Introduction to Drug Safety and Pharmacovigilance

This chapter will introduce the main terms and concepts related to drug safety. This includes definitions, epidemiology, diagnosis, and classification of adverse drug reactions (ADRs) as well as the shift to a more holistic view of drug safety in relation to medication errors, issues in clinical practice, and regulatory approaches. The development of modern pharmacovigilance and drug safety practices can be attributed to a series of drug safety events that took place throughout the twentieth century. Even with high-quality randomized controlled trials, the safety of new medicines is not guaranteed due to limitations of the clinical trials, such as trial size, exclusion of subjects at risk of developing ADRs, short trial durations, and the nature of potential ADRs. Clinical trials are unlikely to detect infrequent ADRs or those that are delayed. Once marketed, large numbers of individuals can be exposed to the drug and detection of new ADRs is possible. Spontaneous reporting of ADRs by health-care professionals and patients is one of the primary methods of detecting new safety signals, and post-marketing observational studies using real-world data are used to investigate potential signals. For methodological reasons, several terms related to ADRs, as well as dictionaries of ADRs, have been developed, which are essential for the quantitative examination of drug safety issues. Pharmacovigilance is a collaborative venture including health-care professionals, patients, regulators, and pharmaceutical companies to ensure that the chances of finding new safety issues are maximized. Even following successful detection of an ADR, the complex communication and ethical issues present challenges. In clinical practice, the burden of harms generally comes from the most frequently used drugs, and good patient management is enhanced by understanding of the principles and methods in pharmacovigilance and the safe use of medicines. At the local level, managing polypharmacy in an aging population will become increasingly challenging. The future of pharmacovigilance will see major developments in pharmacoinformatics, artificial intelligence, and pharmacogenomics. Continued educational efforts at both the undergraduate and postgraduate levels are required to enhance the effective practice of drug safety and pharmacovigilance.