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PHARM 307 > Adverse Cutaneous Drug Reactions > Flashcards

Adverse Cutaneous Drug Reactions Flashcards

1
Q

What are the five main factors that differentiate drug rashes?

A 
Pathogenesis (immunologic, non-immunologic, idiopathic)
Appearance
Onset
Severity
Prognosis
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2
Q

What is the difference between non-immune mediated and immune-mediated drug eruptions?

A
  • Non-immune mediated do not involve typical immunologic mechanisms
  • Immune-mediated occur through immune pathways (e.g., Type I-IV hypersensitivity) or are associated with immune response
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3
Q

What are six examples of non-immune mediated cutaneous drug reactions? ( + example of causative agent)

A
  • Alopecia (chemotherapy, oral retinoids)
  • Bruising (coumadin, heparin, long-term prednisone)
  • Candidiasis (mucosal and cutaneous - broad spectrum antibiotics, steroids)
  • Phototoxicity (tetracycline, doxycycline, thiazides, furosemide, etc.)
  • Drug-induced skin pigmentation (minocycline, silver)
  • Coumadin-induced skin necrosis (coumadin)
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4
Q

Describe cutaneous phototoxicity drug reactions and their causative agents

A

Sunburn-like reaction after sun exposure without need for immune system involvement

  • Caused by tetracycline, doxycycline, thiazides, furosemide
  • Note: Minocycline rarely causes photosensitivity
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5
Q

Describe drug-induced skin pigmentation and its causative agents

A
  • Drug deposits in skin (silver, minocycline - enters acne scars and gives them a dark colour, amiodarone - grey patches)
  • Induction of melanin pigment (flagellate hyperpigmentation of bleomycin, melasma with oral contraceptives - pigment on cheekc, forehead, chin)
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6
Q

Describe coumadin-induced skin necrosis

A

Rare but serious condition starting at the onset of therapy

  • Anticoagulant protein Cis suppressed at greater rate than procoagulant factors, putting patients at risk of paradoxical thrombotic events
  • Often will start heparin first to avoid this
  • Skin breaks down and dies (often in fatty tissue)
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7
Q

What drugs can cause a flare in psoriasis?

A

Lithium
Beta blockers
Etc.

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8
Q

What is erythema nodosum? What drugs can cause a flare or induction of erythema nodosum?

A

Painful subcutaneous nodules on lower legs and inflammation within fat
- Caused by oral contraceptives and sulfonamides

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9
Q

What are three types of immune-mediated cutaneous drug reactions?

A
  • Type I reaction (IgE mediated)
  • Type III reaction (serum sickness-like reaction)
  • Type IV reaction (T-cell mediated)
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10
Q

Describe Type I reactions and their possible causative agents

A
  • IgE mediated reactions
  • Cause hives, angioedema with individual lesions usually lasting less than 24 hours
  • Termed a “true allergy”
  • Beta-lactams, ASA, penicillin are potential causative agents
  • Angioedema can be associated with ACE inhibitors
  • May need to treat with epinephrine if severe; otherwise diphenydramine is sufficient
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11
Q

Describe a Type III reaction and possible causative agents

How long for onset of the reaction?

A
  • Vasculitis
  • Involves small blood vessels and typically starts 7-21 days after initiation of drug therapy
  • Palpable purpura, usually on lower extremities
  • Beta-lactam antibiotics, thiazides, allopurinol are potential causative agents
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12
Q

Describe a type IV reaction

A
  • Allergic contact dermatitis
  • Lesions are eczematous blisters with itching, leads to inflammation
  • Can also have photoallergic CD which needs light exposure and topical/systemic drug
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13
Q

Describe the mechanism of delayed-type hypersensitivity reactions and the two stages

A
  • Sensitization = Chemicals enter skin –> complex with carrier proteins in skin –> complete allergen –> presented to and primes T cells
  • Elicitation = Second exposure –> Primed memory T cells –> Release cytokines and chemotactic factors
  • Some chemicals may cause elicitation in the primary sensitization (e.g., poison ivy)
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14
Q

What are eight types of idiopathic and/or idiosyncratic drug reactions?

A
  • Hypersensitivity reaction
  • Morbilliform eruption/exanthematous
  • Pustular eruptions
  • Bullous eruptions
  • Fixed drug eruptions
  • Lichenoid eruptions
  • Cutaneous pseudolympoma
  • Drug-induced lupus
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15
Q

Describe hypersensitivity reaction, their symptoms, onset, and typical causative drug agents?

A

Idiosyncratic reaction

  • DRESS = Drug reaction with eosinophilia and systemic symptoms
  • Initially look like morbilliform reactions but can be more severe with systemic symptoms (fever, lymphadenopathy, hepatitis, kidney and CNS dysfunction, eosinophilia)
  • Higher rates of mortality
  • Occur later, up to several months after initiating drug therapy
  • Typical causative agents: Anticonvulsants, allopurinol, sulfonamides, etc.
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16
Q

Describe morbilliform eruptions, their symptoms, onset, and typical causative agents

A

Idiosyncratic reaction (most common)

  • Erythematous macules and papules that are itchy and start on trunk and spread
  • Occur within one week of exposure and resolve within 7-14 days (becomes brownish-red, top layer of skin peels)
  • Causative agents: Beta-lactams, sulfonamides, anti-epileptics, thiazides; some are more common with viral infections = HIV + sulfa; mono + amoxicillin
17
Q

Describe three different types of pustular eruptions and different causative agents

A

Idiosyncratic reaction

  • Acute generalized exanthematous pustulosis (AGEP) = diffuse, erythematous pustules/lesions - often caused by beta-lactams or macrolides
  • Acneiform eruptions from oral steroids
  • Pustular psoriasis from withdrawal of corticosteroids
18
Q

What are the three main types of bullous eruptions

A

Idiosyncratic reaction
- Erythema multiforme (EM) - target lesion on palms and soles, bullseye appearance
- Stevens Johnson Syndrome
- Toxic Epidermal Necrosis
All of these involve skin and mucosa with varying severity

19
Q

What is toxic epidermal necrosis?

A

Large surfaces of skin are rapidly denuded (generalized burn, skin peels in sheets)

  • Mucosal membrane is severely affected
  • High mortality rate
20
Q

What are the typical culprits of bullous eruptions? How are the eruptions treated?

A
  • Anticonvulsants, sulfonamides, NSAIDs, allopurinol, etc.; can also be caused by infections (but if reaction is severe, it likely is a drug)
  • Treat by discontinuing offending agent
  • TEN may benefit from IVIg (not steroids)
  • Mild SJS can be treated with systemic steroids
21
Q

What are fixed drug eruptions? What are their symptoms? What are typical causative agents?

A

Idiosyncratic reaction

  • Uncommon reaction where few lesions occur in fixed sites with each administration of the drug
  • Erythematous or dusky red plaques or ulcerative; may be widespread (generalized FDE); often has strong predilection towards genitals
  • Causative agents include acetaminophen, NSAIDs, sulfa, etc.
  • Likely is a localized Type IV hypersensitivity
22
Q

What are lichenoid eruptions? What are the symptoms and onset? What are common causative agents?

A

Idiosyncratic reaction

  • Resemble lichen planus (pruritic, purple, planar, polygonal papules (5 Ps)) usually affecting distal limbs; fine white scale on top
  • Drug induced lichenoid eruptions are usually located on the trunk and have a more reddish hue
  • Often develops 2 months up to 3 years after drug therapy initiation
  • Common causative agents: Beta-blockers, ACE inhibitors
23
Q

What is cutaneous pseudolymphoma? What typically causes it?

A

Idiosyncratic reaction

  • Stimulation of lymphoma on skin pathology
  • Caused by anticonvulsants
  • Typically has an indolent course (painless, not problematic)
24
Q

What is drug-induced lupus? What are the two types? What are the symptoms of each and the causative agents?

A

Idiosyncratic reaction

  • Systemic lupus = Pains, aches, weight loss, heart and lung involvement, vasculitis; no specific cutaneous findings but may have livedo reticularis (lacy purple rash on legs); caused by hydralazine, isoniazid, minocycline**
  • Subacute cutaneous lupus erythematous (SCLE) = Cutaneous form of lupus with annular, erythematous, scaly eruptions exacerbated by sun (systemic symptoms are rare and mild); caused by thiazide diuretics, terbinafine, NSAIDs, etc.

PHARM 307 (15 decks)

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