Pharmacoepidemiology is the study of the use and the effects of drugs in large numbers of people. The term- “pharmacoepidemiology”- obviously contains two components: “pharmaco” and “epidemiology”(1). The main scope of pharmacoepidemiology is to explore the therapeutic effects, indications, and adverse drug reac- tions (ADR) using the techniques of epidemiology. The origin of pharmacoepidemiology, however, was due to the limitations of clinical trials.