Drug rxns

Question 1

4 main types of drug rxns

Answer 1

exanthematous

fixed drug rxn

drug induced hypersensitivity

epidermal necrolysis

Question 2

immediate vs delayed rxn

Answer 2

immediate- less than one hour like urticaria, angioedema, anaphylaxis

delayed- after one hour but less than 6 usually

Question 3

risk factors for drug rxn

Answer 3

female

prior hx

recurrent exposure

HLA type

EBV infections (more rxn to aminopenicillin), HIV (to sulfonamides)

Question 4

exanthematous drug eruption

Answer 4

most common drug rxn, lmitied to skin - widespread and symmetric beginning on trunk usually

erythematous macules and infiltrated (something deeper) papules

pruritis and mild fever

Question 5

time course for exanthematous

Answer 5

starts over 2 days later, may stop around day 8-11

Question 6

tx for exanthematous

Answer 6

topical steroid

antihistamines

Question 7

fixed drug eruption

Answer 7

formation of solitary/localized erythematous patch or plaque that will recur at same site w/ re exposure to drug

Question 8

common causes of fixed drug

Answer 8

NSAIDS
tetracyclines
metro
sulfonamides

Question 9

fixed drug morpho

Answer 9

often mouth, genitalia, acral areas

sharply demarcated, eryth macules evolve to plaques, can have bullae or erosions

healed are dark brown/violet

Question 10

tx for fixed drug

Answer 10

self resolve days to weeks

non eroded can tx w/ topical steroid

eroded can tx w/ topical abx and dressing

refer if widespread or generalized

Question 11

what to order/suspect w/ rash and facial edema

Answer 11

CBC and LFTs- eosinophilia and atypical lypmphs

elevated AST

suspect drug induced hypersensitivity syndrome (DIHS or DRESS-drug rxn w/ eosinophila and systemic sx)

Question 12

DIHS pres

Answer 12

skin eruption w/ systemic sx and internal organ involvement

macular exanthem, erythematous centrofacial swelling, fever, malaise, lymphadenopathy, other organs like liver

most have eosinophilia

Question 13

timing of DIHS

Answer 13

usually 3 weeks after start of med or increasing dose (exanthematous appears in 7-10 days)

signs and sx persist

Question 14

meds implicated in DIHS

Answer 14

allopurinol
abx- sulfa and penicillin
anticonvulsants (phenytoin)
NSAIDs
abacavir (HIV)

Question 15

approach to DIHS

Answer 15

organ systems? LFTs, BUN, Cr, CBC

which drug?

stop/sub meds

topical steroids and anti H if mild

systemic steroids usually- aorund 3 mos w/ slow taper

Question 16

contast SJS and TEN

Answer 16

less than 10% of body area= SJS, more than 30 is TEN

Question 17

pres of SJS/TEN

Answer 17

extensive necrosis and detachment of epidermis and mucosal surface, very painful

prodrome of fever, headache, myalgias

mortality due to sepsis and respiratory failure

Question 18

common drugs w/ SJS/TEN

Answer 18

sulfas
allopurinol
tetracycline
anticonvulsant
NSAIDs

mnemonic SATAN

Question 19

timeline of SJS/TEN

Answer 19

w/i 8 weeks of drug exposure

Question 20

sites of SJS /TEN

Answer 20

symmetric and distributed on face trunk and proximal extremities, rapid expansion

Question 21

skin findings of SJS/TEN (4)

Answer 21

erythematous irregular shaped dusky red macules, progressive coalescence

mucus membrane involvement is key for this dx

skin can detach in sheets, detaches w/ lateral pressure (nikolsky sign)

atypial target lesions w/ dark center, may blister

Question 22

SJS/TEN complication

Answer 22

corneal damage

fluid electolyte and nutriion problems

bactermia and sepsis

mucous membrane stenosis/scarring

Question 23

tx of SJS/TEN

Answer 23

supportive care and removal of offending drugs

care in burn unit w/ high BSA

Question 24

contrast erythema multiforme w/ SJS

Answer 24

sometimes on spectrum, can also have mucosal involvement

more acral and extremities over trunk

usually HSV rather than drug trigger

erupts after 72 hrs, lasts 2 weeks