What does “post marketing surveillance” – also known as Phase 4 trials – mean?


Post marketing surveillance concerns the last and 4th Phase of a clinical trial.After a medicine has been launched, Health Authorities are often asking companies to provide additional data, collected from the actual use of the medicine in thousands of patients. Phase 4 studies are designed to provide broader experience in evaluating the safety and effectiveness of the new medicine in larger numbers of patients, subgroups of patients, and to compare and/or combine it with other available treatments. These studies are designed to evaluate the long term effects of the drug. Less common side effects may be detected at this stage. Despite the vigilant tests carried out during clinical trials in the other three Phases, active post marketing surveillance of drug side effects is essential. Not all potential side effects of a medicine can be anticipated based on only several hundred to several thousand patients. Therefore, clinical trial sponsoring enterprises maintain a system of risk assessment programs to identify side effects that did not appear during the other trials. Information on adverse events that have been brought to the attention of the marketing authorisation holder are collated. This is also called "Pharmacovigilance" (i.e. the safety of medicines).