[Side effects of drugs in the elderly. A review of various possible causes].

About 40% of the intoxications after drug administration occur in the elderly. The occurrence of these intoxications must be attributed to: 1. an increased distribution of the lipophilic drugs over the body by which they stay longer in the body; 2. a decreased distribution of hydrophilic drugs over the body by which the drug concentration in the blood becomes higher; 3. a decreased metabolism of lipophilic drugs; 4. a decreased urinary excretion of hydrophilic drugs; 5. an increased sensitivity of the tissues, by which an increased effect occurs; 6. interactions between simultaneously administered drugs, by which their effect is increased; 7. a wrong compliance, by which in some cases too high concentrations of the drug occur in the blood. On the basis of the reviewed literature it can be stated that research should be specifically devoted to the effect of age on the metabolizing system of the liver, pharmacodynamics and drug interactions.