Classification of Adrs
Classification of Adrs
Four classification systems are uscd to describe ADRs (1, 7).
ADRs can be classified according to thepharmacologic effect of the drug-Type A, B, C, and D reactions.
Type A reactions are exaggcrated but normal pharmacologic actions of a drug. They arc predictable and dose dependent.
Type B reactions are not predictable given the known pharmacologic action of a drug and are not dose related. Many of these Type B reactions are hypersensitivity or immune-based. These reactions can bc further subdivided into type 1 (IgE-mediated rcaction), II(1gG or IgM-mcdiated cytotoxic reaction), 111 (IgGmediated immune complex reactions), and TV (ccllmediated immune reaction).
Typc C reactions are those due to long-term use of a drug.
Typc D reactions are delayed drug effects, such as due to carcinogenicity or teratogenicity.
ADRs can also be classified according to the dose relationship, i.e., dose-related and non-dose-related reactions.
Another classification system is based on thc causal relationship between the reaction and thc drug. One of the most widely used causality classifications is based on Naranjo’ s descriptions. These categories include definite (drug is likely the true cause), probable (drug is the apparent cause), possible (drug appears to be associated), and remote (drug is not likely to be the cause).
The fourthclassification system is based on degree of injury or severity of reaction. There are mild reactions (temporary discomfort and tolerable), moderate (significant discomfort), and severe (potentially life threatening or causing permanent disability or death).
Four classification systems are uscd to describe ADRs (1, 7).
ADRs can be classified according to thepharmacologic effect of the drug-Type A, B, C, and D reactions.
Type A reactions are exaggcrated but normal pharmacologic actions of a drug. They arc predictable and dose dependent.
Type B reactions are not predictable given the known pharmacologic action of a drug and are not dose related. Many of these Type B reactions are hypersensitivity or immune-based. These reactions can bc further subdivided into type 1 (IgE-mediated rcaction), II(1gG or IgM-mcdiated cytotoxic reaction), 111 (IgGmediated immune complex reactions), and TV (ccllmediated immune reaction).
Typc C reactions are those due to long-term use of a drug.
Typc D reactions are delayed drug effects, such as due to carcinogenicity or teratogenicity.
ADRs can also be classified according to the dose relationship, i.e., dose-related and non-dose-related reactions.
Another classification system is based on thc causal relationship between the reaction and thc drug. One of the most widely used causality classifications is based on Naranjo’ s descriptions. These categories include definite (drug is likely the true cause), probable (drug is the apparent cause), possible (drug appears to be associated), and remote (drug is not likely to be the cause).
The fourthclassification system is based on degree of injury or severity of reaction. There are mild reactions (temporary discomfort and tolerable), moderate (significant discomfort), and severe (potentially life threatening or causing permanent disability or death).
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