel C. Malone, Ph.D., R.Ph., Grant H. Skrepnek, Ph.D., R.Ph., and others, in Drug Safety 31(6), pp. 525-536, 2008.

Current as of May 2009
Internet Citation: Physicians correctly identify fewer than half of drug pairs with potentially dangerous interactions: Research Activities, May 2009, No. 345. May 2009. Agency for Healthcare Research and Quality, Rockville, MD.