Drug Eruptions Flashcards
Are immunologically mediated reactions dose dependent?
No
What skin conditions are caused by type 1 hypersensitivity reactions?
urticaria
What skin conditions are caused by type 2 hypersensitivity reactions?
pemphigoid and pemphigus
How do drug eruptions most commonly present?
exanthematous (rash is a prominent manifestation) is the most common type of drug hypersensitivty reaction. (also known as morbiliform or maculopapular)
How else can drug eruptions present?
urticarial in 5-10% papulosquamous (both papules and scales) pustular bullous pigmentation itch/pain photosensitivity
When should you consider a drug eruption?
in any patient who is taking medication and develops a symmetric skin eruption of sudden appearance
What are the risk factors for the development of drug eruptions?
age- young adults more common than infants or elderly
female gender
concomitant disease- viral infetions or cystic fibrosis
immune status- previous reactions
route
What types of drugs are likely to cause eruptions?
B-lactam compounds; NSAIDs
high molecular weight
hapten forming drugs
What is a hapten?
Haptens are small molecules that elicit an immune response only when attached to a large carrier such as a protein; the carrier may be one that also does not elicit an immune response by itself.
What type of hypersensitivity is involved in exanthematous drug eruptions?
Type 4 (T-cell mediated delayed type)
What is the onset of an exanthematous drug eruption after first taking the drug?
4-21 days
What would indicate that the exanthematous drug eruption is potentially severe?
involvement of mucous membrane and face facial oedema and erythema widespread confluent erythema fever blisters, purpura, necrosis lymphadenopathy, arthralgia SOB and wheezing
What could indicate that the mucous membranes have been involved in the exanthematous drug eruption?
mouth ulcers- dysphagia
difficulty passing urine
What are the two ways that an urticarial drug eruption can take place?
Usually- IgE mediated after rechallenge with drug
But- direct release of inflam mediators from mast cells on first exposure–NSAIDs and aspirin
What are the 2 types of pustular drug eruption?
acne
acute generalied exanthematous pustulosis (AGEP)
What drugs can induce bullous pemphigoid?
ACEIs, penicillin and furosemide
What is the characteristic of a fixed drug eruption?
Recurs on the same sites on re-exposure to the drug
What is a severe cutaneous adverse reaction?
They combine cutaneous and systemic symptoms
Give 4 examples of severe cutaneous adverse reactions
Stevens-Johnson syndrome
Toxic epidermal necrolysis
Drug reaction with eosinophilia and systemic symptoms (DRESS)
Acute generalised exanthematous pustulosis (AGEP)
Phototoxic cutaneous drug reactions are immunologically mediated. T/F
False
How can phototoxicity present?
exaggerated sunburn immediate prickling with delayed erythema and pigmentation exposed telangiectasia delayed 3-5days erthema and pigmentation increased skin fragility
