Mod 2 week 1 Drug reactions

What % hospital inpatients are affected by drug reaction? How many of these affect skin?
10-20%. 1/7
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Groups most at risk of drug reaction?
1. Elderly 2. Multiple meds 3. HIV
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Common drugs implicated?
NATASHA NSAIDS, Abx, TK inhibitors (chemo)/thiazides, antiepileptics, sulphur drugs, HIV meds, allopurinol
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Classification of drug reactions? 2. Which is more common
Allergy. Intolerance. Intolerance much more common (90%)
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Drug rash patterns 6
1. Urticaria 2. FDE (rare) 3. Exanthem (most common) 4. DRESS 5. AGEP 6. SJS/TEN
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Latency for each pattern
Urticaria 24-36h, rechallenge - 5-20min. FDE 1-2 wk after first exposure, then within 24h. AGEP 1-5d. Exanthem 7-10d (if already sensitised can be 1-2d). SJS/TEN 1-2 week. DRESS 3wk-3mo.
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Describe drug-induced exanthem. Culprits. Risk if drug not stopped
Morbilliform drug rash, trunk & extremities (often spares face and pressure areas), may or may not itch. Fades with desquamation/hyperpig. Abx/NSAIDs. Erythroderma
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How to differentiate from viral exanthem?
Viral tends to start on face/acral then spread to trunk. Viral tends to have *** fever/sore throat/GI sx/cough etc. Viral not usually itchy. If mucous membranes think viral.
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Treatment of drug exanthem
Stop drug. Emollient and topical steroid if itchy.
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FDE describe. Location. Culprits. Leaves behind?
Pruritic red oval patch, can develop central blister. Upper torso, hands, lips, genitals. Recurs same site each time patient takes the drug. NSAIDs/abx i.e. drugs that are taken intermittently. Can develop more patches with more exposure. hyperpig
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AGEP acute generalised exanthematous pustulosis. Location? Describe? Risk if drug not stopped. Rx
Rapid development of sheets of sterile pustules in flexures -> spreads to trunk. Pain, erythema, pustules, oedema, fever. Raised neut. Culprits - abx/nsaids. AKI. Stop drug, topical/oral steroid
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Describe DRESS drug reaction with eosinophilia and systemic symptoms. Rx
Rash - often urticated papular exanthem - often dusky and purpuric, can get exfoliation, facial oedema. Eosinophilia and atypical lymphocytes + abnormal LFTs, lymphadenopathy, liver damage, pneumonitis, myalgia. Topical and oral steroids
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SJS/TEN - define each in % of skin involved. Mortality rate in TEN
Spectrum. SJS<10% epidermal involvement. TEN >30%, sheet like erosions. EM also considered part of spectrum but usually infectious cause so different entity. 40-60%
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SJS/TEN what is it. Culprits
Hypersensitivity reaction to drug. Mucocutaneous - blistering and epithelial loss, causing acute skin failure. Abx, allopurinol, antiepileptics
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What is histological pattern
Lichenoid with interface dermatitis
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How does TEN/SJS start?
1-2 weeks after drug. URTI sx - sore throat/mouth, gritty eyes, fever, rash.
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Describe rash of TEN/SJS
Early lesions dusky/purpuric - confluent macules. Target lesions on acral skin. Mucositis (can get scarring keratitis - blindness, mouth, bronchial - often need ventilator). Blistering epidermal loss (Nikolskys positive) leaving dermis exposed.
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what scoring system is used for TEN?
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Rx SJS/TEN. What to tell relatives?
Supportive care in burns unit/ITU. oral/IV steroid controversial, IVIG (limited evidence), ciclosporin (T-cell mediated disease). Tell 1st degree relatives they may have higher chance of reaction with the drug
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Drug induced urticaria Ix
drug-specific IgE, skin *****, intradermal testing, challenge testing.
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Drug induced urticaria - is death from anaphylaxis common. Rx
No. Withdraw drug - improvement seen within 24-48h. May need oral/IV steroid, AH, s/c adrenaline.
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Drug-induced urticaria - culprits
NSAIDs, aspirin, penicillin and other beta lactams
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Causes of drug-induced pruritus. What might you see on skin
Opioids, NSAIDs, ACEi, stating. Nodular prurigo.
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Symmetrical drug-related intertriginous and flexural exanthem
symmetrical eruption on buttocks, thighs, axillae, elbow, flexures, neck. Sharp demarcation. Spares palms, soles, mucosa and face.
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Lichenoid drug eruption - presentations 2
LP or cutaneous lupus erythematosus.
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What % of LP and LE are caused by drugs
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Onset after exposure
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Is drug-induced LE clinically more like SLE than idipathic cutaneous LE?
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Ix lichenoid drug reaction?
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Drug induced acneiform eruption - how different to acne?
MONOMORPHIC papules and pustules. no comedones/cysts. Sudden onset 1-2 week after starting medication.
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Acneiform causes?
Corticosteroids, androgens/anabolic steroids, contraceptives, lithium, phenytoin, valproate, ciclosproin
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Drug induced photosensitivity - phototoxcicity - immediate burning on sun exposed sites. Causes
Tetracyclines, isotretinoin, NSAIDs, statin, frusemide, thiazide
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Drug-induced pigmentation causes 7
1. prostaglandin in eye drop - periocular pigmentation & hypertrichosis 2. Minocycline 3. Phenothiazines 4. Antimalarials - hydoxychloroquine 5. Amiodarone - slate grey, dose dependent 6. Heavy metals - gold, silver, iron 7. Hydroquinone
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Hydroxychloroquine pigmentation describe
Grey/blue pigmentation of shins, can start years after starting drug, fades slowly and incompletely
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What does hydroquinone cause?
Bleaching agent used in lightening creams. Causes exogenous ochronosis -> confetti like pigmentation, can start years after drug started.
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Drug induced bullous disorders types 5
Bullous pemphigoid. Linear IgA. Pemphigus. Pseudoporphyria. TEN
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Drug-induced vasculitis describe
leukocytoclastic rash
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Rashes with chemotherapy? 3
Papulopustular eruption secondary to EGFR inhibitors e.g. Cefutiximab for colorectal ca. Palmoplantar erythrodysaesthesia secondary to doxorubicin/taxels. Flagellate erythema
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1. Papulopustular eruption caused by EGFR inhibitors - what % of patients get this. Distribution. Resembles. Latency. Prevention
90%. Seborrhoeic. NOT COMEDONAL. Bad rosacea. 7-10d. Prophylactic doxy
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2. Palmoplantar erythrodysaesthesia caused by doxorubicin, docetaxel
Tingling or burning of palms/soles -> acral erythema -> desquamation
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3. Flagellate erythema causes
Bleomycin shiitake mushrooms, jellyfish stings
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Nicorandil drug reaction
Genital or oral ulceration.
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Graft vs host disease after stem cell transplant - types
Acute (within first 100d), chronic (>100d after tx)
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Acute GVHD describe. Bloods. Other sx. Rx . Histology
Diffuse morbilliform eruption. ACRAL -> widespread. Abnormal LFT. Diarrhoea, abdo pain. Systemic steroids. Lichenoid
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Chronic GVHD describe - 2 forms. Rx
1. Sclerodermatous. 2. Lichen planus-like. Extracoroporeal photophoresis
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Groups most at risk of drug reaction?


1. Elderly 2. Multiple meds 3. HIV

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Common drugs implicated?


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Classification of drug reactions? 2. Which is more common


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Card 5


Drug rash patterns 6


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