Drug Reactions Flashcards
What is the most common type of drug reaction
Exanthematous drug reaction
Presentation of exanthematous drug reaction
erythematous confluent macules
Fever
timeline of exanthematous drug reaction
anytime up to 2-3 weeks after administration
drugs causing an exanthematous reaction
penicillins
carbamazepine
NSAIDs
allopurinol
What is drug-induced urticaria
drug-induced hives - skin reaction causing itchy welts and blotches
What life-threatening symptoms can drug-induced urticaria occur with
angioedema
timeline of drug-induced urticaria
within 36h of administration
within minutes on re-challenging with the drug
drugs causing drug-induced urticaria
penicillins
NSAIDs
ACEi
CCBs
What is erythema multiforme
target lesions usually on extensor surfaces
erythema multiforme can be caused by drugs, but what is the most common cause
HSV
drug causes of erythema multiforme
sulphonamides (e.g. co-trimoxazole) penicillin phenytoin allopurinol carbamzaepine NSAIDs
What is Steven Johnson Syndrome (SJS)
major variant of erythema multiforme that involves epidermal and mucosal blistering
What % of epidermal blistering is there in SJS
<10% of epidermal detachment
Presentation of SJS
fever & flu-like symptoms
then,
epidermal blistering
mucosal blistering
Drugs causing SJS
allopurinol
sulphonamides
anticonvulsants
NSAIDs
Pathogenesis of SJS
deficiency in enzymes required for drug detoxifications, which then triggers an immune response in the skin
Normally - apoptotic cells are eliminated by phagocytes
SJS - apoptotic rate is increased, so cells accumulate and become necrotic, which triggers an inflammatory response
timeline of SJS
lesions usually occur 2-8 weeks after ingestion of drugs
What is Toxic Epidermal Necrolysis (TENS)
severe form of SJS (along a spectrum) that involves keratinocyte necrosis with epidermal and mucosa detachment
What % of epidermal blistering is there in TENS
> 30%
Presentation of TENS
fever & flu-like symptoms
then,
epidermal blistering
mucosal blistering
dehydration
conjunctivitis
(basically like SJS but more severe)
Drugs causing TENS
allopurinol
sulphonamides
anticonvulsants
NSAIDs
Tx TENS and SJS
removal of offending drug
fluid replacement
temperature maintenance (warm room)
pain relief
what is SJS/TENS overlap
epidermal detachment between 10-30%
What is hypersensitivity vasculitis
A cutaneous small vessel vasculitis caused by a drug
Presentation of hypersensitivity vasculitis
Presents like small vessel vasculitis
Timeline of hypersensitivity vasculitis
7-10 days after administration
Drugs causing hypersensitivity vasculitis
allopurinol amiodarone NSAIDs Thiazides Penicillins Sulphonamides Hydralazine
What is erythroderma
A descriptive term that means a widespread scaly erythematous rash covering >90% of body surface area.
What is erythroderma also known as
exfoliative dermatitis
drugs causing erythroderma
barbituates
gold
quinine
sulphonamides
General causes of erythema nodosum
Strep TB Leprosy Sarcoidosis UC Behcet's syndrome Idiopathic Drugs
Drugs causing erythema nodosum
Sulphonamides
OCP
What is a fixed drug eruption
Well-demarcated round/ovoid plaques that occur at the same sites on exposure to the drug
Common sites for a fixed drug eruption
hands, feet, genitalia
drugs caused a fixed drug eruption
tetracyclines
NSAIDs
quinine
OCP
Drugs causing a drug-induced lichenoid eruption
B blockers
Captopril Thiazides
Furosemide
Drugs causing drug-induced pemphigoid
Furosemide
Penicillamine
Penicillin
Sulphasalazine
Drugs causing drug-induced pemphigus
Penicillamine
Captopril
Penicillin Gold
Drugs causing drug-induced photosensitivity
Quinine
Thiazide
Doxycycline
Appearance of drug-induced lupus
Anular rash on sun exposed areas
Drugs causing drug-induced lupus
Hydralazine Procainamide B blockers Phenytoin Thiazides
Drugs causing drug induced hyperpigmentation
Chlorpromazine
