How the Medicines Authority monitors the safety of medicines 

Before a medicine is placed on the market, information on the safety and effectiveness of medicines is mostly known from research in animals and from its use in humans through clinical trials. However, clinical trials are not always reflective of the actual market situation, due to limitations which include; 

• a low number of subjects participating in the trial
• exclusion of some age groups
• other diseases not being present in the subjects
• other medicines not being taken by the subjects
• the clinical trial not being long enough to reveal any long term side-effects.  

Despite there being extensive research before a medicine is given an authorisation some Side Effects, also known as Adverse Drug Reactions (ADRs) may not be seen until a very large number of people have received the medicine. Therefore, it is recognized that once medicines are placed on the market they need to be continuously monitored throughout their time on the market. This process of surveillance is known as Pharmacovigilance.