Lecture 34 Drug induced eruptions Flashcards
What are the most common cutaneous drug rxns?
morbilliform/exanthematous eruption
urticaria
What are simple and complex reactions when it comes to cutaneous drug rxns?
Simple: ex. exanthematous eruptions, usually no or limited systemic sx (ex. fever), benign and self-limited
starts as macules (pink/red in light skin, purple/brown/black in dark skin) become confluent and later spread symmetrically with scaling and desquamation possibly following, itch may be present
Complex: possible ⇒ fever, arthralgia, SOB, skin tenderness, mucous membrane involvement, angioedema, enlarged lymph nodes, end-organ injury
What are risk factors for drug induced skin reactions?
women, elderly, immunosuppression, number of drugs, genetic predisposition, primary drugs in hospitalized pt ⇒ penicillins, sulfonamides, NSAIDs
What are the reaction timings for drug induced skin reactions?
Immediate: <1 hour from last admin dose, ex. urticaria, angioedema, anaphylaxis
Delayed: >1 hour and usually >6 hours from last admin dose, occasionally weeks to months after start of admin, ex. morbilliform eruptions, fixed drug eruption, SJS, TEN, vasculitis
What is an exanthematous drug eruption (S&S, type of rxn, timeline, common causes, tx)?
S&S: usually first on trunk and then spread to limbs and neck, distributed bilateral and symmetrical maculopapular rash, discrete lesions may merge to form larger patches, may be associated with mild fever and itch, as it improves redness dies away and surface skin peels off
Rxn Type: one of most common is T4 hypersensitivity
Timeline: usually develops 1-2 weeks after starting new med
Common Causes: penicillins, sulfonamides, cephalosporins, anticonvulsants
Tx: stop agent, topical steroids for sx relief and vasoconstriction, resolves within 2 weeks without complications
What are urticarial eruptions (S&S, type of rxn, timeline, common causes, tx)?
S&S: can affect any site, itchy and burning, erythematous edematous papules and plaques often surrounded by vasoconstricted halo (wheals), can have angioedema, lesions often last less than 24 hours and characterized by spontaneous appearance and resolution
Rxn Type: most common T1 hypersensitivity mediated by IgE
Timeline: within minutes to days of drug admin, duration of individual lesions is less than 24 hours, urticarial vasculitis lesions last longer than 24 hours, acute urticaria <6 weeks chronic is longer
Common Causes: antibiotics (penicillins, cephalosporins)
Tx: stop agent, consider oral antihistamines (usually at higher dose than for allergic rhinitis)
What are fixed drug eruptions (S&S, type of rxn, common causes, tx)?
S&S: erythematous or pigmented patch (round or oval), early lesions demarcated erythematous macules, may progress to edematous forming a plaque which may evolve to bulla and then an erosion
lesions usually solitary but may be multiple with random distribution, may become scaly and cause post-inflammatory hyperpigmentation, usually no systemic sx
commonly affects acral surfaces, face/lips, genitals
Rxn Type: likely a localized T4 hypersensitivity
Common Causes: tetracyclines, sulfonamides, NSAIDs, pseudoephedrine
Tx: stop agent, avoid implicated med indefinitely, topical steroids/corticosteroids, generalized blisters require intensive care or burn wound care
What are drug reaction with eosinophilia and systemic symptoms (DRESS) reactions (S&S, diagnosis, common causes, timeline, tx, monitoring)?
S&S: systemic sx (high fever) followed by development of rash, morbilliform but targetoid lesions, blisters and pustules may be there, may be followed by erythroderma or exfoliative dermatitis
facial swelling or mucosal involvement, multiple organ involvement (ex. lymph nodes, blood, liver, lung, GI, kidneys, etc)
Diagnosis: scoring systems ⇒ RegiSCAR, J-SCAR
Common Causes: anticonvulsants (phenytoin, carbamazepine, phenobarbital), antibiotics (dapsone, sulfonamides, minocycline), antiretrovirals, allopurinol, NSAIDs
Timeline: 2-6 weeks after drug started
Tx: stop agent, most causes require prolonged systemic corticosteroids (slow taper over weeks to months)
Monitoring: thyroiditis, hepatitis, TSH and T4 at 3 months, 1 year and 2 years
pancreatitis, development of T1D, chronic exfoliative dermatitis
What is Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN) (S&S, characteristics, classification, timeline, tx)?
S&S: resembles URTI for several days before rash, abrupt onset of tender/painful red skin rash starting on trunk and extending rapidly over hours to days on face and limbs
lesions may be flat, red, diffuse
diffuse erythema, blister development, blisters merge to form sheets of skin detachment exposing red and oozing dermis, painful
Characteristics: mucocutaneous tenderness ⇒ positive Nikolsky sign, skin fragility and erosion/necrosis, skin lesions typically arise first on palms and soles, involvement of oral, genital, ocular mucosa, esophageal, respiratory tract
Class: based on epidermal epidermal detachment
First one if <10% BSA, First-Second overlap if 10-30% BSA, Second if >30% BSA detachment
Timeline: usually occurs 7-21 after start of drug
Tx: stop agent, systemic corticosteroids, involve other care units, possible cyclosporine, etanercept, IVIg
What are the 2 major types of photosensitivity reactions and what do they look like?
Phototoxic: MOST COMMON, appear identical to a sunburn, involves sun-exposed areas ONLY, secondary to tetracyclines, NSAIDs, thiazide diuretics
Photoallergic: secondary to cell-mediated hypersensitivity to an allergen activated or produced by effect of light on a drug, typically appears more eczematous, can result in chronic dermatitis, involves BOTH sun-exposed and non-sun exposed sites, secondary to quinolones, sulfonamides, antimalarials, TCAs
