Drug Eruptions

Question 1

What are examples of a cutaneous manifestation of type 1 hypersensitivity?

Answer 1

Urticaria
Eczema
Psoriasis

Question 2

What are examples of a cutaneous manifestation of type 2 hypersensitivity?

Answer 2

Pemphigus and pemphigoid

Question 3

What are examples of a cutaneous manifestation of type 3 hypersensitivity?

Answer 3

Purpura, rash

Question 4

What are examples of a cutaneous manifestation of type 4 hypersensitivity?

Answer 4

Erythema, rash

Question 5

Is a drug-induced type 4 hypersensitivity reaction dose-dependent (and what does that mean)?

Answer 5

No - it can’t be helped by taking a smaller dose of the drug causing the reaction

Question 6

What are the different types of clinical presentation of a drug-induced reaction?

Answer 6

Exanthemous/maculopapular
Urticarial
Papulo-squamous/pustular/bullous
Pigmentation
Itch/pain
Photosensitivity

Question 7

When should you consider a drug-induced reaction?

Answer 7

Any patient taking medication who suddenly develops a symmetrical skin eruption
Usually resolves when the drug is withdrawn

Question 8

What are patient risk factors for a drug-induced reaction?

Answer 8

Age - more common in young adults than infants and elderly
Gender - females > males
Concomitant disease (viral infections e.g. HIV, cystic fibrosis)
Immune status
Previous drug reaction or positive skin test

Question 9

What are drug risk factors for a drug-induced reaction?

Answer 9

Drug biochemistry - beta-lactam compounds, NSAIDs, high molecular weight
Route of administration
Dose
Kinetics/half-life

Question 10

What factors should be considered when trying to identify which drug is causing a reaction in a patient on multiple drugs?

Answer 10

Which drug is known to be most likely to cause an eruption
Time interval between exposure and development of skin reaction
History of previous exposure to the same drug

Question 11

What is the most common type of drug reaction?

Answer 11

Exanthematous

Question 12

What are exanethmatous drug reactions?

Answer 12

Type 4 hypersensitivity - delayed
Mild and self-limiting
Idiosyncratic

Question 13

How do exanthematous drug reactions present?

Answer 13

Widespread symmetrically distributed rash
Pruritis is common
Mild fever is common
Mucus membranes usually spared

Question 14

When are exanthematous drug reactions usually onset?

Answer 14

4-21 days after first taking drug

Question 15

What are indicators pf a potentially severe and life-threatening exanthematous drug reaction?

Answer 15

Involvement of mucous membranes and face
Widespread confluent erythema
Fever
Skin pain
Blisters, purpura, necrosis
Lymphadenopathy, arthralgia
Shortness of breath, wheezing

Question 16

What are some drugs associated with exanthematous drug reactions?

Answer 16

Penicillins
NSAIDs
Sulphonamides
Erythromycin
Allopurinol

Question 17

What are urticarial drug reactions?

Answer 17

Usually type 1 hypersensitivity reactions - allergy

Produce urticaria, may be associated with angioedema or anaphylaxis

Question 18

What are the two ways drugs can cause an urticarial reaction?

Answer 18

After re-challenge with drug

Direct release of inflammatory mediators from mast cells on first exposure

Question 19

What are examples of drugs that produce an urticarial reaction after re-challenge with drug?

Answer 19

Beta-lactams

Carbamazepine

Question 20

What are examples of drugs that produce an urticarial reaction due to direct release of inflammatory mediators from mast cells on first exposure

Answer 20

Aspirin
Opiates
NSAIDs
Muscle relaxants
Vancomycin
Quinolones

Question 21

What is the difference between the presentations of acneiform drug reactions and acne?

Answer 21

In drug reactions the skin is not shiny - clue that it is not acne

Question 22

What are examples of drugs that cause acneiform drug reactions?

Answer 22

Glucocorticosteroids

Androgens

Question 23

What is acute generalised exanthematous pustulosis, and what drugs can it be caused by?

Answer 23

Rare pustular drug eruption
Can look like pustular psoriasis
Antibiotics
Calcium channel blockers
Anti-malarials

Question 24

What drugs can cause drug-induced bullous pemphigoid?

Answer 24

ACE-inhibitors
Penicillin
Furosemide

Question 25

What is the presentation of fixed drug eruptions?

Answer 25

Well demarcated round/ovoid plaques Red, painful Hands, genitalia, lips Resolves but leaves persistence pigmentation when drug is stopped Can also present as eczematous lesions, papule, vesicles or urticaria

Question 26

What are drugs associated with fixed drug eruptions?

Answer 26

Tetracycline, doxycycline Paracetamol NSIADs Carbamazepine

Question 27

What are the different severe cutaneous adverse drug reactions?

Answer 27

Stevens-Johnson syndrome Toxic epidermal necrolysis Drug reaction with eosinophilia and systemic symptoms Acute generalised exanthemous pustulosis

Question 28

How do acute phototoxic drug reactions present?

Answer 28

Skin toxicity - photosensitivity Systemic toxicity Photodegredation

Question 29

How do chronic phototoxic drug reactions present?

Answer 29

Pigmentation Photoageing Photocarcinogenesis

Question 30

What is a phototoxic drug reaction?

Answer 30

A non-immunological skin reaction arising an individual exposed to enough photo reactive drug and light of the appropriate wavelength

Question 31

What can increased sensitivity to sunlight be caused by?

Answer 31

Drugs Immunosuppression Lupus

Question 32

What are some patterns of skin phototoxicity?

Answer 32

Immediate prickling with delayed erythema and pigmentation Exaggerated sunburn Exposed telangiectasia Delayed 3-5 days erythema and pigmentation Increased skin fragility

Question 33

What are some drugs associated with phototoxic drug reactions?

Answer 33

``` Antibiotica Thiazodes NSAIDs Amiodarone Antifungals Immunosuppressants ```

Question 34

What are important things to know in a history of a drug reaction?

Answer 34

Detailed description of reaction Timing of onset of symptoms in relation to drug administration Previous exposure to drug When did the drug start, when was it stopped and did stopping affect symptoms Photograph of reaction Why was the drug being taken, underlying illness? Comprehensive drug history

Question 35

What investigations should be done for a drug reaction?

Answer 35

History and examination usually sufficient Phototesting for suspected phototoxic reactions Biopsy Patch and photo-patch tests Skin prick test for specific drugs

Question 36

What is the management for a drug reaction?

Answer 36

``` Discontinue drug if possible Use alternative Topical corticosteroids Anti-histamine if type 1 or symptoms of itch Allergy bracelets ```