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Why might the symptoms of a drug eruption not resolve after the drug is withdrawn?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
When the offending drug is stopped what happens to a fixed drug reaction?
Persistant pigmentation
Give examples of drugs which are commonly associated with fixed drug eruptions
Tetracycline, doxycycline, paracetamol, NSAIDs, Carbamazepine
Give examples of severe cutaneous reactions
Stevens-Johnson syndrom (SJS)
Toxic Epidermal Necrolysis (TEN)
Drug reaction with eosinophilia and systemic symptoms (DRESS)
Acute generalised exanthematous pustulosis (AGEP)
Describe severe cutaneous reactions
SJS - blistering in oral & genital mucosa
TEN - looks like a whole body burn, positive precursky skin, hypothermic, risk of sepsis
DRESS - facial oedema, lymph node swellings, high temperatures
What are the acute and chronic signs of phototoxicity?
Acute - skin toxicity, systemic toxicity, photodegredation
Chronic - pigmentation, photoaging, photocarcinogenesis
What is a photocutaneous drug reaction?
A non-immunologically mediated skin reaction which can occur in any individual providing there is enough photo-reactive drug & the appropriate wavelength of light
Which wavelengths of light typically cause photocutaneous drug reactions?
UVA and visible light
How may increased sensitivity to sunlight occur without the use of phototoxic drugs?
Immunosuppression may increase sensitivity to sunlight
What are the major patterns of cutaneous phototoxicity? Give an example of a drug which may cause each pattern
Immediate prickling with delayed erythema and pigmentation (amiodarone)
Exaggerated sunburn (thiazides)
Exposed telangiectasia (calcium channel antagonists)
Delayed (3-5 day) erythema and pigmentation (psoralens)
Increased skin fragility (amiodarone)
What is the most common pattern of cutaneous phototoxicity?
Exaggerated sunburn
List some drugs which cause phototoxicity
NSAIDs Psoralens Antifungals (voriconazole) Thiazide diuretics Antibiotics Amiodarone
When is skin testing absolutely not indicated in the context of cutaneous drug reactions?
Type 3 and type 4 immune reactions
Immunocompromised patients are more likely to suffer severe cutaneous reactions. T/F
True
How might a drug reaction be managed?
Discontinuing use of drug
Topical steroids
Antihistamines
