Post-marketing surveillance is essential in order to protect patients against avoidable risks from medication. Complete assessment of a drug cannot, for practical reasons, be made before marketing. There are several methods which can be used in post-marketing surveillance. Spontaneous reporting on adverse drug reactions is a quick method, but underreporting is a problem. Intensive monitoring gives high quality data but is expensive. Health registers can be used to trace cases for case-control studies but diagnoses are sometimes incorrect. Prospective studies is an informative way to obtain results but they take time. Data on drug utilization are also valuable because they give an estimate of the size of the population using a particular drug. They also reveal whether warnings about adverse drug reactions have had any effect on the prescribing pattern.
PIP: Given the infeasibility of complete clinical assessment of a drug before it is made available for general use, postmarketing surveillance assumes an essential role in detecting rare adverse effects. A variety of methods are available for postmarketing surveillance. The first reports on adverse drug effects generally come from individual physicians who report suspected problems to medical journals, a drug reporting center, or to the drug industry. Such spontaneous reporting is a quick, inexpensive method; however, underreporting and nonrepresentativeness are disadvantages. Intensive monitoring through systems that monitor both drug intake and drug effects gives high-quality data but is expensive. Health registers can be used to trace cases for case-control studies, although the quality of the discharge diagnoses is often questionable. Prospective investigations that compare cohorts using a drug with nonusers provide reliable data on the incidence of drug effects and can study several adverse reactions simultaneously. The drawbacks are the costs and the late appearance of data. Finally, data on drug utilization are valuable because they give an estimate of the size of the population using a given drug and indicate whether warnings about adverse drug reactions have an effect on prescribing patterns.