Drug Eruptions

Question 1

Are immunologically mediated reactions dose dependent?

Answer 1

No

Question 2

What skin conditions are caused by type 1 hypersensitivity reactions?

Answer 2

urticaria

Question 3

What skin conditions are caused by type 2 hypersensitivity reactions?

Answer 3

pemphigoid and pemphigus

Question 4

How do drug eruptions most commonly present?

Answer 4

exanthematous (rash is a prominent manifestation) is the most common type of drug hypersensitivty reaction. (also known as morbiliform or maculopapular)

Question 5

How else can drug eruptions present?

Answer 5

urticarial in 5-10%
papulosquamous (both papules and scales)
pustular
bullous
pigmentation
itch/pain
photosensitivity

Question 6

When should you consider a drug eruption?

Answer 6

in any patient who is taking medication and develops a symmetric skin eruption of sudden appearance

Question 7

What are the risk factors for the development of drug eruptions?

Answer 7

age- young adults more common than infants or elderly
female gender
concomitant disease- viral infetions or cystic fibrosis
immune status- previous reactions
route

Question 8

What types of drugs are likely to cause eruptions?

Answer 8

B-lactam compounds; NSAIDs
high molecular weight
hapten forming drugs

Question 9

What is a hapten?

Answer 9

Haptens are small molecules that elicit an immune response only when attached to a large carrier such as a protein; the carrier may be one that also does not elicit an immune response by itself.

Question 10

What type of hypersensitivity is involved in exanthematous drug eruptions?

Answer 10

Type 4 (T-cell mediated delayed type)

Question 11

What is the onset of an exanthematous drug eruption after first taking the drug?

Answer 11

4-21 days

Question 12

What would indicate that the exanthematous drug eruption is potentially severe?

Answer 12

involvement of mucous membrane and face
facial oedema and erythema
widespread confluent erythema
fever
blisters, purpura, necrosis
lymphadenopathy, arthralgia
SOB and wheezing

Question 13

What could indicate that the mucous membranes have been involved in the exanthematous drug eruption?

Answer 13

mouth ulcers- dysphagia

difficulty passing urine

Question 14

What are the two ways that an urticarial drug eruption can take place?

Answer 14

Usually- IgE mediated after rechallenge with drug

But- direct release of inflam mediators from mast cells on first exposure–NSAIDs and aspirin

Question 15

What are the 2 types of pustular drug eruption?

Answer 15

acne

acute generalied exanthematous pustulosis (AGEP)

Question 16

What drugs can induce bullous pemphigoid?

Answer 16

ACEIs, penicillin and furosemide

Question 17

What is the characteristic of a fixed drug eruption?

Answer 17

Recurs on the same sites on re-exposure to the drug

Question 18

What is a severe cutaneous adverse reaction?

Answer 18

They combine cutaneous and systemic symptoms

Question 19

Give 4 examples of severe cutaneous adverse reactions

Answer 19

Stevens-Johnson syndrome
Toxic epidermal necrolysis
Drug reaction with eosinophilia and systemic symptoms (DRESS)
Acute generalised exanthematous pustulosis (AGEP)

Question 20

Phototoxic cutaneous drug reactions are immunologically mediated. T/F

Answer 20

False

Question 21

How can phototoxicity present?

Answer 21

exaggerated sunburn
immediate prickling with delayed erythema and pigmentation
exposed telangiectasia
delayed 3-5days erthema and pigmentation
increased skin fragility