Pharmacoepidemiology, Adverse and Beneficial Effects

Pharmacoepidemiology has been defined as “the study of the distribution and determinants of drugrelated events in populations and the application of this study to efficacious drug treatment” [26]. Similar definitions have been given by several authors [37, 53]. The term “drug” in the definition is generally understood to include biologics, such as vaccines, and the populations are understood to be human. The emphasis is on studies of the safety and effectiveness of drugs used for medical purposes. Both randomized (see Clinical Trials, Overview) and nonrandomized (observational) designs are used, with the latter being more common, especially for the study of adverse effects. Pharmacoepidemiology may be regarded as a subdiscipline of both clinical epidemiology and clinical pharmacology [53]. However, clinical pharmacologists typically use small, carefully controlled studies to examine drug pharmacokinetics (absorption, distribution, metabolism, and excretion) and pharmacodynamics (the relationship between the drug level and drug effects), while pharmacoepidemiologists typically examine drug effects in larger populations under conditions more representative of clinical practice. Pharmacoepidemiology is an essential component of risk management of pharmaceutical products. Risk Management “encompasses processes for identifying and assessing the risks of specific health hazards, implementing activities to eliminate or minimize those risks, communicating risk information, and monitoring and evaluating the results of the interventions and communications” [56]. Current US federal regulations require evidence of both safety and effectiveness of drugs prior to approval for marketing (see Drug Approval and Regulation). However, such evidence is limited by the extent, duration, and patient characteristics of preapproval clinical trials. In addition, unexpected potentially beneficial effects are sometimes found after marketed use and questions may arise about