Table 2 |
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Classification of allergic drug reactions: mechanisms, clinical manifestations, and timing of reactions. [7-9] |
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Immune reaction |
Mechanism |
Clinical manifestations |
Timing of reaction |
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Type I (IgE-mediated) |
Drug-IgE complex binding to mast cells with release of histamine, inflammatory mediators |
Anaphylaxis*, urticaria*, angioedema*, bronchospasm* |
Minutes to hours after drug exposure |
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Type II (cytotoxic) |
Specific IgG or IgM antibodies directed at drug-hapten coated cells |
Anemia, cytopenia, thrombocytopenia |
Variable |
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Type III (immune complex) |
Tissue deposition of drug-antibody complexes with complement activation and inflammation |
Serum sickness, vasculitis, fever, rash, arthralgia |
1 to 3 weeks after drug exposure |
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Type IV (delayed, cell mediated) |
MHC presentation of drug molecules to T cells with cytokine and inflammatory mediator release; may also be associated with activation and recruitment of eosinophils, monocytes, and neutrophils |
Contact sensitivity Skin rashes, organ-tissue damage |
2 to 7 days after drug exposure |
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IgE: immunoglobulin E; IgG: immunoglobulin G; IgM: immunoglobulin G; MHC: major histocompatibility complex *These reactions may also be non-immunologically mediated. Adapted from Riedl et al., 2003.6 |
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Warrington and Silviu-Dan Allergy, Asthma & Clinical Immunology 2011 7(Suppl 1):S10 doi:10.1186/1710-1492-7-S1-S10 |
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