[Pharmacokinetics and the aged person].
Visceral insufficiencies appeared or might be more important with age, thus it is not surprising to note pharmacokinetic alterations in elderly subjects. There are several age related changes in gastrointestinal function that might alter absorption of drugs. Gastric acid secretion and motility both decline with age. Intestinal surface and blood flow also diminished. But the effect of these changes is far eclipsed by other factors. The plasma-binding proteins diminish. The intracorporeal distribution of drugs is modified in elderly subjects. Total body weight and especially lean body mass is reduced: thus higher plasma levels of drug result. Hepatic clearance is in relation to liver mass and hepatic blood flow, both of which diminish with age. Hepatic enzymatic function, particularly oxidative process, is also decreased. The most important modification is a reduced excretion of drugs. Renal blood flow, glomerular filtration rate are decreased and these alterations may induce an accumulation of drugs or metabolites. Thus, it is necessary to be cautious when we prescribe drugs to elderly patients. We recommended to give small dosage and to increase dosage progressively. It is also necessary to pay attention to clinical or biological signs of intolerance in these subjects.
Fillastre
J P
JP
Service de Néphrologie, CHU de Rouen.
Moulin
B
B
Dhib
M
M
D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D005744:Gastric Acid / Q000378:metabolism; D005753:Gastric Mucosa / Q000502:physiology; D006801:Humans; D007422:Intestines / Q000502:physiology; D007668:Kidney / Q000502:physiology; D008099:Liver / Q000502:physiology; D010599:Pharmacokinetics
Pharmacocinétique et sujet âgé.