[Multiple drug addiction].

The "polydrug use" well known at the USA, has sprayed in France and Europe during the last ten years. Harms of polydrug use were pointed out by some specialized centers. The aim of this work is to emphasize the dangers of the abuse of some drug associations. Animal pharmacology, clinical observations and epidemiology are the main research method involved animal in the study of "polydrug use". These methods are often difficult to perform in elderly persons and in pregnant women. It is not easy to extrapolate from animals to man. The pharmacokinetics of drugs often differs from a species to another. Animal models are nevertheless useful for studies dealing with drug interactions, especially with enzyme metabolism. Clinical studies will be dependent on the ethical questions. Some examples are mentioned. Alcohol use develops in many drug addicts, particularly in those on methadone maintenance. The association of cocaine and other amphetamine-type stimulants with morphinics or cannabis is very dangerous. Other associations are quite frequent including various hypnotics or cough suppressants (even nomorphinic). "Polydrug use" generally increase mortality in drug addicts. The medical profession is not well informed on this subject. Further research must be led on the harmful effects of drug associations and on the reasons leading drug addicts to multiplicate drug associations in an almost epidemic way.