[Drug interactions and the elderly].

Elderly people are particularly at risk for drug interactions, for several reasons. They are the part of the population who consume the most drugs: over 75 years the mean number of drugs on a prescription is 5.6. As they suffer from various associated diseases, they see several medical specialists, each of them adding a new prescription to the others. Self-prescriptions complicate the problem because they are rarely mentioned. Changes in pharmacokinetics in the elderly tend to increase blood concentrations of drugs. Elderly people suffer from altered homeostatic mechanisms to compensate for adverse drug effects. As a whole, such individuals are more exposed to the side effects of drugs. The drugs most often involved in these interactions are diuretics, non-steroidal anti-inflammatory drugs, benzodiazepines, antiarrhythmics, cardiac glycosides, antihypertensive drugs, oral antidiabetics and antalgics. The clinical accidents most often occurring with these drug interactions are: malaise, orthostatic hypotension, loss of conciousness, amnesia, confusion, renal insufficiency, digestive problems. Since elderly people are less likely to recover easily, this problem of drug interaction should be looked for systematically.