Pharmacovigilance

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.