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Dermatology 1 > Drug Reactions > Flashcards

Drug Reactions Flashcards

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Dermatology Board Prep flashcards
1
Q

Epidemiology of drug reactions

A
  • One of most common skin problems in-patient and clinical
  • Simple exanthems (75-95%) and urticarial (5-6%) vast majority
  • Factors of age, female gender, concomitant viral infections (esp HIV and EBV) increase risk
  • Certain drugs associated with certain reaction patterns
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2
Q

Most frequent offenders in drug reactions

A
  • antibiotics
  • anticonvulsants
  • NSAIDS
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3
Q

Pathophysiology of type I reaction

A
  • drug-induced urticarial, angioedema and anaphylaxis
  • preformed IgE antibodies recognize drug-protein complexes -degranulation of mast cells - release of histamine and pro-inflammatory cytokines.
  • usually require previous exposure to offending drug.
  • immediate type reaction, so can occur within minutes**
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4
Q

Pathophysiology of type IV reaction

A
  • morbilliform drug eruptions, fixed drug eruption, DRESS, and AGEP
  • T cells lymphocytes recognize the drug–protein complex - stimulate cytokines - inflammatory reaction on the skin.
  • delayed type reaction, so 5-7 days
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5
Q

What is the MC type of cutaneous drug reaction?

A

Exanthematous/morbilliform reaction

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6
Q

Etiology of exanthematous/morbilliform reaction

A
  • insidious onset, within first 2 weeks of tx to 2 wks after stopping medication
  • systemic involvement low (simple reaction)
  • widespread erythematous macules/papules.
  • begins proximally, then generally and can become confluent
  • pruritus prominent
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7
Q

Which drugs commonly cause exanthematous/morbilliform reactions?

A

Antibiotics, especially penicillins and Trim-Sulfa most common, especially with EBV, CMV, HIV

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8
Q

Tx of exanthematous/morbilliform reactions

A
  • identify offending drug and D/C if possible
  • topical or oral steroids
  • antihistamines to help with pruritus
  • eruption clears within 2 weeks after stopping agent
  • desquamation expected
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9
Q

Define urticaria/angioedema

A 
Pruritic wheals (mid-dermal swelling) and/or angioedema (deeper dermal/subcutaneous swelling, often to face, mucous membranes) 
*Can be associated with anaphylactic rxn with bronchospasm
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10
Q

Pathophysiology of urticaria/angioedema

A
  • Mast cell degranulation - release of histamine and other inflammatory molecules**
  • ASA and NSAIDS most common nonimmunologic - alter prostaglandin metabolism, enhancing mast cell degranulation
  • Immunologic urticaria MC associated with PCN and related (i.e. augmentin)
  • -IgE antibodies formed
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11
Q

Which drugs frequently cause urticaria/angioedema?

A

ACE inhibitors/ARBs and Angioedema- probably normal pharmacologic effect of the drug by increasing tissue kinin levels

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12
Q

Tx of urticaria/angioedema

A
  • Identify and withdraw offending drug
  • Non-sedating H1 blocking agents: need up to 4x allergic rhinitis dosage
  • Additional H2 blocker, leukotriene antagonist, or sedating H1 blocker may be considered
  • Systemic steroids
  • Subcutaneous epi with anaphylaxis
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13
Q

Define fixed drug reaction

A

Recur at the same site with each exposure to medication

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14
Q

Describe appearance of fixed drug reaction

A
  • Solitary, at times multiple, erythematous to violaceous patch or plaque
  • Well defined.
  • Evolves to target lesion, may blister and erode
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15
Q

Body sites of fixed drug reaction

A

Common sites include the lips, genitals, and extremities

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16
Q

Meds that induce fixed drug reaction

A

NSAIDS (esp. naproxen), tetracyclines, sulfonamides/sulfa drugs, salicylates

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17
Q

Describe Acute Generalized Exanthematous Pustulosis (AGEP)

A
  • Acute febrile eruption with leukocytosis
  • Sudden onset, avg. 5 days after med started
  • Non-follicular sterile pustules occurring on a diffuse, edematous erythema
  • Widespread desquamation follows
  • Mucous membranes involved 20%
  • Neutrophilia in 90%
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18
Q

Define DRESS Syndrome

A

drug rash with eosinophilia and systemic symptoms

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19
Q

When does DRESS occur?

A

later in tx course than simple exanthems, more than 2 weeks up to months after med instituted

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20
Q

How do patients present with DRESS?

A

Fever, malaise, and facial edema (esp. periorbitally) with lymphadenopathy**

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21
Q

Describe rash with DRESS

A
  • Early morbilliform eruption (tiny, fine erythematous macules and papules) which may progress to generalized exfoliative dermatitis/erythroderma
  • Mucous membranes can be involved
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22
Q

DRESS labs

A
  • Eosinophilia
  • atypical lymphocytosis
  • elevated LFTs or renal fxn
  • Can also cause pneumonitis and carditis
23
Q

What are MC drugs to cause DRESS?

A
  • anticonvulsants

- sulfonamides

24
Q

Tx of hypersensitivity syndromes (i.e. DRESS)

A
  • Identify the offending drug and D/C immediately**
  • Some pt clear with just discontinuing the med
  • Liver/renal involvement consider systemic steroids
  • Often low dosage required for months
  • Rash and hepatitis may persist for weeks after the drug is discontinued
25
Q

Patient education regarding DRESS

A
  • the individual must be aware their specific drug hypersensitivity and that other drugs of the same class can cross-react.
  • these drugs must never be re-administered.
  • patient should wear a medical alert bracelet.
26
Q

List the conditions considered mucocutaneous blistering disease

A
  1. Erythema multiforme (EM)
  2. Stevens-Johnson Syndrome (SJS)
  3. Toxic Epidermal Necrolysis (TEN)
27
Q

Define erythema multiforme (EM)

A
  • Acute, self-limited, but sometimes recurrent immune-mediated mucocutaneous disease
  • Separated into EM minor and EM major
28
Q

What causes EM?

A
  • 90% of cases of EM are caused by infections, with herpes simplex virus (HSV) the most common
  • Can be drug-induced- barbituates, antibiotics (especially sulfa and penicillins), anticonvulsants, and NSAIDS
29
Q

How does EM present?

A
  • Abrupt onset of skin lesions.
  • May or may not recall symptoms of an infection in the days to weeks prior to their outbreak
  • Target lesion is classic but can be variable**
30
Q

EM minor etiology

A

Self limited dz, young adults, sometimes recurrent, lasting 1-4 weeks

31
Q

EM minor lesion presentation

A
  • Lesions begin as sharply demarcated erythematous macules, becoming raised and edematous. Several cm in diameter
  • Classic target/iris lesion- 3 zones
  • Central dusky purpura (+/-bullous), elevated edematous pale ring, and surrounding macular erythema
  • Lesions mainly to extremities, starting on dorsal hands and feet and moving toward torso.
  • *Not usually symptomatic!
32
Q

Are mucous membranes involved in EM minor?

A

Nope :)

33
Q

Etiology of EM major

A

-Frequently accompanied by febrile prodrome, +/- arthralgia

34
Q

EM major lesion presentation

A

Face and extremities - involves the trunk more than EM minor (papular,erythematous)

35
Q

EM major

A
  • Mucous membrane involvement is prominent***

- Involves oral mucosa but also genital and/or ocular mucosa

36
Q

Tx of EM

A
  • Treat the suspected infectious disease or to discontinue the causal drug
  • Oral antihistamines and topical steroids for symptom relief
  • Coexisting or recent HSV infection, early treatment with oral acyclovir (Zovirax)or suppressive tx for recurrent EM: refer to Derm if this doesn’t control
  • Oral pain- topical “swish and spit” mixtures containing lidocaine, Benadryl
  • Refer to ophthalmology with eye involvement
  • Hospital admission for supportive care, particularly if severe oral involvement restricts drinking
37
Q

Which conditions are considered bullous drug reactions?

A

Stevens-Johnson syndrome (SJS) and Toxic Epidermal Necrolysis (TEN)

38
Q

Define bullous drug reaction

A
  • Acute life-threatening mucocutaneous reactions characterized by extensive necrosis and detachment of the epidermis**
  • Considered to be variants of the same disease spectrum differing in body surface area involved.
39
Q

Epidermal detachment % in SJS

A

< 10%

40
Q

Epidermal detachment % in SJS/TEN overlap

A

10-30%

41
Q

Epidermal detachment % in TEN

A

> 30%

42
Q

Cause of bullous drug reactions

A
  • Idiopathic or drug reaction, drug reaction is primary

- Incidence of approximately 1 to 2 cases per 1 million, frequency higher in older and HIV

43
Q

Drugs that cause SJS/TEN in adults

A

TMP-SMX, nevirapine, lamotrigine, carbamazepine, NSAIDS, allopurinolf

44
Q

Drugs that cause SJS/TEN in children

A

sulfonamides and other antibx, antiepileptics, and acetaminophen

45
Q

Onset of SJS/TEN

A
  • Onset after med exposure from 3 wks to few days

- Prodrome of fever, influenza-like sxs 1-3 days prior to eruption

46
Q

S/sx of SJS/TEN

A

Signs of mucosal irritation (dysphagia, dysuria, and conjunctivitis) are often present for several days before the onset of cutaneous lesions

47
Q

Spread of lesions in SJS/TEN

A
  • Skin lesions appear on face and trunk and rapidly spread – painful skin
  • Lesions are macular erythema followed by desquamation or atypical target lesions with purpuric centers that form bullae, then slough
  • Usually 2 or more mucosal surfaces involved, oral mucosa and conjunctiva most frequent
48
Q

What is + Nikolsky sign?

A
  • skin peels away with laterally applied pressure.

- indicates a separation of the upper epidermis from the lower epidermis

49
Q

Presentation of SJS/TEN

A
  • Sheet-like loss of skin**

- Erythema and painful erosions to mucous membranes: can be severe

50
Q

Dx of SJS/TEN

A
  • skin bx to confirm dx and r/o other mucocutaneous blistering dz
  • preferred site is leading edge of intact blister
51
Q

Tx of SJS/TEN

A
  • Immediate discontinuation of offending med or d/c all unnecessary meds
  • Management is similar to extensive burn- hemodynamic stabilization, caloric replacement, infection prophylaxis, aggressive skin, eye, and mucous membrane care
52
Q

Mortality SJS/TEN

A
  • Sepsis is major cause of death**

- Mortality rate is almost 10% with SJS, 30% for patients with SJS/TEN, almost 50% with TEN.

53
Q

What is MC long term sequelae of SJS/TEN?

A

Referral to ophthalmology with eye involvement

Dermatology 1 (19 decks)

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