Off-Label Use & Medication Errors

Definitions & overview

• Off-label use — prescribing a marketed drug for an indication, population, dose or route not listed in the regulator-approved labeling (package insert / SmPC). Legal for a licensed prescriber, but the use is not backed by the regulator's efficacy/safety review for that purpose.
• vs unlicensed use — off-label = the drug is approved but the specific use is not; unlicensed = the drug is not approved at all (extemporaneous or imported formulation).
• Medication error (NCC MERP) — any preventable event that may cause or lead to inappropriate medication use or patient harm while the medicine is in the control of the professional, patient or consumer. The qualifier preventable separates an error (a defect in the medication-use system) from an idiosyncratic ADR (a defect in the patient's biology).
• ADE vs ADR — an adverse drug event is any untoward occurrence during treatment without a necessarily causal link (the umbrella term — record first, assess causality later); an ADR is a noxious response at normal doses requiring treatment/dose change/caution (WHO; excludes overdose and trivial side effects).
• Why taught together — both off-label use and medication errors are properties of how the drug is used, not of the drug itself (G&G Fig. 8-1), and both are leading, largely preventable causes of drug-induced (iatrogenic) disease — premarketing trials studied a narrow use in a narrow population, yet the drug is then given off-label through an error-prone chain to millions never studied.