Development of new drugs is composed of the following stages:

• screening for new active substances based upon pharmacological studies
• toxicity studies on animals
• clinical trials:

Phase I - Studies are carried out on healthy volunteers to determine the maximal dose tolerated.

Phase II - Studies are carried out on patients to assess whether the substance is sufficiently active to justify further studies.

Phase III - Studies are carried out to compare new treatment with a reference treatment or a placebo.

Phase IV - Studies are carried out to assess the long term effects on the general population, or pharmacovigilance studies.

Clinical research refers to all the clinical studies performed in man. Phases I to III are necessary to test the quality, safety and efficacy of the treatment and to obtain marketing authorization granted by the French Drug Evaluation Agency.