Pharmacovigilance is the science and activities relating to the detection, assessment, understanding and prevention of adverse effects or any other drug related problems. One of the ways to carry out the pharmacovigilance activities are through investigator initiated post authorization safety studies/post marketing surveillance studies. These are scientifically rigorous studies of a product or a class that is approved for registration in a particular country, designed to produce reliable information about the drug safety. It is a well-established fact that premarketing clinical trials do not have the statistical power to detect rare ADRs nor do they have significant follow-up to identify delayed ADRs or effects from long-term exposure. In view of this, pharmacovigilance plays a prominent role in establishing the safety profile of marketed drugs.