Pharmacokinetics in the Elderly

Pharmacokinetics in the Elderly
Definition: Pharmacokinetics is the way the body absorbs, distributes, metabolizes, and excretes medication. Age-related physiological changes affect body systems, alter pharmacokinetics, and increase or alter a drug’s effect.
	Physiological Change	Effect on Pharmacokinetics
Absorption	■ Decreased intestinal motility ■ Diminished blood flow to the gut
Distribution	■ Decreased fluid volume	■ Increased serum concentration of water-soluble drugs
	■ Increased body fat percentage	■ Increased half-life of fatsoluble drugs
	■ Decreased plasma proteins	■ Increased amount of active drug
	■ Decreased lean body mass	■ Increased drug concentration
Metabolism	■ Decreased blood flow to liver	■ Decreased rate of drug clearance by the liver
	■ Decreased liver function	■ Increased accumulation of some drugs
Excretionº	■ Decreased kidney function ■ Decreased creatinine clearance	■ Increased accumulation of drugs that are normally excreted by the kidneys