Principles of drug therapy in geriatric patients.

The elderly comprise 12 percent of the U.S. population but consume 33 percent of all prescription drugs. The incidence of adverse drug reactions is significantly higher in persons over age 65 than in younger population groups. The increased risk of adverse drug effects is related to decreased organ reserve capacity, to altered pharmacokinetics and pharmacodynamics, and to polypharmacy with associated drug-drug and drug-disease interactions. An organized therapeutic plan and critical evaluation of the list of drugs an elderly patient is taking will help in establishing a safe and effective drug regimen.