Pharmacy Research Shows Prescribers Identify Fewer Than Half of Dangerous Drug Combinations

Medication prescribers correctly identified fewer than half of drug pairs with potentially dangerous interactions, according to research led by the UA College of Pharmacy.

Medication prescribers correctly identified fewer than half of drug pairs with potentially dangerous drug-drug interactions, according to research led by The University of Arizona College of Pharmacy.

These findings raise concern because of the high number of drugs Americans take – an average of 2.3 medications are prescribed during each physician office visit. A synopsis of the research was published in a recent issue of Research Activities, a digest of research findings intended to contribute to the national policymaking process.

Led by Daniel Malone, professor at the UA College of Pharmacy, researchers mailed a questionnaire to 12,500 U.S. prescribers who were selected based on a history of prescribing drugs associated with known potential for drug-drug interaction. Prescribers primarily were physicians, physicians' assistants and nurse practitioners.

Recipients were asked to classify 14 drug pairs as "contraindicated," "may be used together but with monitoring" or "no interaction." Respondents also could state that they were "not sure."

For the drug pairs, one commonly prescribed medication was matched with another commonly prescribed medication. The 950 respondents classified 42.7 percent of all drug combinations correctly.

Of the 14 drug pairs presented, four of them were contraindicated, meaning they should not be used together. A majority of prescribers correctly identified only one of the four pairs as contraindicated. Moreover, for half of the 14 drug pairs, more than one-third of the respondents answered that they were "not sure," and two of these drug pairs were contraindicated.

"The study found a very low rate of recognition of these particular interactions," Malone said, "and some of these interactions are very common."

Use of several of the contraindicated drug pairs could be dangerous. For example, taking sildenafil (Viagra) and nitrates such as isosorbide mononitrate can be life-threatening.

The research indicates that health professional programs are not doing enough to teach students about potential drug-drug interactions, Malone said. Consequently, patients should be sure to tell their pharmacist of all the medications they are taking.