Cutaneous drug eruptions Flashcards
Urticaria
Type 1 anaphylactic reaction
Pemphigus and pemphigoid
Type II cytotoxic reaction
Purpura/rash
Type III immune complex mediated reaction
T-cell mediated erythema/ rash
Type IV cell mediated delayed hypersensitivity reaction
Are immunologically mediated reactions dose dependent?
No
Eczema immunologically mediated?
No
Are eczema, drug induced alopecia, phototoxicity, skin erosion/atrophy (from topically applied 5FU/steroids), Psoriasis, pigmentation, cheilitis, xerosis dose dependent?
Yes, because these are not immunologically mediated
Concommittent disease that may make you more likely to have drug eruption?
Viral infections (HIV/EBV/CMV) Cystic fibrosis
Why can NSAIDs cause reaction?
They have beta lactam ring –> this is a risk
Most common type of drug eruption?
Xanthematous drug reaction
What type of hypersensitivity is a xanthematous drug reaction?
Type IV (T cell mediated)
When would you get xanthematous reaction?
4-21 days after taking first drug
Pattern of xanthematous drug reaction distribution?
Wide spread, symmetrically distributed
Mucous membranes usually spared
Itch is common
Fever is common
(can progress to severe)
Indicators of a potential severe reaction? (xanthematous)
Involvement of mucous membrane and face. • Facial oedema & erythema. • Widespread confluent erythema. • Fever (>38.50C). • Blisters, purpura, necrosis. • Lymphoadenopathy, arthalgia. • Shortness of breath, wheezing.
PECANS SAP
xanthematous reaction
Penicillins Erythromiciin Chloramphenicol Allopurinol NSAIDS Sulfonamide abx
Streptomicin
Anti-epileptics
Phenytoin
Urticaria usually mediated by which Ig?
IgE
IgE
Usually an immediate IgE- mediated hypersensitivity reaction (Type I) after rechallenge with drug (β-lactam antibiotics, carbazepine, many other drugs).
Or
– Direct release of inflammatory mediators from Mast cells on first exposure (aspirin, opiates, NSAIDs, muscle relaxants, vancomycin, quinolones)
Drugs which could cause acne?
PAILS
Phenytoin Androgens Isoniazid Lithium Steroids
Drugs which could cause acute generalised exanthematous pustulosis? (AGEP)
(CAbAm)
Calcium channel blockers
Antibiotics
Antimalarials
Drug induced bullous pemphigoid?
FAP …. lol
Furosemide
ACE inhibitors
Penicillin
Drug which could trigger linear IgA disease?
Vancomycin
Describe a fixed drug eruption appearance?
Well demarcated, round/ovoid plaque
Red, painful
Hands, genitalia, lips, occasionally oral mucose
Will a fixed drug eruption resolve when you stop taking that drug?
Yes but you have persistent pigmentation
-can reoccur on the same site on re-exposure to the drug
Drugs associated with fixed drug eruptions?
Try Doing Nothing Cause Paracetemol
Tetracylcine Doxycyline NSAIDS Carbamazepine Paracetemol
Drugs which would cause SJS/TEN
Suck Candy Cause Nobody Pays Today
Sulfonamide Cephalosporins Carbamezepine NSAIDs Phenytoin Tramadol
Drug reaction with eosinophilia and systemic symtpoms?
(VAANS
Vancomycin Allopurinol Anti-convulsants NSAIDs Sulfonamides
Are phototoxic cutaneous drug reactions immunologically mediated?
No, they will arise in anyone if there is enough appropriate drug and the appropriate wavelength of light
Waveband of light that usually causes phototoxic drug reaction?
UVA/visible light
Can occur indoors through window and glass
When you react to psoralen, when would you develop erythema and pigmentation?
3-5 days after
Which drugs will exxagerate sunburn? (QT)
Qunine, thiazides
Which drugs will give you telangiectasia in the sun? (CT)
Calcium channel blockers cause Telangiectasia
Immediate prickling with delayed erythema and pigmentation?
Chlorpromazine, amiodarone
Why is skin testing NOT indicated for serum sickness reactions (TYPE III) or for T-cell mediated reactions (TYPE IV)?
Can potentially trigger SJS, TEN and DRESS
Test if you think it is a suspected allergic contact dermatitis (type IV)?
Patch and photopatch test
Management of cutaneous drug reaction?
Discontinue the drug (if possible). Use an alternative.
• Topical steroids may be useful.
• Antihistamines may be useful.
• Allergy bracelets are useful for some drugs.
• Drug eruptions should be reported via the Yellow Card scheme (Medicines and Healthcare products Regulatory Agency)
