Adverse Drug Reactions
The WHO definition of an adverse drug reaction has been in existence for the past 30 years: "a response to a drug that is noxious and unintended and occurs at doses normally used in man for the prophylaxis, diagnosis or therapy of disease, or for modification of physiological function".
A more recent definition was: "An appreciably harmful or unpleasant reaction, resulting from an intervention related to the use of a medicinal product, which predicts hazard from future administration and warrants prevention or specific treatment, or alteration of the dosage regimen, or withdrawal of the product." 1
This definition includes the concept of error in the definition of an adverse drug reaction and highlights opportunities of preventive action to avoid adverse effects. Preventing ADRs is also therefore important. Between 30 and 80% of ADRs may be preventable 2 and a UK study found that two thirds of adverse drug reactions caused by non-steroidal anti-inflammatory drugs which contributed to hospital admission were preventable.3
Adverse drug reactions can range from the relatively non-dangerous (e.g. mild drowsiness), the troublesome (e.g. chronic dry cough), the serious (e.g. haemorrhage, fitting) and even death. However, serious side effects of medicines are less common, and death very rare.
The history of adverse drug reactions is over 2000 years old.4 In 10th century Italy, the medical school of Salerno was empowered to hang offending druggists if they were found to have sold a poison or noxious drug. Frederic the Great dictated that the life of a seller of a magic elixir or love potion would be forfeit if a purchaser died. As late as 1954, 100 people died in France using a contaminated boil treatment. However, the seminal moment in drug safety was the thalidomide case in the 1960's when large numbers of children were born with limb deformities. Following this incident major changes occurred in the monitoring of the ongoing safety of medicines.
In the UK, this lead to the formation of the Committee on Safety of Drugs (now known as the Committee on Safety of Medicines). They, in combination with the Medicines Control Agency, operate the Yellow Card Scheme which accepts spontaneous reports of adverse drug reactions. The blacktriangle is part of the Yellow Card and is explained in more detail here.
1. Edwards RI, Aronson JK. Adverse Drug reactions:definitions, diagnosis, and management. The Lancet 2000;356:1255-59
2. Pearson TF et al. Factors associated with preventable adverse drug reactions. Am J Hosp Pharm. 1994; 51: 2268-2272
3. Cunningham G et al. Drug-related problems in elderly patients admitted to Tayside hospitals, methods for prevention and subsequent reassessment. Age and Ageing 1997; 26: 375-382
4. Davies DM. 2000 years of adverse drug reactions. Adverse Drug Reaction Bulletin 1999;199:759-762.