More than a half-million preventable drug-related injuries occur among Medicare outpatients each year. And a quarter of medication errors are attributed to poor drug packaging and labeling.

To combat this, the Institute of Medicine recommends generally applicable safety strategies such as reducing polypharmacy and spreading adoption of electronic prescribing, medication reconciliation and clinical decision support. Yet new research suggests that interventions are needed to target the specific medicines that most commonly harm patients.

Adverse drug events send at least 265,000 seniors to U.S. emergency departments every year and hospitalize nearly 100,000 patients 65 and older, according to a Nov. 24, 2011, study in The New England Journal of Medicine. What is striking, experts say, is the study’s finding that four kinds of medications — warfarin, insulins, oral antiplatelet agents and oral hypoglycemic agents — together account for seven in 10 emergency hospitalizations among seniors.

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