3.4.3 Allergic emergencies
In this section:
Adrenaline 1:1000 (1mg/mL) 0.5 mg IM (= 500 micrograms = 0.5 mL of 1:1000) should be given, (give IM unless experienced with IV adrenaline). Further doses can be given at about 5-minute intervals according to the patient's response.
Adrenaline auto-injectors, pre-assembled syringe with a needle suitable for rapid (IM) administration, are available for patients at risk of anaphylaxis.
After initial resuscitation:
Chlorphenamine 10mg injected slowly intravenously or intramuscularly may be given after the adrenaline. In the community, intramuscular injection may be used.
Hydrocortisone injection 200mg injected slowly intravenously or intramuscularly, taking care to avoid inducing further hypotension. Its onset of action is delayed for several hours, but it may prevent further deterioration in severely affected patients. In the community, intramuscular injection may be used.
Specialist hospital prescribing only.
Icatibant acetate 30mg solution for injection in pre-filled syringe (Firazyr®) is used for the symptomatic treatment of acute attacks of HAE in adults (with C1-inhibitor deficiency). Use is contingent upon the continuing availability of the Patient Access Scheme in NHS Scotland.
C1-inhibitor (human) 500units powder and solvent for solution for injection (Cinryze®) is restricted to long-term prophylactic use in HAE patients (adults and adolescents with C1-inhibitor deficiency) who are unresponsive to maximal conventional approaches to managing long-term symptoms and who present repeatedly with recurrent, uncontrolled acute symptoms. Cinryze® therapy is restricted to use by the Immunology Department (prescribing, use, administration and supervision).