6- Drug Eruptions Flashcards
Thought to be important inducers of ADRs
Th1 cells
Most common form of adverse cutaneous drug reaction
Exanthem
Occurs within the first 2 weeks of treatment or even up to 10 days after it has been stopped
Lesions tend to appear proximally esp in groin or axilla
Prominent pruritus
Exanthem (morbiliform or maculopapular reactions)
Most common cause of exanthematous drug eruption
Antibiotics- penicillin TMP SMX
Characteristic features of drug induced hypersensitivity syndrome
Fever
Rash
Internal organ involvement
7 major classes of medications that are implicated in DIHS
ALANA MD Anticonvulsants Long acting sulfonamides Allopurinol Nevirapine Abacavir Minocycline Dapsone
Morbiliform rash with follicular accentuation
Facial edema, fever, internal organ involvement
Rash developing late and lasts for >2 weeks
DIHS/DRESS
Adverse prognosticators in DIHS
Tachycardia Leukocytosis Tachypnea Coagulopathy Thrombocytopenia GI bleeding
Most common anticonvulsant causing DRESS (drug reaction with eosinophilia and systemic symptoms)
Carbamazepine
DRESS begins how many days after intake of anticonvulsant?
30-40 days
After intake of phenytoin etc
Low grade fever pharyngitis
Morbiliform skin eruption with marked facial and neck edema
Begins in trunk and face spreading centrifugally
Elevated LFTs
Anticonvulsant hypersensitivity Syndrome
What drug is considered a safe alternative for px sensitive to aromatic anticonvulsant
Valproate
Usual starting dose for systemic corticosteroid treatment for anticonvulsant hypersensitivity Syndrome
1-1.5 mg/kg/day
Allopurinol hypersensitivity Syndrome usually occurs in patients with
Preexisting renal failure
Minocycline hypersensitivity usually occurs in patients deficient in
Glutathione S-transferase
Morbiliform eruption that heals with desquamation is most characteristic of this drug
Dapsone
The term bullous drug reaction usually refers to a drug reaction in:
A. Erythema multiforme
B. SJS
C. TEN
A
Reactivation of this virus can be seen in SJS/TEN
HHV-6
Most common drug to cause SJS/TEN
TMP-SMX
SJS/TEN in children is most commonly caused by
Sulfonamides
Antiepileptics
Acetaminophen
Most common mucosal surfaces eroded in SJS
Oral mucosa
Conjunctiva
Mucosal involvement usually not found in:
A. SJS
B. TEN
B
Histo:
Lymphocytic infiltrate at dermoepidermal junction with necrosis of keratinocytes
Cellular necrosis out of proportion to the infiltrate
TEN/SJS
Poor prognostic factor in SJS that is not included in SCORTEN
Respiratory involvement
HIV infected patients are at increased risk of developing adverse drig reactions esp if TH cell count is
Between 25 and 200
6 or fewer lesions occur
Recur at the same site with each exposure to medication
Fixed drug eruption
Most common sites affected in fixed drug eruption
Oral and genital mucosa
Begins as red patch that soon evolves to an iris or target lesion similar to EM that may blister and erode
Fixed drug eruption
Lesions in genital and oral mucosa in fixed drug eruption manifest as
Erosions
Pathognomonic of FDE (histo)
Normal stratum corneum
Chronic dermal changes- papillary dermal fibrosis and deep peri vascular pigment incontinence
Drugs that can cause FDE
NSAID- paracetamol naproxen oxicams mefenamic acid (predilection for lips)
Genital- sulfonamides TMP SMX
Risk of developing FDE has been linked to this human leukocyte antigen
HLA B22
Most common culprit of nonpigmented FDE
Pseudoephedrine hydrochloride
Provocation test can be performed to confirm FDE but must be delayed at least _______
2 weeks from last eruption
Oral provocation test should have ___% of the standard dose
10
Patch provocation test should have ___% of the standard dose
10-20
Sudden onset, fever, facial edema
Scarlatiniform — >100 nonfollicular pustules
Mucous membrane involvement common but only affects one surface and is nonerosive
Self limited- 15 days
Acute generalized exanthematous pustulosis (AGEP)
Pustular drug eruption
Frequently associated drugs in AGEP
Ampicillin/ amoxicillin Quinolones Hydroxychloroquine Sulfonamide Terbinafine Imatinib Diltiazem
Histo:
Marked papillary edema
Neutrophil clusters in dermal papillae
Perivascular eosinophils
AGEP
Most common drugs in non immunologic urticaria
Aspirin and NSAIDS
Immunologic urticaria is most often associated with
Penicillin and related B lactam antibiotics
Angioedema is a known complication of the use of
ACE inhibitors and Angiotensin 2 antagonists
Drugs in photosensitive drug reactions
NSAIDs TMP SMX Thiazides Sulfonylureas Quinine quinidine Phenothiazine Tetracycline
