Allergy and Anaphylaxis

Question 1

Adrenaline

Answer 1

Sympathomimetic

I- Anaphylaxis, severe croup (nebulised)

P- no precautions (emergency medicine)

Dose: IM 10microg/kg (max 500microg) every 3-5 minutes. Epipen adult >20kg 0.3mg IM, child <20kg 0.15mg IM.
IV infusion 0.1microg/kg/min and titrate
Neb- up to 5mg adrenaline

AE- sympathomimetic: tachycardia, anxiety, tremor, increased RR, increased BP

M- BP, RR, HR, allergic reaction,

C- inject in mid-anterolateral thigh, epipen can go through pants, avoid seams of pants, blue to the sky orange to the thigh, patient should lay down if possible, monitor window and expiry, always carry 2 epipens, store in dark 15-25c, anaphyaxis action plan

CAL- nil

Question 2

Sedating Antihistamines

Answer 2

C- sedating antihistamine

I- Allergic conditions, itch, NV, sedation

D
Chlorphenamine (not available as single ingredient)- in cold and flu night tablets- 2mg od
Dexchlorpheniramine (polarmine)- 2mg qid
Doxylamine- 25-50mg before bed. For Preg NV use 12.5mg bd
Promethazine- oral 25-75mg od or 10-25mg bd-tds (max 100mg/day)

M- resolution of allergic symptoms/nausea/insomnia, anticholinergic AE- dry mouth blurred vision dry eyes constipation cognitive impairment urinary retention (avoid in BPM, close angle glaucoma), CNS excitation (avoid in epilepsy- esp promethazine, lowers seizure threshold), age (avoid <2yo SIDs, avoid elderly- anticholinergic AE)

C- causes drowsiness and increased effects of alcohol, dont drive if effected, causes dry eyes and mouth dizziness constipation, use only when required, isomnia- use for shortest time

Others- Brompheniramine, pheniramine, dimehydrinate, diphenhydramine, alimemazine (trimeprazine), cyclizine, cyproheptadine

Question 3

Less-sedating Antihistamines

Answer 3

C- less sedating antihistamines

I- allergic rhinitis, chronic urticaia

D
Loratadine - 10mg od
Desloratadine- 5mg od
Cetirizine- 10mg od 
Fexofenadine- 180mg od (or 120mg in 1 or 2 doses)

M- resolution of itch/hayfever, elderly- increased risk of sedation and anticholinergic effects, sedation (most likely with cetirizine), anticholinergic- dry eyes blurred vision dizziness constipation urinary retention, LFTs (chronic use), mood/behavioural disturbance

C- take once daily (consider taking at night if it makes you drowsy), can make some people tired do not drive or until you know how the medication effects you, may increase the effects of alcohol, anticholinergic AE- dry eyes, dry mouth, constipation, blurred vision,