Adverse drug reactions account for a significant proportion of all U.S. hospitalizations; estimates range as high as 18 percent of hospital admissions. The Phase I objective is creation of a microcomputer-based prototype for physicians and pharmacists that would use integrated-circuit cards ("smart cards") to warn practitioners of inappropriate drug therapy. Physicians will write a patient's prescription on a smart card; the patient will present the card to a pharmacist. An interactive program will analyze new prescriptions and issue an on-screen notice of any significant risks based on the patient's clinical history and current drug use; however, the system will not impede the physician from writing, nor the pharmacist from filling, a prescription. Because the elderly are more likely than other age groups to be treated for multiple symptoms by different specialists, this system should improve patient management, provide a more thorough therapeutic record and reduce Medicare expenditures for hospitalization. The team for this project will bring together substantial expertise in the development of pharmacy databases and smart card applications. The ultimate objective is a commercial system for carrying patient data that will prevent inappropriate drug therapy and facilitate drug-bill processing for third-party insurance plans.