3) Drug Eruptions Flashcards
Exanthematous (morbilliform) drug reactions
- 2% of individuals exposed to drugs
- Accounts for 95% of cutaneous reactions
- Highest rates associated with antibiotics
Exanthematous (morbilliform) drug reactions mechanism
- Possibly a delayed type T-cell mediated immune reaction
- Genetic predisposition, underlying viral disease, and administration of multiple medications
Exanthematous (morbilliform) drug reactions characteristics
- Erythematous maculopapular rash in trunk and proximal extremities
- Developing within 5-14 days
- May occur as early as 2-3 days in previously sensitized patients
Exanthematous (morbilliform) drug reactions symptoms
- Pruritis (usually in legs or area of dependence)
- Low grade fever
- Mild eosinophilia
- Mucosal involvement is absent
Exanthematous (morbilliform) drug reaction diagnosis
- Resolution in 7-14 days or with discontinuation of offending drug
- DDx includes viral & bacterial exanthems, systemic disease rashes, and cutaneous diseases
Exanthematous (morbilliform) warning signs of more serious condition
- Erythroderma
- High fever
- Facial edema
- Mucositis
- Skin tenderness
- Blistering
Exanthematous (morbilliform) drug reaction treatment
- Removal of offending drug
- Symptomatic relief with topical corticosteroids and oral antihistamines
- High potency topical corticosteroid applied once or twice daily for pruritic relief (or oral histamines until subsides)
Exanthematous (morbilliform) drug reaction eliciting drugs
- Penicillin
- Cephalosporin
- Macrolides
- Quinolones
- Tuberculostatic
- Sulfonamides
- Anticonvulsants
- NSAIDs
- Paracetamol
- RTIs
Acute generalized exanthematous pustulosis (AGEP)
- 1-5 per million, rare
- 90% of cases caused by drugs
- Most often antibiotics, antifungals, calcium channel blockers, and antimalarials
Acute generalized exanthematous pustulosis (AGEP) mechanism
- Thought to be T-cell mediated neutrophilic inflammation involving drug specific CD4/8, cytokines, and chemokines
Acute generalized exanthematous pustulosis (AGEP) characteristics
- Dozens to hundreds of nonfollicular, sterile pustules beginning on the face and extending to trunk and limbs
- May occur a few hours to days after drug has been introduced
- Median time for antibiotics was one day while others were 11 days
Acute generalized exanthematous pustulosis (AGEP) signs/symptoms
- Dozens to hundreds of pinhead-sized pustules
- Fever > 38 ˚ C
- Leukocytosis w > 7,000 neutrophils
- Pustular smear negative for bacteria
Acute generalized exanthematous pustulosis (AGEP) diagnosis
- Typical signs (one or more) presenting with an acute, febrile pustular eruption a few hours to days after starting a new drug
Acute generalized exanthematous pustulosis (AGEP) DDx
- Generalized acute pustular psoriasis
- Stevens-Johnson syndrome/toxic epidermal necrolysis
- Sneddon-Wilkinson disease
- Bullous impetigo
AGEP treatment
- Removal of offending drug, supportive cate, and symptomatic treatment
- Supportive care involves moist dressings and antiseptic solutions during pustular phase
- Symptomatic relief includes medium potency topical corticosteroids and oral antihistamines
AGEP eliciting drugs
- Aminopenicillins
- Macrolides
- Quinolones
- Sulfonamides
- Hydroxychloroquine
- Terbinafine
- Diltiazem
New onset urticaria
- Common (20% of population)
- Allergic reactions to medication, food, or insect bites/stings
- Common viral and bacterial infections
- Classified as acute (< 6 weeks) or chronic (> 6 weeks) –> 2/3 fall under acute classification
New-onset urticaria mechanism
- Involves cutaneous mast cells in the superficial dermis which release histamine and vasodilatory mediators causing itching and localizing swelling
New-onset urticaria lesions
- Intensely pruritic appearing as circumscribed, raised, erythematous plaques with central pallor
- Shape may be round, oval, or serpinginous ranging from < 1cm to several cm
- May enlarge and usually disappear within 24 hours
New-onset urticaria characteristics
- Transient w/out residual affect
- Non painful, but pruritic lesions
- With or without angioedema
- May affect any area of the body
- Many associated triggers as seen in chart
- Infections are associated with over 80% of acute urticarial reactions in pediatric population
- Antibiotics are most frequently implicated in
- causing IgE-mediated urticaria (beta-lactams)
New-onset urticaria diagnosis
- Clinical one based on your H&P as well as characteristic lesions
- Resolution of individual lesions from the eruption in about 24
hours - DDx includes atopic dermatitis, contact dermatitis, insect bites, bullous pemphigoid, or erythema multiforme minor, etc.
New-onset urticaria must r/o anaphylaxis
- Generalized, rapid onset and evolution
- Related to an allergen which may resolve on its own or require respiratory and/or CV support along with emergency treatment
New-onset urticaria treatment
- Initial treatment: short term relief of pruritus and angioedema if present
- Two-thirds of cases are self limiting and will resolve spontaneously
- Second generation H1 antihistamines are first line treatment drugs in mild cases
- If symptoms are moderate to severe, then addition of an H2 antihistamine is recommended
- Patients with prominent angioedema and persistent symptoms despite treatment with H1 & H2 antihistamines, then a glucocorticoid should be added in a short term dose (~5-7 days)