Drug Reactions

Question 1

Most common cutaneous drug reaction

Answer 1

Exanthematic eruption

Question 2

5 features of exanthematic eruption

Answer 2

Itchy
Widespread
Symmetrical
Erythematous 
Maculopapular

Question 3

Onset of exanthematic eruption

Answer 3

Often 1-2 weeks

hours-days if sensitised

Question 4

Most common causative drugs of exanthematic eruption

Answer 4

Abx: Aminopenicillins, Beta-lactams, sulfonamides, clindamycin, tetracyclines
Allopurinol
Anticonvulsants

Question 5

Most common causative drugs of urticaria

Answer 5

Abx- Penicillins, Cephalosporins, Sulfonamides
Opiate analgesics- Morphine, Codeine
NSAIDs
ACE inhibitors

Question 6

5 features of urticarial drug reaction

Answer 6

Intensely itchy
Circumscribed
Raised
Erythematous, often with central pallor 
Rapid onset

Question 7

2 associations of urticarial drug reaction

Answer 7

Angioedema

Anaphylaxis

Question 8

3 features of angioedema

Answer 8

swelling of the deeper dermis and subcutaneous tissues
Disfiguring if involves face + lips
Life threatening if airway obstruction occurs from laryngeal edema/ tongue swelling.

Question 9

3 mechanisms of urticarial drug reaction

Answer 9

Immune/ IgE mediated: Penicillins/ Cephalosporins
Mast cell activation: Morphine, Codeine, NSAIDs
Bradykinin accumulation: ACE inhibitors

Question 10

Immunoallergic reactions

Answer 10

I: IgE, urticaria, angioedema, anaphylaxis
II: immune-complex mediated, vasculitis, thrombocyticopenic purpura
III: lymphocytic, maculopapular exanthema, photosensitivity
IV: Contact dermatitis, EM-SJS-TEN spectrum

Question 11

6 features of lichenoid drug eruption

Answer 11

Planar
Papular
Pruritic
Purple
Polished
Polygonal/ pigmented

Question 12

Most common causative drugs of Lichenoid drug eruption

Answer 12

Beta-blockers
ACE inhibitors
Methyldopa
Penicillamine
Quinidine
Antimalarials
Thiazide diuretics

Question 13

2 features of exfoliative dermatitis/ erythroderma

Answer 13

diffuse erythema + scaling involving ≥90 percent of body surface area
Systemically unwell with lymphadenopathy + malaise

Question 14

Most common causative drugs of exfoliative dermatitis/ erythroderma

Answer 14

Allopurinol
ACE inhibitors
Abx: Penicillins, Sulfonamides
Anticonvulsants: Carbamazepine, Phenytoin
Barbiturates

Question 15

Tx for exanthematic eruption

Answer 15

Drug withdrawal
Topical potent corticosteroid
Oral antihistamine

Question 16

Tx for urticaria

Answer 16

Antihistamines- Loratadine
Prednisolone PO (severe)

Question 17

Tx for angioedema

Answer 17

Antihistamines + Prednisolone PO (non-anaphylactic)

Adrenaline IM + O2 + Fluids (anaphylactic)

Question 18

Tx for exfoliative dermatitis/ erythroderma

Answer 18

Emolients + wet wraps
Topical steroids (mild)
Oral steroids (severe)

Question 19

Tx for exfoliative dermatitis/ erythroderma

Answer 19

Emollients + wet wraps
Topical steroids (mild)
Oral steroids (severe)

Question 20

Most common causative drugs of SJS/ TEN

Answer 20

Sulfonamides
Allopurinol
NSAIDs
Anti-convulsants

Question 21

Difference between SJS and TEN

Answer 21

SJS: Detachment affects < 10% of body surface
TEN: >30%

Question 22

What is DRESS?

Answer 22

Drug reaction with eosinophilia + systemic symptoms

Question 23

5 features of DRESS

Answer 23

Fever (38 to 40°C)
Malaise
Lymphadenopathy
Skin eruption
2-6 weeks of starting drug

Question 24

Most common causative drugs of DRESS

Answer 24

Antiepileptics: carbamazepine, phenytoin, lamotrigine, oxcarbazepine, + phenobarbital
Allopurinol
Sulfonamides