Hazards of Drug Therapy : On the Management of Adverse Drug Reactions: From Signal Detection and Evaluation to Risk Minimization

Abstract: Spontaneous reporting systems (SRSs) for adverse drug reactions (ADRs) have been developed as a result of the thalidomide disaster, whereby thousands of children world-wide were born with birth defects. The Swedish Adverse Drug Reactions Advisory Committee was established in 1965. Since 1975, reporting has been compulsory for all suspected serious or new ADRs. International collaboration started in 1968 with countries contributing their ADR reports to an international database set up by the World Health Organization. ADRs represent the negative side of the benefit-to-risk balance that in theory needs to be counteracted by perceived or established positive drug effects. All drugs are subject to preclinical and clinical testing prior to marketing authorization. However, these studies are insufficient to detect rare ADRs, ADRs that occur after long-term administration or with latency, ADRs that occur in special patient groups such as children, the elderly, patients with renal or hepatic insufficiency or patients on concomitant drug treatment, and ADRs that represent a modest increase in the risk of diseases (including mortality) that are prevalent in the study population. Postmarketing surveillance of drugs is therefore essential, and regulatory action may be needed on the basis of new ADR information. SRSs are important sources of ADR information as exemplified here by the evaluation of peripheral sensory disturbances with fluoroquinolones, hyponatremia with antidepressants, blood dyscrasias with dipyrone, glucose intolerance with atypical antipsychotics, pulmonary embolism with combined oral contraceptives and extrapyramidal symptoms with selective serotonin reuptake inhibitors. SRSs can be used to study clinical manifestations of ADRs (that can give insights into potential ADR mechanisms), risk factors for the ADR or for specific outcomes of the ADR, and ADR reporting incidences when combined with sales data. Signals from SRSs may need to be studied further e.g., by use of large-scale epidemiologic studies based on record linkage between drug prescription databases and health databases. Owing to the rapid availability of information, however, SRSs are likely to remain of major importance for the post-marketing surveillance of drugs.