[Pharmacoepidemiology: definition, methods and applications].

Clinical evaluation of drugs before approval is based on the experimental design of clinical trial with randomization of drug exposure. Unfortunately, conclusions of clinical trials are necessarily limited to patients enrolled in the trial. It is therefore necessary to compare these experimental data from clinical trials with the real use of drugs in clinical practice. Pharmacoepidemiology is defined as the study in real conditions and on large populations, of use, effectiveness and risk of drugs. The methods and fields of application of pharmacoepidemiology are described. They allow to characterize conditions of use, misuse, clinical effectiveness, adverse drug reactions and risks of drugs. The development of pharmacoepidemiology should allow optimization of "rational use" of drugs.