Diagnosis and management of drug hypersensitivity reactions

Classification of drug hypersensitivity reactions

Drug hypersensitivity reactions can be classified as:

- Immediate reactions - occur within 1 hour - type I (IgE-mediated)
- Nonimmediate reactions - occur after more than 1 hour - type IV (T cell-mediated)

Diagnosis of drug hypersensitivity reactions

Prick, patch, and intradermal tests are the most readily available tools.

Determination of specific IgE levels is the most common in vitro method for diagnosing immediate reactions.

New diagnostic tools for for analysis of antigen-specific, cytokine-producing cells include:

- basophil activation test
- lymphocyte activation test
- enzyme-linked immunospot assays

The sensitivity of tests is not 100%; therefore in selected cases provocation tests are necessary.

In the diagnosis of nonallergic hypersensitivity reactions to nonsteroidal anti-inflammatory drugs (NSAIDs), the provocation test with the suspected drug still represents the "gold standard." However, there was no consensus regarding the use of this test in subjects with histories of hypersensitivity reactions to 1 (single reactors) or more (multiple reactors) nonsteroidal anti-inflammatory drugs.



Classification of adverse reactions to drugs: SOAP III (click to enlarge the image).

Management of drug hypersensitivity reactions

Desensitization allows patients to be treated with irreplaceable chemotherapy agents, such as taxanes, platinum salts, and mAbs, to which they have presented hypersensitivity reactions.

Desensitization also permits the use of aspirin in aspirin-sensitive patients undergoing revascularization and in subjects with aspirin-exacerbated respiratory disease.

Another relatively common use of desensitasion is in penicillin allergy.

References:

Diagnosis and management of drug hypersensitivity reactions. Romano A, Torres MJ, Castells M, Sanz ML, Blanca M. J Allergy Clin Immunol. 2011 Mar;127(3 Suppl):S67-73.