[Ethics problems in phase IV of drug studies]

Phase IV clinical studies include all investigations carried out after the approval of drugs. The objective of these studies is well defined: to gain additional knowledge on efficacy and safety of drugs. There are uncertainties however with regard to which kind of study design is appropriate to provide scientifically valid contributions. In the present article we will clarify why an experimental design (e.g. randomized clinical trial) is ordinarily required, on the basis of scientific and ethical concerns, to answer questions concerning efficacy even after drug commercialization. Viceversa, non experimental designs (from case series analysis to cohort and case control studies) are indicated to investigate drug effects in current practice if the objective is to evaluate safety.