[Clinical pharmacology and aging].

Clinicians must be aware that aging can lead to changes in the pharmacokinetics and pharmacodynamics of many drugs. Drug distribution may be modified with aging secondarily to the decrease of serum albumin and to modifications of body composition (increase in the proportion of fat mass and decrease of lean mass). Hepatic metabolism of several drugs is reduced with age, especially drugs which depend of hepatic blood flow or P450 cytochroms. The incidence of renal failure increase largely with age. Glomerular filtration rate should be systematically estimated in older patients and, when needed, the doses of those drugs having significant renal elimination should be adjusted. In older patients, changes in the response to drugs can also develop, concerning specially the central nervous system (increased sensibility to any neurological effect of drugs), the cardiovascular system and the renal management of water and electrolytes. In many cases, the pharmacological changes associated to age are mild and requires no dose adjustment. However, many drugs should be adapted depending on the individual situation of each patient, particularly his renal function and nutritional state. Finally, some drugs should be avoided in older patients because of a bad effectiveness/tolerance ratio compared to alternatives.