chapter
Cutaneous Adverse Drug 17
Reaction, Erythema Multiforme,
Stevens–Johnson Syndrome, and
Toxic Epidermal Necrolysis
DEFINITION/OVERVIEW
A spectrum of diseases and clinical signs that vary markedly in clinical appearance
and pathophysiology.
Cutaneous adverse drug reaction (CADR) including exfoliative erythroderma: likely
that many mild drug reactions go unnoticed or unreported; thus, incidence rates for
specific drugs are unknown and most of the facts available on drug-specific reactions
have been extrapolated from reports in the human literature; frequency estimated at
2% (dog) and 1.6% (cat).
Erythema multiforme (EM): most often idiopathic; previously thought to be associ-
ated with drug administration (controversial).
Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN): separate
entities from EM; most likely drug-induced spectrum of dermatoses.
ETIOLOGY/PATHOPHYSIOLOGY
CADR:
Drugs of any type: topical, oral, injectable
Exfoliative erythroderma: most often associated with shampoos and topical
medications
Can occur after the first dose or after weeks to months of administration of the
same drug; typically 5–36 days
Immunologic versus physiologic reaction
Genetic differences in susceptibility
May be dose related and predictable (e.g., corticosteroids and cutaneous atro-
phy) or idiosyncratic (immune mediated, often type 1 hypersensitivity)
Most common: sulfonamides, topicals, penicillins, cephalosporins (Fig-
ures 17.1–17.3).
EM:
Keratinocyte is the target of an immune response resulting in apoptosis (indi-
vidual keratinocyte necrosis)
Reported triggers include antibiotics, food ingredients, infections (bacterial and
viral), and nutraceuticals (Figures 17.4–17.7)
Blackwell’s Five-Minute Veterinary Consult Clinical Companion: Small Animal Dermatology, Third Edition.
Karen Helton Rhodes and Alexander H. Werner.
©2018 John Wiley & Sons, Inc. Published 2018 by John Wiley & Sons, Inc.
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