Polypharmacy in the Elderly: Drug reactions and interaction in the aged.

The elderly tolerate smaller doses of most drugs, largely because changes in body fat content, water content, and muscle mass often lead to higher blood levels than in a young person of the same weight. Moreover, diminished renal blood flow and creatinine clearance decrease excretion of agents cleared by the kidney. This leads to an increased number of drug reactions and interactions and consequent hospital admissions.