Drug-Induced Skin Disorders Flashcards
True/false: All dermatological reactions happen very soon after administration.
False. Not all. First exposure, may take weeks
What are some risk factors for derm drug reactions?
- Previous reaction history
- Concurrent illness
- Dosage forms (topical>SQ>IM>PO>IV)
- Genetic factors (HLA-B alleles)
What is the meaning of maculopapular eruptions exanthematous?
“To blossom”
What is the most common cutaneous drug eruption?
Maculopapular eruptions exanthematous
What is the presentation of maculopapular eruptions exanthematous?
“Measles-like”
Where can maculopapular eruptions exanthematous occur?
- Abdomen, trunk, upper extremities
- Symmetrical!
True or false: the mucus membrane is involved in maculopapular eruptions exanthematous.
False
How long does it take for maculopapular eruptions exanthematous to occur?
- 1-2 weeks after Rx (previously unexposed) - delayed T cell hypersensitivity reaction
- 12-24 hours after Rx (previously exposed)
What antibiotics can cause exanthematous drug eruptions?
- Beta-lactam (penicillins, cephalosporins, carbapenems, monobactams)
- Sulfonamides
What aromatic amine anticonvulsants can cause exanthematous drug eruptions?
- Phenytoin
- Carbamazepine
- Lamotrigine
- Phenobarbital
What other drugs can cause exanthematous drug eruptions?
- Allopurinol
- Cardiovascular (furosemide, thiazides, captopril)
When do exanthematous drug eruptions resolve?
Self-limiting, resolve in 1-2 weeks after discontinuing
What are the symptoms of exanthematous drug eruptions?
Minor! Pruritis that can be resolved with antihistamines or topical (not systemic) steroids
What does DRESS stand for?
Drug Reaction with Eosinophilia and Systemic Symptoms
How common is DRESS?
Less common, but more severe
How does DRESS present?
- Drug eruption (face, trunk, extremities) - >50% of body surface area!
- Fever
- Facial edema
- Hematologic abnormalities
- End-organ involvement (hepatic, renal - hepatitis!)
When does DRESS occur?
2-8 weeks after first exposure
What are the most common causes of DRESS?
- Aromatic amine anticonvulsants (phenytoin, lamotrigine, phenobarbital, carbamazepine)
- Allopurinol
- Sulfonamides
- Minocycline
- Vancomycin
- Antituberculosis agents
- NSAIDs
In DRESS, what is the pharmacogenomic risk with abacavir?
- HLA-B*5701
- All patient populations
In DRESS, what is the pharmacogenomic risk with allopurinol?
- HLA-B*5801
- Han Chinese, Thai, Korean
In DRESS, what is the pharmacogenomic risk with carbamazepine?
HLA-B1502
* Han Chinese, Japanese
How is DRESS handled without severe organ involvement?
- Oral antihistamines
- Topical steroids - high potency (betamethasone dipropionate, clobetasol propionate, halobetasol propionate)
How is DRESS handled with severe organ impairment?
- Systemic steroids (prednisone 0.5 to 2 mg/kg/day or equivalent - taper over 3-6 months)
- Cyclosporin
- IV immune globulin (IVIG)
How long does it take for DRESS to resolve?
Resolves in weeks to months after discontinuing
What is the classification of Stevens Johnsons Syndrome (SJS) and Toxic Epidermal Necrosis (TEN)?
Febrile mucocutaneous drug reactions
When do febrile mucocutaneous drug reactions occur?
- 7-21 days after first exposure
- About 2 days with additional exposure
How do febrile mucocutaneous drug reactions present?
- Fever, HA, rhinitis, and malaise can precede mucocutaneous reaction
- Affects face, trunk, and extremities - percent of body surface area determines the classification
- Extensive necrosis and detachment of skin and mucosal surfaces
How is SJS arbitrarily defined?
- Involving at least 2 mucous membranes
- Having up to 10% BSA involved
How is TEN arbitrarily defined?
More severe cutaneous and mucosal manifestations - worse than SJS!
Which drugs can cause SJS and TEN?
- Sulfonamide antibiotics
- Tetracyclines
- Quinolones
- Cephalosporins
- Abacavir (HLA-B*5701)
- Allopurinol (drug most associated; HLA-B*5801)
- Carbamazepine (HLA-B*1502)
- Phenobarbital
- Phenytoin
- Valproic acid
- Lamotrigine
- Oxicam NSAIDs (meloxicam, piroxicam)
True/false: the drug suspected for causing SJS/TEN should be discontinued.
True
What constitutes supportive care for SJS and TEN?
- Burn unit preferred if >20% BSA affected
- Rehydration and prevent infections
What medications can be used to treat SJS and TEN?
- Cyclosporine
- Etanercept
- Corticosteroids
- IV immune globulin (IVIG)
How common is fixed drug eruption?
Less common
When does fixed drug eruption appear?
1-21 days after starting Rx
How does fixed drug eruption present?
- Round or oval lesion
- Can have one lesion or multiple
- Commonly seen in hands, feet, lips, genitalia - occurs in same place but appears faster when rechallenged
- Asymptomatic or may have pain, itch, or burn
Which antibiotics can cause fixed drug eruption?
- Sulfonamides
- Tetracyclines
- Metronidazole
- Beta-lactams
Which anticonvulsant can cause fixed drug eruption?
Carbamazepine
Which OTCs can cause fixed drug eruption?
- APAP
- ASA/NSAIDs
How long will it take for fixed drug eruption to resolve?
Self-limiting, resolves weeks after discontinuing Rx
What are the symptoms of fixed drug eruption?
Minor symptoms! Pruritus that can be treated with H1 antihistamines or topical steroids. Pain that can be treated with analgesics
What is the process of phototoxic eruption?
- Photosensitive medication administered
- UVA exposure
- Medication absorbs radiation
- Inflammatory reaction
- Direct cellular damage
- Sunburn
What is the process of photoallergic eruption?
- Photosensitive medication administered
- UVA exposure
- Photoactivation, creates antigen
- Immune reaction
- Direct cellular damage
- Dermatitis
What is the incidence of phototoxic reactions?
High
What is the incidence of photoallergic reactions?
Low
What is the administration route of phototoxic reactions?
Systemic
What is the administration route of photoallergic reactions?
Usually topical
What is the amount of agent required for photosensitivity with phototoxic reactions?
Large (dose-related)
What is the amount of agent required for photosensitivity with photoallergic reactions?
Small (not dose-related)
What is the onset of reaction after exposure to agent and light in phototoxic reactions?
Minutes to hours
What is the onset of reaction after exposure to agent and light in photoallergic reactions?
24-72 hours
Is more than one exposure to agent required in phototoxic reactions?
No
Is more than one exposure to agent required in photoallergic reactions?
Yes
What is the distribution of phototoxic reactions?
Sun-exposed skin only
What is the distribution of photoallergic reactions?
Sun-exposed skin, may spread to unexposed areas
What are the clinical characteristics of phototoxic reactions?
Exaggerated sunburn
What are the clinical characteristics of photoallergic reactions?
Dermatitis
What drugs are common causes of photosensitivity reactions?
- Antibiotics (FQs, tetracyclines, sulfonamides)
- NSAIDS
- Sunscreens
- Phenothiazines
- Sulfonylureas
- Diuretics
- Amiodarone
How can phototoxic eruptions be managed?
- Minimize sun exposure, wear protective sunscreen
- Symptomatic relief (aloe, analgesics)
How can photoallergic eruptions be managed?
- Minimize sun exposure, wear protective sunscreen
- Topical steroids
What medication can cause hyperpigmentation?
Amiodarone
What are the characteristics of amiodarone hyperpigmentation?
- Blue-gray coloration
- Occurs in sun exposed areas
- Not immediate (average 20 months of treatment, minimal cumulative dose of 160 gm)
- Slow recovery
