Definitions And Classification Of Adverse Drug Reactions

An ADR can be defined as follows (9):

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.

It is therefore important to note that patients who have taken overdoses, have misused drugs, and develop symptoms of disease recurrence as a result of poor compliance are excluded by this definition.

ADRs vary widely in their clinical manifestations and severity. ADRs can affect any organ system and can mimic any disease process, hence the importance of including drug-related disease in the differential diagnosis in every patient presenting with new symptoms

(10). Fortunately, the majority of ADRs are mild and do not require specific therapy. However, a significant percentage, as indicated previously, can be serious and fatal. A serious adverse event has been defined by the International Conference on Harmonisation

(11) as any untoward medical occurrence that at any dose:

1. Results in death,

2. Is life threatening,

3. Requires hospital admission or prolongation of stay in hospital,

4. Results in persistent or great disability, incapacity, or both,

5. Is a congenital anomaly, birth defect, or both.

There are many different classifications for ADRs; the simplest and most frequently used classification is that proposed by Rawlins and Thompson (12). ADRs are divided into two types: type A ("augmented") and type B ("bizarre") reactions. Type A ADRs are predictable from the known pharmacology of the drug, have a good dose-response relationship, and may improve on dose reduction. Type B, or idiosyncratic reactions, are uncommon (20% of all adverse reactions), cannot be related to the known pharmacological properties of the drug, do not show a simple dose-response relationship, and cannot be reproduced in animal models. A more recent classification has attempted to relate ADRs to the dose, timing of the ADR, and susceptibility (9).

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The term vaginitis is one that is applied to any inflammation or infection of the vagina, and there are many different conditions that are categorized together under this ‘broad’ heading, including bacterial vaginosis, trichomoniasis and non-infectious vaginitis.

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