SELECTED ARTICLES FROM THE RECENT LITERATURE 2006

11/14/06

Hypersensitivity reactions to anticoagulant drugs

Summary
Background - Hypersensitivity/allergic reactions to anticoagulant (AC) drugs are unusual but do have major impact on treatment decisions when they do occur.

Findings - Bircher et al of the University Hosp in Basel, Switzerland reviewed aspects of AC hypersensitivity. The most common of these reactions are erythematosus plaques occurring with delayed onset after subcutaneous injection of heparin agents. Occasionally, these evolve into more generalized macolopapular eruptions. Other hypersensitivity reactions to AC are much less common but can be life threatening such as the skin necrosis associated with heparin-induced thrombocytopenia.

Evaluation includes a careful history and then skin testing with the suspect agent, looking for immediate and delayed skin test reactions when appropriate. Such approaches are helpful (though not completely diagnostic) in cases of heparin or hirudin induced urticaria/anaphylaxis or the delayed onset plaques. However, skin tests should not be done in cases where skin necrosis reactions have recently occurred. Skin tests are also not indicated in cases of anaphylactoid reactions to products such as dextrans or hydroxyethyl starch.

Reference
Allergy 2006;61:1432-40

Editor's Comments
The discussion in this article is worth reading in light of the increasing, extensive use of AC and plasma expander drugs in clinic practice. Heparin-induced thrombocytopenia is a particularly common adverse effect.

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