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May 4, 2021

Medical Terms & Explanations 101 x Adverse Drug Reactions

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According to the European Medicines Agency (EMA), adverse drug reactions (ADRs) are “adverse and unintended reactions to a drug.”[1] These side effects can be caused by any pharmacologically active drug, even when used as intended.

Side effects caused by (intentional or unintentional) excessive use of drugs, on the other hand, are referred to as toxicity.

When prescribing drugs by healthcare professionals, a risk/benefit assessment is necessary, as all drugs can theoretically produce UAs.[2] For this reason, patients must be aware of the risks and be informed accordingly before use.

How can adverse drug reactions occur?

UAWs often result in low selectivity of the active ingredients. Selectivity generally describes how many different structures or tissues an active ingredient binds to.[3] The higher the selectivity, the fewer structures are bound that can potentially cause UAWs.

Another resulting reason is the different patient groups. The studies that drugs must go through before they are approved for the market often have high inclusion criteria, which exclude relevant target groups. In very old or pregnant people, for example, these drugs can then cause UAWs in the real world.

Where can I find the relevant information?

Corresponding information can be found in the package leaflet, the medicinal product description or web platforms, such as EudraVigilance or ImpactMonitor. This information on adverse side effects comes from the above studies, from application-related data collections or from spontaneous reports submitted by Real-world evidence can be attributed.

Importance of reporting adverse drug reactions

Doctors, pharmacists, pharmaceutical manufacturers and patients are therefore in high demand to help uncover adverse drug effects.[4] This increases patient and drug safety in the long term. Reporting ADRs is absolutely necessary, especially for newer drugs that only have conditional market approvals, for example. By the way, such reports can be recorded easily and securely via the ImpactMonitor.


[1] European Medicines Agency. Adverse drug reaction. Last accessed: 15.03.2021

[2] Smith Marsh E. Daphne. 2018. PharmD. BC-ADM. CDE. College of Pharmacy. University of Illinois at Chicago.ünschte-arzneimittelwirkungen/das-nutzen-risiko-verhältnis-von-medikamenten Last accessed: 15.03.2021

[3]Urban JD et al. Functional selectivity and classical concepts of quantitative pharmacology. J Pharmacol Exp Ther. 2007. 320 (1) p. 1-13.

[4] Barry, A.R., Koshman, S.L., & Pearson, G.J. (2014). Adverse drug reactions: The importance of maintaining pharmacovigilance. Canadian pharmacists journal: CPJ = Canadian Pharmacists Review: RPC, 147 (4), 233—238. Misunderstanding randomized controlled trials. Vol 210. p. 2-21.

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