2 - drug eruptions Flashcards
what is drug eruption?
adverse drug reaction to skin, they’re very common and can vary in severity
how does type I drug reaction present?
anaphylactic reactions or urticaria
how does type II drug reactions present?
pemphigus or pemphigoid (autoimmune bullous reactions)
how do type III drug reaction present?
purpura/vasculitis = rare but important to recognise as problems w kidney, eye, heart etc
how does type IV reaction to drug present?
erythema/rash (most common)
are immune drug reactions or non-immune drug reactions dose dependent?
non-immunological drug reactions are dose dependent meaning they could have rection just because too high dose so lowering dose could solve problem
*immune drug reactions can’t be solved by lowering dose because allergy to the drug (doesn’t matter how much of it)
what are risk factors for drug eruptions?
patient risk factors = young adult, females, genetic influence, viral infections, previous drug reaction
drug risk factors = certain chemistry (beta lactam etc), topical route, higher dose
*these things make more likely to get reaction
what are the types of drug reactions?
- exanthematous (extensive red rash) - most common
- urticarial (like nettle sting)
- purpuric & vasculitis (severe)
- pustular or bullous
- fixed drug eruptions (round plaques recurring in same site)
- sever cutaneous adverse drug enlargement (severe examples)
- phototoxic cutaneous reactions
what drugs common to cause reactions?
loads of drugs can cause loads of reactions ( i have specific ones written down) but in general beta lactam antibiotics, anti-epileptics, antimalarials etc
how does exanthematous drug eruptions present?
= type IV reaction
- widespread symmetrically distributed maculopapular rash (red & itchy & bumpy)
- pruritus common
what are indicators for severe exanthematous reaction?
= generally exanthematous reactions are mild & self limiting but a few thing suggest severe:
- involving mucous membrane or face
- facial erythema or oedema
- fever above 38.5
- blisters, purpura, necrosis
- skin pain
- lymphadenopathy/arthralgia
- dyspnoea/wheezing
how does urticarial drug reactions present?
= type I IgE mediated
= associated w angio oedema & anaphylaxis and like hives/nettle rash
what is purpuric vasculitis drug reaction presentation?
= it’s a non-blanching palpable purpura
(indicates severe reactions since inflammation of small vessels in skin then could be happening anywhere like renal vasculitis or eye & heart etc (important for careful drug history)
what are a few types of pustular or bullous drug eruptions?
- acneiform (weightlifters taking steroids)
- acute generalised exanthematous pustulosis (AGEP) = big sheet of pustules
- drug induced bullous pemphigoid
- linear IgA disease
what are fixed drug eruptions?
round oval plaques that come up at same site every time take dose of drug
- red & painful, common on hands & lips , also genitalia or oral mucosa
what are some examples of sever drug reactions?
- stevenson johnson syndrome (SJS) = mucosal ulceration
- drug reaction w eosinophilia & systemic symptoms (DRESS) = widespread erythema & facial oedema
- acute generalised exanthematous pustulosis (AGEP) = sheet of pustules
what are some consequences of severe drug reactions?
- hypothermia
- fluid loss
- protein loss
- sepsis
- multi-organ failure
what is phototoxic cutaneous drug reaction?
= non-immunological reaction from someone who’s been exposed to photo reactive drug (drug that interacts w UV light making free radical release & tissue injury = rash)
what are symptoms associated with phototoxicity?
- immediate prickling w delayed erythema & pigmentation (when in sun)
- exaggerated sunburn
- exposed telangiectasia
- increased skin fragility
what are some additional investigations done if history not sufficient?
- blood tests (eosinophilia supports)
- phototesting for phototoxic drugs
- biopsies to exclude stuff like psoriasis
- patch test for type IV
- skin prick test for type I
what is management of drug eruptions?
- discontinue drug
- topical corticosteroid
- antihistamines help itch
