Drug allergy and anaphylaxis Flashcards
what are the 2 ways mast cells can be activated in drug allergy reactions?
Via immunoglobulins - IgE
Direct activation - aspirin, contrast media
where can an allergy history be taken from?
patient
carer
GP
community pharmacist
care home
medical notes
summary care record
how do you take a drug allergy history?
all current meds and recent changes including OTC and injections
generic name for drug suspected of causing reaction
exact signs, symptoms and severity of reaction
when reaction occurred
how long before reaction drug was taken
whether the allergy is a first hand recollection
what 5 things should be documented on the drug chart about an allergy?
generic name of drug
relevant non-drug allergies
nature of reaction
signature
Date
what are 5 allergic symptoms?
itch
urticaria
hypotension
angioedema
wheeze
what are 4 rashes that can be caused by non-allergic drug reactions?
morbilliform rash (like measles)
Erythema multiform (urticarial)
fixed drug eruptions
photosensitivity
what 4 antibiotics are betalactams?
penicillins
cephalosporins - cefalexin, cephotaxime
carbapenems - meropenem, impenem
monobactams - aztreonam
what beta-lactam antibiotic is safe in penicillin allergy?
Aztreonam
what beta lactams can be prescribed with caution in those with penicillin allergy?
3rd generation cephalosporins - cefazidime, ceftriaxone
carbapenems - Meropenem - 1% of penicillin allergies have allaergy to carbapenems
How long should a patient be observed for after anaphylaxis?
6-12 hours
what is the dose of adrenaline given to adults and children >12 in anaphylaxis?
500 micrograms IM
0.5ml of 1 in 1000
what are 4 conditions that increase risk of drug allergy?
HIV
EBV
CMV
CF
what medications may patients with chronic urticaria or mastocytosis be sensitive to?
NSAIDs
opioid analgesics
drugs with histamine releaseing properties liek atracurium
what medications are high risk for allergies?
beta lactam antibiotics
neromuscular blocking agents
radiocontrast media
NSAIDs
High molecular weight starches
are women or men more at risk of drug allergies?
women
what are 7 medications that commonly cause allergic reactions?
chlorhexidine
opioids
Antimicrobials
NSAIDs
plasma expanders
muscle relaxants
radiocontrast media
what are 4 ways allergies should be identified in hospital?
red wrist band
documentation on drug chart
documentation in notes
documentation in electronic system
what antihistamine is usually used in mild allergic reactions?
Chlorphenamine
Mild = no evidence of systemic reaction
what is the definition of anaphylaxis?
a serious systemic hypersensitivity reaction that us usually rapid onset and may cause death. Characterised by potentially life threatening compromise in airway breathing or circulation
what scale can be used to assess the severity of allergic reaction?
Sampson severity score
what would be a grade 1 sampson reaction?
localised pruritus, flushing urticaria, angioedema
oral pruritus, tingling or mild lip swelling
what is a grade 3 sampson reaction?
grade 2 skin signs - pruritus, angioedema, urticaria
oral signs + repetitive emesis
rhinorrhoea, congestion, sensation of throat tightness or itch
tachycardia (increase >15 BPM)
change in activity + anxiety
what would be a grade 2 sampson reaction?
generalised pruritus, flushing urticaria, angioedema
grade 1 signs + nausea/vomiting
nasal congestion/sneezing
change in activity leve
what is stage 4 sampson reaction?
skin signs
Oral signs, vomiting + diarrhoea
congestion, throat tightness, barking cough, difficulty swallowing, cyanosis, wheeze, SOB
Dysarrythmia/mild hypotension
light headed, feeling of pending doom
what is a stage 5 sampson score?
skin signs
loss of bowel control
respiratory arrest
severe brady, hypotesion, cardiac arrest
LOC
what is the dose of adrenaline given in children aged 6-12 in anaphylaxis?
300 micrograms
0.3ml 1 in 1000
what is the dose of adrenaline given in children 6 months to 6 years in anaphylaxis?
150 micrograms
0.15ml of 1 in 1000
what is the dose of adrenaline given to children <6 months in anaphylaxis?
100-150 micrograms
0.1-0.15ml of 1 in 1000
when should a second dose of adrenaline be given if needed?
after 5 minutes
what medication can be given to treat skin symptoms of anaphylaxis once patient is stable?
non-sedating antihistamine e.g. certirizine
what is the dose of certirizine for an adult or child over 12?
10mg OD PO
what is the dose or certirizine for a child aged 2-5?
1.5mg BD PO
what is the dose of certirizine for a child aged 6-11?
5mg BD PO
what antihistamine can be given IV or IM?
chlorpheniramine
what other medications can be given in anaphylaxis to help with breathing?
INH or IV salbutamol
ipratropium, amiophylline, magnesium
what are 2 complications of IV adrenaline?
life threatening arrhythmias
hypertension
what is the usual dose of adrenaline in an autoinjector for an adult?
300 micrograms
what is the follow up for a patient after anaphylaxis?
Prednisolone for 3 days
Non-sedating antihistamine for 3 days - as per trust guidelines
Medical allert band
Document allergy
Communicate with GP
warn patient is available over counter
give info leaflet
prescribed 2 adrenaline autoinjectors
report drug reaction via yellow card scheme
when should patient with anaphylaxis be referred to specialist?
all severe reactions - anaphylaxis, SJS
Reactions during or after anaesthesia
when future management may be complicated by unnecessary avoidance of medications
what are the guidelines on use of adrenaline autoinjectors?
carry two at all times
call ambulance after every use
lie down and raise legs after administration
do not leave alone
what are the 3 adrenaline autoinjecters available in the uk?
epipen
emerade
jext
when should mast cell tryptase samples be take?
ASAP after reaction
1-2 hours later - no longer than 4 hours later
At 24 hours
how long should patients be observed for after anaphylaxis?
6-12 hours - adults or >16 years
