Age-related changes in drug handling in man.

Persons older than 65 years constitute 10% of the U.S. population but require approximately one-third of its health care service. A significant proportion of their disease states is related to adverse reactions to prescribed drugs. The origins of this disturbingly high incidence of untoward consequences from drug therapy are multiple and complex. They include: (1) alterations in expected patterns of drug handling associated with physiologic changes of the aging process itself, (2) alterations in responsiveness to specific types of drugs and (3) frequent occurrence of chronic and acute diseases. The data documenting pharmacokinetic changes in aging subjects are rudimentary, and the physician is commonly aware only of pharmacokinetic profiles derived from studies in healthy, young subjects. Without a firm basis on which to rest pharmacologic therapy, the clinical approach to drug treatment in the elderly patient must be cautious and conservative.