ADVERSE DRUG REACTION:

The definition of an ADR is often confused with that of an Adverse Drug Event (ADE). The World Health Organization (WHO) defines an ADE as “any untoward medical occurrence that may present during treatment with a pharmaceutical product but which does not necessarily have a causal relationship with this treatment.

The WHO defines an ADR as “a response to a drug which is noxious and unintended and which occurs at doses normally used in man for prophylaxis, diagnosis, or therapy of disease or for the modification of physiologic function.”

An ADR is a type of ADE whose cause can be directly attributed to a drug and its physiologic properties.

ADR X ADE:

A main distinction between ADRS and ADEs is that ADRS occur despite appropriate prescribing and dosing, whereas ADEs may also be associated with inappropriate/irrational use of the drug or other confounders that occur during drug therapy but are not necessarily caused by the pharmacology of the drug itself. A causal relationship is suspected for an ADR but is not required for an ADE.

ADES may also be caused by medication errors, which the National Coordinating Council for Medication Error Reporting and Prevention (NCC MERP) defines as “any preventable event that may cause or lead to inappropriate medication use or patient harm while the medication is in the control of the health care any delivering professional, patient, or consumer. It is also errors in the process of ordering or a medication, regardless of whether an injury occurred or the potential for injury was present or Inappropriate use of a drug that may or may not result in harm.

Published studies of ADRS, ADES, and Medication Errors often use these terms interchangeably, leading to inconsistency in the reported prevalence of each. Definitions are often subject to the individual researcher’s preference, making the interpretation of results and reproducibility difficult.

An Unexpected Adverse Reaction is an ADR, the nature or severity of which is not consistent with domestic labeling or market authorization, or expected from characteristics of the drug.

A Serious Adverse Effect is any untoward medical occurrence that at any dose results in death, requires hospital admission or prolongation of existing hospital stay, results in persistent or significant disability/incapacity, or is life threatening