DRUGS Flashcards
what percentage of adverse drug reactions are cutaenous?
30%
name Type 1 immunologically mediated reactions
- anaphylactic reactions
- urticaria
name type II immunologically mediated reactions
- cytotoxic reactions
- pemphigus and pemphigoid (blictering etc.)
name type III immunologically mediated reactions
- immune complex mediated reactions
- purpura rash
name type IV immunologically mediated reactions
- cell mediated delayed hypersensitivty reactions
- T cell mediated can result in erythema/rash
- not dose dependent
name some non-immunological reactions
- can be does dependant
- eczema
- drug induced alopecia
- phototoxicity etc.
give some risk factors for drug eruptions
- age
- gender
- genetics
- concomitant disease (HIV, EBV, CMV)
- immune factors
what are the most common rash presentations?
- exanthematous, morbilliform, maculopapular (75-95%)
- urticarial
- papulosquamous/pustular/bullous
who should be especially considered when suspecting a cutaneous drug eruption?
patients taking medication who suddenly develops a symmetrical skin eruption
- usually stops when drug is withdrawn
- ability of drugs ability to accumulate/be retained in tissue plays a role
- may cross react with a similar class of drug
name risk factors in drugs that may cause eruptions?
- chemical makeup e.g.
- beta lactam
- NSAIDS
- high molecular weight drugs can cause this
- route of administration
- dose
- half life
what is acute generalised exathematous pustulosis? (AGEP)
- small red or whit epustules
- with pruritus and mildn fever
- over 90% of cases are drug induced
- usually takes 1-3 weeks for rash to develop, shorter if sensitised already
what should be done if suspected acute generalised exanthematous pustulosis?
- culture blood and take skin biopsy
- stop causative drug (most often antibacterial)
- prescribe an emollient
what type of hypersensitivity is AGEP?
type IV T cell mediated delayed type hypersensitivity
- can progress to a life threatening reaction
what can a severe AGEP reaction be indictaed by?
- facial erythema and oedema
- fever above 38.5
- skin pain
- dyspnoea and arthralgia
- blisters etc.
- drugs (e.g. penicillins, erythromycin, streptomycin, allopurinol)
- most often drugs are antibacterial
name the two causes of urticarial drug eruptions?
- IgE meduated hypersensitivity reaction type I
- after rechallenge with drug
- direct release of inflammatory mediators from immediate degranulation of mast cells on exposure (on first exposure)
- more triggered by streotypical drigs e.g. aspirin, opiates, NSAIDS, msucle relaxants, vancomycin
name two types of pustular or bullous drug eruptions
- acneiform (papules and pustules resembling acne)
- acute generalised exanthomatous pustulosis
which drugs can trigger acneiform like rash?
- common with glucocorticoids which triggers steroid acne
- androgens, lithium, isoniazid, phenytoin
which drugs can trigger AGEP?
- use of antibiotics
- calcium channel blockers
- anti-malarials
what causes drug induced bullous pemphigoid?
- ACE inhibitors
- penicillin
- furosemide
what are fixed drug eruptions?
- well demarcated round/ovoid plaques
- red/painful
- found in the hands/genitalia/lips and occasionally oral mucosa
- usually just one big red mark
- can reoccur on the same site on re-expousre to drugs
- usualy muld and one single lesion
- can also present as…
- eczematous lesions
- papules
- vesicles
- urticaria
name the adverse drug reactions that cause life threatening cutaneous reactions with overlapping features caused by drugs such as:
- sulfonamides
- aminopenicillins
- anti-epileptics
- NSAIDs
- allopurinol
some patients may develope more severe underlying problems e.g. AIDS
stevens johnson syndrome AND toxic epidermal necrolysis
what are some severe drug reactions to look out for?
- drug reaction with eosinophilia and systemic symptoms (DRESS)
- Acute generalised exanthomatous pustulosis (AGEP)
- non-immunological skin reaction that is caused by the reaction to sunlight (UVA)
- caused by a drug making the individual more photosensitive
- can also be brought on by SLE (lupus) or immunosuppression
- most will affect the patient through a glass window
phototoxic drug reactions
name the two types of phototoxic drug reactions?
ACUTE
- skin toxicity
- systemic toxicity
- photodegradation
CHRONIC
- pigmentation
- photoaging
- photo carcinogenesis
what investigations can be carried out for cutaneous drug eruptions?
- history ad physical exam
- phototesting
- biopsies
- patch and photopatch tests (for suspected contact dermatitis)
- skin prick (for type 1 reaction for suspected allerguc reactions watch for anaphylaxis)
- skin testing is not indicated for serum sickness reaction type 3 or T cell mediated (can trigger conditions)
management of cutaneous drug eurptions?
- discontinue drug and use alternative
- topical corticosteroids
- anti-histamines (if type 1/symptoms of itch)
- allergy bracelets useful for some drugs
common cutaneous drug eruptions?
