[Drug therapy in the elderly]

The elderly are known to be more susceptible to adverse drug reactions. Age differences in pharmacokinetics (i.e., absorption, distribution, metabolism, and elimination) may contribute to an increased susceptibility of the elderly to both the therapeutic and toxic effects of some drugs. For many drugs studied, such pharmacokinetic differences are generally consistent with age differences in body composition, renal function, and protein binding. Ageing is associated with a decrease in lean body mass and total body water, and a decline in glomerular and tubular function in the kidney, and diminished cardiac output and liver blood flow. In addition to considering the epidemiology of adverse drug reactions and the altered physiology and pharmacokinetics in the elderly, this review attempts to provide an overview of what is known about the relationship between advanced age and the pharmacokinetics of some drugs mainly eliminated via the kidney. Thus, several methods are presented to permit rational dosage regimen modifications for elderly patients with diminished renal function. Based on a review of the accumulated literature related to clinical geriatric pharmacology, it is concluded that dosage regimen adjustments based on therapeutic drug monitoring are essential to make drug therapy in the elderly safer and more effective.