Drug Reactions Flashcards
Drug Reactions
Cutaneous reactions to drugs occur in up to 8% of hospitalized patients
The 2 most common cutaneous drug reactions are:
Morbilliform/exanthematous eruption
Urticaria
Vary in severity
Trivial to life threatening
Can be :
Expected: penicillin common
Sporadic
Epidemiology– Risk Factors
Women > men Elderly Immunosuppression Number of Drugs Genetic Predisposition
Primary drugs in hospitalized patients: penicillins, sulfonamides, NSAIDS
Mechanism of Drug Reactions
Type 1 IgE dependent drug reactions: • urticaria, angioedema, anaphylaxis
Type 2 Cytotoxic drug-induced
reactions• pemphigus and thrombocytopenia/purpura
Type 3 Immune complex • Vasculitis, serum sickness
Type 4 Delayed Hypersensivity –
most common
• exanthem, fixed and lichenoid drug
Non-immune • overdose, drug interactions
Idiosyncratic • DRESS, drug induced lupus (bad luck)
Basics of Cutaneous Drug
Reactions—Things to consider
Consider ALL drugs as a potential cause of a skin reaction
Prescribed medications, OTC, herbals, etc…
Other helpful clues:
Appearance (symmetric? bullous? Mucous membranes involved?)
Timing relative to drug initiation
Biopsy results
(Allergy testing is of very limited value and generally not recommended)
patch testing better for delay type 4 hypersens
Always document drug reactions in the patient’s chart with the medication and description of the reaction
Timing
Immediate reactions < 1 hour from the last administered dose Examples: urticaria, angioedema, anaphylaxis
Delayed reactions > 1 hour and usually > 6 hours from last administered dose •Occasionally weeks to months after the start of administration Examples: morbilliform eruptions, fixed drug eruption, SJS, TEN, vasculitis
drug historiy
7 I’s
Drug timeline:
Start with the onset as day 0, and work
backwards and forwards
recent hours to weeks
Instilled (eye drops, ear drops)
Inhaled (steroids, beta adrenergic)
Ingested (capsules, tablets, syrup
Intermittent (patients may not reveal medications they take on an intermittent basis unless specifically asked)
Inserted (suppositories)
Incognito (herbs, nontraditional medicine, homeopathic, vitamins, over-the-counter)
Injected (IM, IV)
Exanthematous Drug Eruptions
One of the most common cutaneous drug reaction presentations
Type 4 hypersensivity reaction
“Morbilliform” – refers to rashes that resembles measles
Usually develops 7-14 days after starting a new medication
Most often penicillins, sulfonamides, cephalosporins, anticonvulsants
Begins on trunk and upper extremities becomes confluent
“maculopapular rash”
Mucous membranes spared - no mucous mem involvement
Pruritus and low grade fever
Exanthematous Drug Eruptions
DDx
Viral exanthem - virus more common in peds
very similar morphologically
Often lack peripheral eosinophilia
Most commonly seen in the pediatric population
DRESS - severe facial edema
facial edema
TEN/SJS
mucous membranes involved, annular lesions
Treatment is supportive
Stop the offending agent!!
Topical steroids for symptom relief and vasoconstriction
Resolves within 2 weeks without any complications or sequelae
Drug-induced Urticaria
Type 1 hypersensivity reaction mediated by IgE antibodies
Erythematous and edematous papules and plaques with pruritus
Appear within minutes to days of drug administration
Antibiotics (penicillins, cephalosporins)
Duration of individual lesions is less than 24 hrs
(move around the body)
Urticarial vasculitis lesions last longer than 24 hrs
Acute urticaria <6 weeks
Chronic urticaria > 6 weeks
Angioedema – subcutaneous swelling of the skin or mucosa (eyelids, lips, oropharynx - more serious if airway)
Stop the culprit drug
Consider antihistamines
steroids if itchy
Vasculitis
inflammation and immune complex deposition and actual destruction of some of these
blood vessels under the surface of the skin
Small vessel vasculitis (type 3 reaction, due to immune deposition): Can involve medium sized vessels
Numerous underlying
causes for vasculitis: Idiopathic 50% ofases, Infections (URTI, strep…) 20%, Drugs 15%
Vasculitis
presentation
Clinically: Non blanchable palpable purpura typically on lower extremities Urticaria-like lesions Hemorrhagic blisters
Systemic symptoms: fever, myalgia, headache
Presents within: 7 to 21 days of drug administration
Common drugs: Allopurinol
NSAIDS (oral and topical),
OCPs Antibtiotics (Penicillins, Cephalopsorins, Sulfonamides)
Drug-induced vasculitis
treatment
Stop culprit drug
Topical steroids
Systemic corticosteroids for systemic involvement
Of minimal benefit for localized cutaneous disease
Rule out Kidney and GI involvement
Always do urine analysis and creatinine in anyone
suspected of having vasculitis
AGEP/
Acute Generalized Exanthematous Pustulosis
causes
tx
90% of cases are drug induced Antibiotics (penicillins, cephalosporins, clindamycin) calcium channel blockers, Antimalarials
tx:
Withdraw culprit drug
Topical steroids
Antipyretics
AGEP/
Acute Generalized Exanthematous Pustulosis
presentationton
Arises within 4 days of drug initiation
Small non-follicular sterile pustules within areas of
erythema
Lesions start on face or intertriginous zones
Can get purpura, vesicles, bullae
Mucous membrane involvement in 50% of cases
17% of patients get systemic involvement (liver
and kidney > lung, shown by high WBC count)
Marked leukocytosis
elevated neutrophils and eosinophils
Occasionally hypocalcemia and transient
renal dysfunction
Lesions typically last for 1-2 weeks followed by superficial desquamation
DRESS
Drug reaction with eosinophilia and
systemic symptoms
causes
Drug reaction with eosinophilia and systemic symptoms Common perpetrators: Anticonvulsants (phenytoin, carbamazepine, phenobarbital) Antibiotics (dapsone, sulfonamides, minocycline) Antiretrovirals Allopurinol NSAIDs
