Year 4 - Toxicology > 22 - Skin > Flashcards

22 - Skin Flashcards

(42 cards)

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1
Q

Which drugs are most likely to produce skin reactions?

A

Antibiotics

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2
Q

What are the most common cutaneous drug reactions?

A
  • Maculopapular rash (morbilliform) = 91%
  • Urticaria (hives) = 6%
  • SJS, TENS (toxic epidermal necrolysis)
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3
Q

What determines intensity of irritant contact dermatitis?

A

Dose applied

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4
Q

Does irritant contact dermatitis have an

immunlogic mechanism?

A

No

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5
Q

Sx of irritant contact dermatitis

A
  • Eczematous
  • Pink to red patches or plaques
  • Edema in epidermis (blisters)
  • Itching
  • Lichenification (epidermal thickening)
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6
Q

What type of reaction is allergic contact dermatitis?

A

Delayed (type 4) hypersensitivity reaction

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7
Q

Common drugs that can cause allergic contact dermatitis?

A
  • Bacitracin
  • Neomycin
  • Polymyxin
  • Aminoglycosides
  • Sulfonamides
  • Benzocaine
  • Corticosteroids
  • Vitamin E
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8
Q

What type of reaction is contact urticaria?

A

Type 1 immune reaction (IgE mediated)

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9
Q

Common drugs that can cause contact urticaria?

A
  • Bacitracin
  • ASA
  • Ampicillin
  • Neomycin
  • Phenothiazines
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10
Q

What is photosensitivity?

A
  • Abnormal sensitivity to UV and visible light due to endogenous or exogenous factors
  • Can be phototoxicity or photoallergy
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11
Q

Describe phototoxicity

A
  • Can occur at first exposure

- Systemic or topical administration of medications

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12
Q

Characteristics of acute phototoxicity reactions

A
  • Red skin, blisters w/in minutes to hours after UV light exposure (sunburn)
  • Desquamation, peeling
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13
Q

Characteristics of chronic phototoxicity reactions

A
  • Hyperpigmentation

- Thickening

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14
Q

Drugs that can cause phototoxicity

A
  • Amiodarone
  • Fluoroquinolones
  • Captopril
  • TCAs
  • Fluorouracil
  • Furosemide
  • Naproxen, NSAIDs
  • Phenothiazines
  • Tetracycline
  • Warfarin
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15
Q

What type of reaction is photoallergy?

A
  • True type 4 delayed hypersensitivity reaction

- Requires prior sensitization

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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
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17
Q

Drugs causing photoallergy

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A
  • Antihistamines
  • Barbiturates
  • TCAs
  • Diltiazem
  • Glyburide
  • NSAIDs
  • Phenothiazines
  • Quinidine, quinine
  • Sulfonamides
  • Thiazides
18
Q

_____ is the most common dermatosis induced by systemic drugs

Study These Flashcards
A

Maculopapular eruptions

19
Q

Clinical presentation of maculopapular eruptions

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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?

Study These Flashcards
A

Within first week of therapy

21
Q

Drugs that can cause maculopapular eruptions?

Study These Flashcards
A
  • Ampicillin, amoxicillin
  • Cephalosporins
  • Gentamicin
  • Isoniazid
  • Phenytoin
  • Sulfonamides
  • Thiazides
22
Q

Clinical presentation of urticaria

Study These Flashcards
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

Study These Flashcards
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

Study These Flashcards
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
Year 4 - Toxicology
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