Principal alterations to drug kinetics and dynamics in the elderly.

People over the age of 64 constitute 15% of the population in the UK, yet they consume approximately 30% of all National Health Service drug prescriptions, and adverse drug reactions account for 10.4% of all admissions to geriatric medical assessment wards. Many published studies concerning the pharmacology of old age are seriously flawed. Problems include failure to measure the drug bio-availability and the selection of subjects with overt or sub-clinical disease. It is difficult to make general rules about the effect of ageing on drug kinetics and dynamics. Each drug has to be tested separately.