Detecting drug interactions: a review of the literature.

This article provides a historic overview of drug interaction screening and reviews 19 studies that have sought to measure the frequency of drug interactions. Differences in study designs, methodologies, and definitions contribute to considerable variation in the reported incidence rates, which ranged from 2.2 to 70.3 percent for all potential drug interactions. The percentage of patients actually experiencing symptoms that could be attributed to a drug interaction, however, ranged from 0 to 11.1 percent. The relative importance of drug interactions as a clinical problem remains unclear. Screening programs that do more than simply identify large numbers of patients who receive potentially interacting drug combinations without indicating which subpopulations of these individuals are likely to be harmed by the drugs have not yet been developed.