Felis ISSN 2398-2950
Drug eruption
Synonym(s): Drug reaction, Drug allergy, Dermatitis medicamentosa
Contributor(s): Rosanna Marsella, David Scarff
Introduction
- Cause: idiosyncratic reaction to the use of a drug.
- Signs: may mimic any other cutaneous reaction pattern.
- Diagnosis: history of drug administration and response to drug withdrawal.
- Treatment: supportive care and drug withdrawal.
- Prognosis: mostly good.
Pathogenesis
Etiology
- Any drug can cause any reaction pattern.
Pathophysiology
- Mechanism of drug reactions is poorly understood.
- There may be the induction of an immune response or abnormality of drug metabolism in an individual.
- Hypersensitivity reaction if the drug, a carrier molecule or a metabolite acts as an antigen.
- Hypersensitivity reactions can be types 1,2,3 or 4.
- Type 1-anaphylaxis or urticaria.
- Type 2-cytotoxic reactions eg erythema multiforme.
- Type 3-immune complex development → vasculitis.
- Type 4-delayed type eg contact reactions.
- Pseudoallergy where a drug causes mast cell or basophil degranulation in a non-immune-mediated fashion.
- Autoimmunity: drugs may cause an alteration in autoantigens, there may be molecular mimicry or antigen-independent T-helper cell activation.
- Rarely drug metabolites are directly toxic to skin cells, possibly as a consequence of a genetic enzyme deficiency in an individual.
Timecourse
- Most reactions occur within 1-3 weeks of drug exposure.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Noli C, Koeman J P, Willemse T (1995) A retrospective evaluation of adverse reactions to trimethoprim-sulphonamide combinations in dogs and cats. Vet Q 17 (4), 123-128 PubMed.
- Mason K V (1990) Cutaneous drug eruptions. Vet Clin North Am Small Anim Pract 20 (6), 1633-1653 PubMed.
- Nesbitt G H (1986) Cutaneous drug reactions in small animals. Clin Dermatol 4 (1), 190-193 PubMed.
Other sources of information
- Rosencrantz W S (1993) Cutaneous drug reactions. In: Current Veterinary Dermatology - The Science and Art of Therapy. Eds C E Griffin, K W Kwochka & J M MacDonald. St. Louis: Mosby Yearbook, pp 154-164. ISBN: 0 8016 3384 2. (Lucid overview of subject.)