Table 1.

Pharmacokinetic changes in the elderly

Physiological process	Situation in the elderly	Changes	Effect
Absorption	Decreased	Atrophy of the intestinal mucosa Decreases in gastrointestinal motility	Reduced absorption of protein, vitamins and drugs
		Decreased splanchnic blood flow
		Decreased secretion of digestive enzymes
Metabolism	Decreased	Reduced liver size	Reduced protein synthesis
		Reduced hepatic blood flow	Reduced activation/deactivation of drugs and carcinogens
		Reduced activity of cytochrome p450-dependant reactions
Drug distribution	Decreased	Reduced total body water	Reduced Vd of water-soluble drugs
		Reduced concentration of plasma albumin	Increased Vd of liposoluble drugs
		Reduced red blood cell concentration
Excretion	Decreased	Reduced glomerular filtration rate	Reduced elimination of drugs and of their active metabolites
		Reduced tubular function

Vd: Volume of distribution.