Drug allergy classification: Difference between revisions
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==Classification Based on Reaction Type== | ==Classification Based on Reaction Type== | ||
One type of [[classification]] of drug allergies, is based on the type of [[autoimmune]] process. This is the same type of classification that is used for other types of [[immunological]] reactions, and is based on the Gell and Coombs system. Drugs usually cause type III and type IV reactions, however certain medications such as penecillin, can cause all four. | One type of [[classification]] of drug allergies, is based on the type of [[autoimmune]] process. This is the same type of classification that is used for other types of [[immunological]] reactions, and is based on the Gell and Coombs system. Drugs usually cause type III and type IV reactions, however certain medications such as penecillin, can cause all four. | ||
*[[Type I hypersensitivity reaction]]: Immediate onset and primarily caused by the [[IgE]], [[basophils]], and [[degranulation]] of mast cells. | *[[Type I hypersensitivity reaction]]/ IgE mediated: Immediate onset and primarily caused by the [[IgE]], [[basophils]], and [[degranulation]] of mast cells. | ||
*Type II | *Type II antibody mediated cell destruction: Delayed onset reaction caused by [[antibodies]], mediated by [[IgG]] mediated destruction of cells. | ||
*Type III | *Type III immune complex deposition: Delayed in onset and caused by IgG [[immune complex]] formation and deposition, and [[complement]] activation. | ||
*Type IV hypersensitivity reaction: [[T-cell]] mediated delayed onset reaction. | *Type IV cell mediated/ delayed-type hypersensitivity reaction: [[T-cell]] mediated delayed onset reaction. | ||
==References== | ==References== | ||
{{reflist|2}} | {{reflist|2}} | ||
Revision as of 16:05, 16 August 2012
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Charmaine Patel, M.D. [2]
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Overview
Drug allergies are classified using two main sets of criteria. One is set forth by the World Allergy Association, and classifies the reaction as to whether it occurs within one hour of treatment, or after one hour. The other set of criteria are based on the type of immunologic reaction that occurred and the mediators involved.
Classification Based on Timing of Symptoms
There are recommendations on the classification of drug allergy reactions based on the World Allergy Association (WAO) guidelines.[1] The two categories of classification are based on whether the reaction occurs less than one hour of medication administration, or more than one hour afterwards.
- Immediate- these reactions occur within one hour, and are most likely due to IgE mediated type I reactions. At times, type I reactions can occur after one hour if the absorption of the drug is delayed, for example due to an oral medication or ingesting a medication with food. These types of reactions have the risk of anaphylaxis if the patient is re-exposed.
- Delayed- these reactions occur after one hour, although most occur 6 hours after the administration of the drug, and some occur up to 7 to 10 days after treatment. Some reactions can even occur days after the treatment has been stopped.
Classification Based on Reaction Type
One type of classification of drug allergies, is based on the type of autoimmune process. This is the same type of classification that is used for other types of immunological reactions, and is based on the Gell and Coombs system. Drugs usually cause type III and type IV reactions, however certain medications such as penecillin, can cause all four.
- Type I hypersensitivity reaction/ IgE mediated: Immediate onset and primarily caused by the IgE, basophils, and degranulation of mast cells.
- Type II antibody mediated cell destruction: Delayed onset reaction caused by antibodies, mediated by IgG mediated destruction of cells.
- Type III immune complex deposition: Delayed in onset and caused by IgG immune complex formation and deposition, and complement activation.
- Type IV cell mediated/ delayed-type hypersensitivity reaction: T-cell mediated delayed onset reaction.