Drug Eruptions

Question 1

What are type 1 reactions and what dermatological symptom is an example of this?

Answer 1

Anaphylactic reactions: Urticaria

Question 2

What are type 2 reactions and what dermatological symptom is an example of this?

Answer 2

Cytotoxic reactions: Pemphigus and pemphigoid

Question 3

What are type 3 reactions and what dermatological symptom is an example of this?

Answer 3

Immune complex mediated reactions: purpura/rash

Question 4

What are type 4 reactions and what dermatological symptom is an example of this?

Answer 4

Cell-mediated delayed hypersensitivity reactions: T cell mediated. Erythema/ rash

Question 5

Name some dermatological conditions that are the result of non-immunologically mediated reactions

Answer 5

Eczema, drug-induced alopecia, phototoxicity, skin erosion or atrophy from topically applied 5-fluorouracil or steroids, psoriasis, pigmentation, cheilitis, xerosis

Question 6

What are some risk factors for drugs involved in eruptions?

Answer 6

Chemistry: B-lactam compounds, NSAIDs, high molecular weight/hapten-forming drugs. Route: topical v oral/systemic. Dose, kinetics/half life

Question 7

Describe an exanthematous drug reaction

Answer 7

Most common (90%). Idiosyncratic, T-cell mediated (type IV). Usually mild/self limiting. Widespread symmetrical rash. Mucous membranes spared usually. Pruritus, mild fever common. Onset 4-21 days after first taking drug. Can progress to life-threatening

Question 8

Describe the indicators of a potential severe reaction in exathematous drug eruptions

Answer 8

Involvement of mucous membrane and face.
Facial oedema & erythema.
Widespread confluent erythema.
Fever (>38.5⁰C).
Blisters, purpura, necrosis.
Lymphadenopathy, arthalgia.
Shortness of breath, wheezing.

Question 9

Name some drugs associated with exanthematous drug eruptions

Answer 9

Penicillins
Sulphonamide antibiotics
Erythromycin
Streptomycin
Allopurinol
Anti-epileptics: carbamazepine
NSAIDs
Phenytoin
Chloramphenicol

Question 10

Describe a urticarial drug reaction

Answer 10

Usually type I immediate after rechallenge with drug (B-lactam antibiotics, carbazepine, others++). OR
Direct release of inflamm mediators from mast cells on first exposure (aspirin, opiates, NSAIDs, muscle relaxants, vancomycin, quinolones)

Question 11

Describe possible examples and causes of pustular/bullous drug eruptions

Answer 11

Acne
Glucocorticoids (steroid acne)
Androgens (therapeutic), lithium, isoniazid, phenytoin
Acute generalised exanthematous pustulosis (AGEP)
Rare
Antibiotics, calcium channel blockers, antimalarials

Question 12

What drugs can cause drug induced bullous pemphigoid?

Answer 12

ACEI, penicillin, furosemide

Question 13

What drug can trigger Linear IgA disease?

Answer 13

Vancomycin

Question 14

What are fixed drug eruptions?

Answer 14

Well demarcated round/ovoid plaques. Red/painful. Resolves when drug is stopped, can re-occur on re-exposure. Usually mild. Presents as eczematous lesions, papules, vesicles or urticaria

Question 15

What drugs are associated with fixed drug eruptions?

Answer 15

Tetracycline, doxycycline
Paracetamol
NSAIDS
Carbamazepine

Question 16

Severe cutaneous adverse reactions such as Stevens Johnson syndrome and TEN can be caused by what drugs?

Answer 16

Sulfonamide antibiotics, cephalosporins, carbamazepine, phenytoin, NSAIDs, nevirapine, lamotrigine, sertraline, pantoprazole, tramadol

Question 17

Drug reaction with eosinophilia and systemic symptoms (DRESS) are caused by what drugs?

Answer 17

Sulfonamides, anticonvulsants, allopurinol, minocycline, dapsone, NSAIDs, abacavir, nevirapine, vancomycin

Question 18

What are phototoxic cutaneous drug reactions?

Answer 18

Non-immunological mediated skin reaction which will arise in any individual providing there is enough photo-reactive drug and the appropriate wavelength of light.

Question 19

Describe some major patterns of cutaneous phototoxicity and drugs that can cause these

Answer 19

Immediate prickling with delayed erythema and pigmentation
chlorpromazine, amiodarone
Exaggerated sunburn
quinine, thiazides, DCMT
Exposed telangiectasia
calcium channel antagonists
Delayed 3-5 days erythema and pigmentation
psoralens
Increased skin fragility
nalidixic acid, tetracycline naproxen, amiodarone