[Changes in pharmacokinetics in elderly patients].

Age-related physiological and morphological changes may influence drug disposition. Age-related decreases in gastric acid secretion, gastrointestinal motility and blood flow may alter drug absorption, but no significant age-related change in drug absorption is observed. With aging, body fat increases and total body water decreases. Therefore, water-soluble(hydrophilic) drugs have a higher peak plasma levels in the elderly. Inversely, lipid-soluble (lipophilic) drugs have an increased volume of distribution in the elderly. Age-dependent decrease in the serum albumin concentration influences drug protein binding potency. Age-related reduction in liver size, hepatic blood flow and hepatic drug-metabolizing enzyme activity decreases the hepatic drug clearance. The decreases in renal blood flow, glomerular filtration rate (GFR) and tubular secretion have a considerable impact on the renal clearance of drugs.