Pharmacovigilance

Definitions & scope

• Pharmacovigilance (WHO 2002) — the science and activities relating to the detection, assessment, understanding and prevention of adverse effects or any other drug-related problem; ensures safe, rational use across the entire drug life-cycle — a marketed drug's safety profile is not fixed at approval and must be reassessed continuously.
• Scope beyond ADRs — extends to medication errors, drug-quality problems, off-label use, counterfeit/substandard products, drug interactions, abuse/misuse and lack of efficacy.
• ADR (WHO) — any response to a drug that is noxious and unintended occurring at doses normally used for prophylaxis, diagnosis or therapy; excludes overdose, accidental exposure and trivial side effects. Edwards & Aronson (2000): a harmful reaction that predicts hazard from future use and warrants prevention, treatment or dose alteration/withdrawal.
• ADE vs ADR — an adverse drug event is any untoward occurrence during treatment without a necessarily causal link — the broader umbrella; an ADR is the subset with established causality.
• Allied terms — side effect (predictable, dose-related); idiosyncrasy (genetically determined qualitatively abnormal reactivity, e.g. primaquine haemolysis in G6PD deficiency); intolerance (toxic effect at therapeutic dose); iatrogenic disease (physician-induced); pharmacoepidemiology supplies PV its quantitative cohort/case-control tools.