Postmarketing Surveillance

Abstract

The postmarketing monitoring and evaluation of the safety and effectiveness of all medicines is essential. The patterns of use, effectiveness and safety of a drug in general use may be substantially different to that in clinical trials due to differences in prescribing and patient groups; differences include the limited number of patients in studies, restrictions in patient populations (e.g. pregnancy and nursing mothers, children, the elderly and those predisposed to develop adverse events are frequently excluded), and the limited duration of drug use or period of evaluation in clinical trials. In addition, knowledge about effectiveness and safety in off-label use and interactions with concomitantly used drugs remains unknown. It is important to recognise that clinical trials and postmarketing surveillance address different issues. Postmarketing surveillance data provide new information that was unavailable in premarketing studies. Much larger observational studies can be done, at a lesser cost, to evaluate a drug in a customary use situation. Highest priority in a postmarketing surveillance system should be given to new chemical entities, populations in which drug effects are not well documented, certain important medical events (e.g. birth and death) and their relationship to drug use and pattern of prescription. Surveillance per se, or its results, will not and cannot be used to change the biological properties or effects of a drug, but can be used to minimise the harmful consequences and maximise the optimal use of a drug. LEADING ARTICLE