Chapter 2: Adverse Drug Effects and Chemical Toxicity

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2.1:

Pharmacovigilance

JoVE Core
Pharmacology

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JoVE Core Pharmacology

Pharmacovigilance

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2.2: Drug Dependence

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Several unrecognized adverse drug reactions become known during post-marketing surveillance—after a drug has been used by a broader set of patients over considerable periods. This monitoring, known as pharmacovigilance, involves detecting, assessing, and preventing drug-related adverse effects. Data collected using the spontaneous reporting system is on a voluntary basis or a legal requirement to report any suspected adverse effect. Signals are detected from the reported data to find a causal relationship between the adverse event and the drug, which was previously unknown. To further evaluate the suspected ADR, a causality assessment based on temporal relationship, pharmacological plausibility, dechallenge, and rechallenge is carried out. The assessment grades the causality as definite, probable, possible, or unlikely. Drugs with adverse effects are flagged by different regulatory bodies. The information is disseminated through drug alerts, medical journals, updating the labels with warnings or precautions, or even withdrawing the drug from the market.

2.1:

Pharmacovigilance

Post-marketing surveillance is a critical component of pharmaceutical regulation, often uncovering unanticipated adverse drug reactions (ADRs) once a drug is widely used over an extended period.

This process, termed pharmacovigilance, aims to detect, evaluate, and minimize harmful effects related to medication use. The data collection for pharmacovigilance depends on spontaneous reporting systems, where healthcare professionals or patients voluntarily report suspected ADRs.

In some cases, there might be a legal obligation to report potential adverse effects. These reported data are then examined for 'signals,' which are potential causal links between the drug and the reported adverse event that were not identified earlier. For validation of these signals, a causality assessment is performed. It involves examining various elements, such as the temporal relationship between drug administration and the ADR, the pharmacological plausibility of the reaction, and the outcomes of dechallenge and rechallenge tests.

Post-evaluation, the causality is classified as definite, probable, possible, or unlikely. Regulatory bodies flag drugs exhibiting adverse effects. These findings are disseminated through channels like drug alerts, medical journals, and updates to drug labels with suitable warnings or precautions. In severe cases, the drug may be removed from the market.