Drug eruptions Flashcards
What percentage of drug reactions are cutaneous?
30%
Drug eruptions are becoming harder to diagnose because of polypharmacy. T/F
True - they are also particularly difficult to diagnose in childhood
Immunologically mediated drug eruptions are dose-dependent. T/F
False! - however, non-immune mediated drug eruptions may be dose dependent
What do the different types of immune reaction typically present as in a drug eruption?
Type 1 - urticaria
Type 2 - phemphigus & phemphigoid
Type 3 - purpura/rash
Type 4 - erythema/rash
Give some examples of non-immune mediated drug eruptions.
Eczema drug-induced alopecia (e.g chemo) phototoxicity skin erosion/atrophy (e.g steroids) psoriasis (e.g lithium) pigmentation xerosis (dry skin) or cheilitis (dry lips)
List the most common presentations of drug eruption in descending order.
Erythematous morbilliform/maculopapular rash > Urticarial > Papulosquamous/pustural/bullous > Pigmentation w/ or w/o itch/pain > Photosensitivity
Drug eruptions are usually symmetric. T/F
True (but fixed drug reactions may occur)
Why might the symptoms of a drug eruption not resolve after the drug is withdrawn?
The drug may have a long half life, be retained in tissues or have there may be cross reaction with a similar class of drugs
What are the risk factors for developing a drug eruption?
Being young, female, genetically predisposed, having concomitant disease (viral infections or CF) or having a previous immune reaction/positive skin test
What factors make a drug more likely to cause an immune reaction?
B-lactam containing drugs NSAIDs High molecular weight drugs Hapten (antibody eliciting) forming drugs Topically applied drugs High dosage Long half-life
What type of drug reaction is an erythematous reaction?
Type 4
Erythematous drug reactions are idiosyncratic. T/F
True
Describe the features of an erythematous drug reaction
Mild & self limiting
Symmetrically distributed & widespread
No/minimal involvement of mucous membranes
Commonly itch & mild fever
(NOTE - capable of progressing to life threatening levels)
What is the time of onset of a erythematous drug reaction?
4-21 days after drug exposure
In relation to an erythematous drug reaction, what are some indicators of severity?
Mucous membrane & facial involvement Facial oedema & erythema Widespread, confluent erythema High fever Blisters, purpura or necrosis Lymphadenopathy Arthralgia SOB, wheezing
Give examples of some drugs associated with erythematous drug eruptions
Penicillins Erythromycin Steptomycin Anti-epileptics (carbamazepine) NSAIDs Sulphonamide antibiotics
What type of drug reactions are utricarial?
Type 1 (b-lactam antibiotics, carbazeine) OR direct mast cell degranulation on first exposure (NSAIDs, aspirin, opiates, vancomycin)
What are the two types of pustular reactions?
Acne
Acute generalised exanthematous pustulosis (AGEP)
Give examples of some drugs which may cause an acne drug eruption.
Glucocorticoids Androgens Lithium Isoniazid Pheytoin
Give examples of some drugs which may cause an AGEP drug eruption
Antibiotics
Calcium channel blockers
Anti-malarials
Give some examples of drugs which may cause bullous pemphigoid
ACE inhibitors, penicillin, furosemide
Which drug has the potential to trigger linear IgA disease?
Vancomycin
Describe fixed drug reactions
Well demarcated round plaques
Red & painful
Usually mild when restricted to a single lesion
(NOTE - may present as eczematous lesions, papules, vesicles or urticaria)
Where are fixed drug eruptions most commonly distributed?
Hands, genitals, lips & occasionally oral mucosa
