Drug reaction

Question 1

A 70 year old woman is admitted with HTN and cardiac failure. She is commenced on Indapamide. Her admission is complicated by a UTI. She is treated with amoxicillin as she had a previous drug reaction to cotrimoxazole (trimethoprim + sulphamethoxazole). On the third day of amoxicillin treatment she becomes febrile and develops a generalised maculopapular rash. How would you assess and manage her?

Answer 1

Impression
Given the maculpapular rash developed post- amoxicillin administration, am provisionally concerned about an adverse drug reaction to penicillins, in particular a delayed hypersensitivity reaction with cutaneous manifestations. Otherwise, given recent starting of Indapamide could also be an ADR to this medication.

Given fevers and rash, would notably want to rule out systemic infection; urosepsis, meningitis, or systemic drug reaction (anaphylaxis), and other severe cutaneous drug reactions such as SJS and TENS, DRESS.

• rule out AIN secondary to penicillin
• consider staphylococcal scalded-skin syndrome

Goals

• assess and resuscitate patient utilising primary survey
• rule out serious reactions and red flag DDx.
• cease amoxicillin and continue UTI treatment appropriately
• documentation of adverse reaction

Question 2

Drug reaction - Assessment

Answer 2

Assessment

- Ensure HD stability before proceeding, rule out Sepsis and systemic drug reactions.

Question 3

Drug reaction - History

Answer 3

History
- Rash: onset, features, pain, pruritus, % body covered, mucosal involvement (eyes, mouth)
- REDS: fever, chills, facial oedema and SOB/dyspnoea, blistering, skin tenderness, involvement of mucosal surfaces
- HPI: history of drug allergies, what reactions were documented. known allergy to penicillins?
- Medications: drugs commonly implicated in severe cutaneous reactions include (BERNSA)
o antibiotics
o anti-epileptics
o anti-retrovirals
o NSAIDs
o sulphamethoxazole
o allopurinol

Question 4

Drug reaction - Examination

Answer 4

Examination
- General appearance + vitals
- Derm examination
o size, distribution (% coverage of body), shape, border, colour, consistency, temperature, tenderness, blanching, etc
o involvement of mucosal surfaces?
o Nikolsky sign - desquamation when lateral pressure to affected area is applied.

Question 5

Drug reaction - Investigations

Answer 5

Investigations

• not usually required, but if severe
• bloods: FBC (eosinophils increased in severe cutaneous reactions), UEC, CRP/ESR, LFT, cultures to exclude sepsis

later

• patch testing
• punch biopsy to confirm/exclude dangerous causes

Question 6

Drug reactions - Management

Answer 6

Management
Supportive
- cease Amoxicillin
- document ADR on the drug chart and in patient notes as well as discharge summary
- patient education about allergy and to avoid penicillin-containing medications in the future
- ?cease indapamide, consult cardio

Definitive
- topical/oral corticosteroids and anti-histamines
- regular monitoring for escalation/spread
- treat any organ dysfunction
- good wound care, nursing in burns unit if SJS/TENS
- utilise alternative treatment for UTI - could give cephalexin
SJS:
o term + ophthalmology consults
o wound care, burns unit nursing
o systemic corticosteroids