22 - Skin Flashcards
1
Q
Which drugs are most likely to produce skin reactions?
A
Antibiotics
2
Q
What are the most common cutaneous drug reactions?
A
- Maculopapular rash (morbilliform) = 91%
- Urticaria (hives) = 6%
- SJS, TENS (toxic epidermal necrolysis)
3
Q
What determines intensity of irritant contact dermatitis?
A
Dose applied
4
Q
Does irritant contact dermatitis have an
immunlogic mechanism?
A
No
5
Q
Sx of irritant contact dermatitis
A
- Eczematous
- Pink to red patches or plaques
- Edema in epidermis (blisters)
- Itching
- Lichenification (epidermal thickening)
6
Q
What type of reaction is allergic contact dermatitis?
A
Delayed (type 4) hypersensitivity reaction
7
Q
Common drugs that can cause allergic contact dermatitis?
A
- Bacitracin
- Neomycin
- Polymyxin
- Aminoglycosides
- Sulfonamides
- Benzocaine
- Corticosteroids
- Vitamin E
8
Q
What type of reaction is contact urticaria?
A
Type 1 immune reaction (IgE mediated)
9
Q
Common drugs that can cause contact urticaria?
A
- Bacitracin
- ASA
- Ampicillin
- Neomycin
- Phenothiazines
10
Q
What is photosensitivity?
A
- Abnormal sensitivity to UV and visible light due to endogenous or exogenous factors
- Can be phototoxicity or photoallergy
11
Q
Describe phototoxicity
A
- Can occur at first exposure
- Systemic or topical administration of medications
12
Q
Characteristics of acute phototoxicity reactions
A
- Red skin, blisters w/in minutes to hours after UV light exposure (sunburn)
- Desquamation, peeling
13
Q
Characteristics of chronic phototoxicity reactions
A
- Hyperpigmentation
- Thickening
14
Q
Drugs that can cause phototoxicity
A
- Amiodarone
- Fluoroquinolones
- Captopril
- TCAs
- Fluorouracil
- Furosemide
- Naproxen, NSAIDs
- Phenothiazines
- Tetracycline
- Warfarin
15
Q
What type of reaction is photoallergy?
A
- True type 4 delayed hypersensitivity reaction
- Requires prior sensitization
16
Q
Describe photoallergy
A
- Topical meds (photocontact dermatitis) or systemic meds (systemic photoallergy)
- UV light necessary to convert a potential photosensitizing chemical into a hapten that binds to a tissue Ag => allergic response at subsequent exposures
17
Q
Drugs causing photoallergy
A
- Antihistamines
- Barbiturates
- TCAs
- Diltiazem
- Glyburide
- NSAIDs
- Phenothiazines
- Quinidine, quinine
- Sulfonamides
- Thiazides
18
Q
_____ is the most common dermatosis induced by systemic drugs
A
Maculopapular eruptions
19
Q
Clinical presentation of maculopapular eruptions
A
- Morbilliform, exanthematous, rubellaform eruptions
- Initially appear on trunk and pressure areas and spread to entire body
- Flat or raised erythematous lesions, symmetrically distributed
- Few mm size to confluent large areas
- Pruritic macules and papules
20
Q
When do maculopapular eruptions usually appear?
A
Within first week of therapy
21
Q
Drugs that can cause maculopapular eruptions?
A
- Ampicillin, amoxicillin
- Cephalosporins
- Gentamicin
- Isoniazid
- Phenytoin
- Sulfonamides
- Thiazides
22
Q
Clinical presentation of urticaria
A
- Pink or red, edematous, raised papules and plaques
- Localized vasodilation and transudation of fluid from small cutaneous blood vessels
- Angioedema
23
Q
Mechanisms of urticaria
A
- Type 1 hypersensitivity reactions
- Type 3 immune reactions
- Direct effects on mast cells (opioids)
- Inhibition of prostaglandins (ASA, NSAIDs)
24
Q
Drugs associated w/ urticaria
A
- ASA, NSAIDs
- Gold
- Heparin
- Opioids
- Penicillins, sulfonamides
25
Describe fixed-drug eruptions
- Lesions occur at same sites on repeated administration of the drug
- Red, oval or circular patch w/ central pigmentation and/or blistering, asymptomatic or w/ burning
- Face, hands, feet, mouth
- Healing occurs 7-10 days following discontinuation
26
Drugs causing fixed-drug eruptions
- Acetaminophen
- ASA
- Allopurinol
- Barbiturates
- Penicillins
- Sulfonamides
- Tetracyclines
27
What type of reaction is erythema multiforme?
Type 3 immune reaction
28
Describe erythema multiforme?
- Erythematous maculae that becomes edematous and popular over time
- Concentric rings of different colours (red from vasodilation, purple from erythrocyte extravasation, white from edema, black from necrosis)
- Common sites = face, hands, libs, mucous membranes
29
Describe Stevens-Johnson syndrome
- Severe variant of erythema multiforme
- Extensive mucosal and conjunctival edema, erosions
- High fever, myalgia, vomiting, diarrhea, and arthralgias
- Skin lesions can be severe w/ areas of denudation
30
Complications of Stevens-Johnson syndrome
- Keratitis
- Conjunctival scarring
- Blindness
- Pneumonia
- Dehydration
- Esophagitis
31
Drugs causing SJS
- Barbiturates
- Carbamazepine
- Ibuprofen
- Penicillins
- Phenylbutazone
- Quinine
- Salicylates
- Sulfonamides
- Sulfonylureas
- Thiazides
32
Describe toxic epidermal necrolysis (TEN)
- Life-threatening (second only to anaphylaxis) -> 30-50% mortality rates (when diffuse sloughing present)
- Rare; medications involved in 80-95% of cases
33
Drugs causing TEN
- Allopurinol
- Barbiturates
- Chloramphenicol
- Ibuprofen
- Indomethacin
- Penicillins
- Quinine
- Sulfonamides
34
Clinical manifestation of TEN
- Prodromal state of malaise, sore throat, headache, myalgia, fever, arthralgia, N/V/D, chest pain, cough
- Acute onset of cutaneous manifestations w/in hours or days
- Macular lesion w/ burning sensation that enlarges over the body, may form large flaccid bullae w/in erythema
- Detachment of epidermis (necrosis)
- Common sites = palms, soles, mouth, throat, nose, trachea, eyelids, conjunctiva, cornea
35
Complications of TEN
- Similar to second degree burns
- Fluid and electrolyte imbalances
- Septicemia
- Pneumonia
- Hepatocellular damage
- GI ulceration
- Nephritis
- Myocardial damage
36
Describe erythema nodosum
Inflammatory reaction of subcutaneous fat (nodules)
37
Drugs causing erythema nodosum
- Amiodarone
- Bromides
- Penicillins
- Salicylates
- Sulfones
- Tetracyclines
38
Drugs causing drug-induced lupus erythematous
- Barbiturates
- Ibuprofen
- Methyldopa
- Penicillamine
- Phenothiazines
- Phenytoin
- Procainamide
- Quinidine
- Trimethoprim
39
What is purpura?
Bleeding into the skin
40
Causes of purpura
- Drugs that interfere w/ platelet aggregation (valproic acid, ASA)
- Drugs that interfere w/ coagulation (warfarin, heparin)
- Cytotoxic drugs
- Direct endothelial damage (bleomycin)
41
What is hyperpigmentation?
Deposit of melanin in dermis or stimulation of melanin production
42
Which drugs can cause hyperpigmentation?
- Amiodarone
- Chloroquine
- Minocycline
- Heavy metals
- Tetracyclines
- Oral contraceptives
