Disposition of drugs in the elderly.

Adverse drug reactions not only occur more frequently but are also of a more severe nature in the elderly. For warfarin and many of the psychoactive drugs, this is due mainly to an increased pharmacodynamic sensitivity to the actions of these drugs. For a number of other drugs, old age is associated with changes in their distribution and eventual elimination from the body. This increases the risk of a relative overdose during routine use of the drug. Such risks can be minimised by the judicious adjustment of the dosages of these drugs.