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Author:  Australian Allergy CentreSeptember 28, 2015

Anaphylaxis and the Adrenaline Epipen ®

Anaphylaxis

Allergic reactions can be localised or generalised, and range in acuteness from mild to severe. It is not surprising therefore, that not all allergic reactions are treated in the same way. The most appropriate method for treating an allergic reaction is dictated by the severity of an individual’s symptoms(ASCIA, 2015b).

A mild to moderate allergic reaction will include one of more of the following symptoms (ASCIA, 2015b):

– Sneezing, nasal itchiness, runny nose, nasal congestion
– Itching, burning or swelling of the lips, face or eyes
– Abdominal cramps, vomiting, diarrhoea (NB: these are signs of severe allergic reactions to insects)
– Hives, welts, body redness

Mild to moderate allergic reactions are not typically life-threatening. These reactions can usually be effectively remedied with the administration of anti-histamines, and oral or topical steroids. Though not a frequent occurrence, a mild to moderate reaction will sometimes precede a severe allergic reaction (anaphylaxis), so individuals should always be monitored with caution (ASCIA, 2015b).

A severe allergic reaction, more commonly known as anaphylaxis, is a rapid in onset, multisystem, hyper-sensitivity reaction. Anaphylaxis causes potentially life-threatening, cutaneous, respiratory and cardiovascular symptoms and should always be treated as a medical emergency (Frew, 2011). Anaphylaxis is characterised by one or more of the following symptoms (ASCIA, 2015c):

– Difficulty/noisy breathing
– Wheezing, persistent coughing and asthma
– Swelling of the tongue
– Swelling/tightness in the throat
– Difficulty talking and/or hoarse voice
– Hypotension and dizziness or loss of consciousness
– Pale/floppy (young children)

The most common triggers of anaphylaxis include foods, insect stings and medications (ASCIA, 2015b). Milk, eggs, peanuts, tree nuts, sesame, fish, shellfish, wheat and soy, are responsible for approximately 90% of food-related allergic reactions, however any food can initiate anaphylaxis. Bee, wasp and ant stings are the most common causes of anaphylaxis to insect stings. However not all individuals with these allergies will be at risk of anaphylaxis.

Anaphylaxis is a medical emergency which requires immediate treatment and urgent medical attention.  Adrenaline is the drug of choice and first line treatment for anaphylaxis. Adrenaline rapidly reverses the effects of anaphylaxis by reducing throat swelling, opening the airways, and maintaining heart function and blood pressure (ASCIA, 2015c).

 

The Adrenaline Auto-Injector

‘Owing to the unpredictable nature of anaphylaxis, the random occurrence of accidental exposure to allergens, and the short median time to respiratory or cardiac arrest, anaphylaxis is a potentially life-threatening condition and first-aid measures need to be readily available to those affected' (Frew, 2011, p.16).

Adrenaline auto-injectors, such as the Epipen® or Epipen Junior®, are automatic injectors, which contain a single, pre-measured dose of adrenaline. Adrenaline auto-injectors are designed and intended for use by non-medical people in non-medical settings, for the emergency/first aid treatment of potentially life-threatening severe allergic reactions (ASCIA, 2015c).

Adrenaline auto-injectors are typically recommended and prescribed for individuals with a:

– previous history of anaphylaxis
– high risk for anaphylaxis
– diagnosed food allergy with coexisting unstable, or moderate to severe, persistent asthma
– an underlying mast cell disorder(ASCIA, 2015c)

Adrenaline auto-injectors are not normally recommended:

– for individuals with asthma without a history of anaphylaxis or generalised allergic reactions
– for individuals with a positive blood or skin allergy test, without a history of clinical reactivity
– for individuals with a family, rather than individual, history of anaphylaxis or allergy
– for individuals whose food allergy has resolved
– for individuals with local reactions to insect stings
– for individuals who only develop a generalised skin rash to bee or wasp stings
– if the known allergen can be successfully avoided (e.g. drug allergy)
– for individuals with isolated angioedema (ASCIA, 2015c)

Adrenaline auto-injectors in Australia are available in two dosage strengths – 0.15mg and 0.3mg. Which strength auto-injector a doctor prescribes, is determined by the individual's weight. The standard Epipen® auto-injector contains 0.3mg of adrenaline, a dose recommended for adults and children weighing more than 20kg. The Epipen Junior® contains only 0.15mg, a dose appropriate for children weighing between 10 and 20kg (ASCIA, 2015c; Pfizer Canada Inc., 2015). Adrenaline auto-injectors are not usually recommended for infants and children weighing less than 10kg because the risk for fatal anaphylaxis within this age group is very low. The risk for adrenaline overdose is also high in this group – even with the lower dosage 0.15mg adrenaline auto-injectors (ASCIA, 2015c).

Adrenaline auto-injectors should be administered at the first sign of anaphylaxis. That is, upon the demonstration of ONE (or more) symptoms of a severe allergic reaction (see above). Adrenaline inhibits the progression of the anaphylactic response and rapidly reverses the effects of anaphylaxis. Delaying and/or withholding the administration of adrenaline is not recommended, as the risk for serious morbidity (e.g. cerebrovascular damage) and fatalities due to anaphylaxis, is vastly increased (ASCIA, 2015c).

Should an individual develop anaphylaxis at home or in the community, the individual should be laid flat, or if breathing is difficult, allowed to sit. This is important to encourage blood flow to the heart. The adrenaline auto-injector should then be administered firmly into the muscle of the outer, middle thigh. As the administration of additional doses of adrenaline may be necessary it is critical an ambulance (AU, 000) is telephoned immediately, followed by the individual’s emergency contacts/family (ASCIA, 2015b).

When it comes to anaphylaxis, the earlier adrenaline is administered the better an individual’s outcomes. Uncertainty and apprehension about whether or not an individual’s symptoms are caused by anaphylaxis, can lead to delays in administering adrenaline. However, even if there is doubt, the adrenaline auto-injector should be given. It is far more harmful to undertreat anaphylaxis than to over treat a mild allergic reaction with the administration of adrenaline (ASCIA, 2015a; NPS MedicineWise Australia, 2010). For individuals who are both asthmatic and at risk for anaphylaxis, it is recommended the adrenaline auto-injector be given first, followed by asthma reliever medications (ASCIA, 2015a).

NB: Though adrenaline auto-injectors are not intended for the treatment of mild to moderate allergic reactions, mild to moderate allergic reactions can sometimes precede anaphylaxis. It is therefore appropriate high-risk individuals (in particular) be monitored with caution, and adrenaline auto-injectors be located if available. Nevertheless, it is important to recognise not all individuals with allergies are at risk of anaphylaxis.

 

Adrenaline Auto-Injectors and Expiration Dates

Doctors, nurses and pharmacists are commonly asked about the importance of the expiration date on adrenaline auto-injectors, and whether adrenaline auto-injectors can be used to treat anaphylaxis if they are out-of-date.

Adrenaline auto-injectors are not as effective when they have expired, especially if the adrenaline within the injector is visibly discoloured or contains precipitates. Expired adrenaline auto-injectors should therefore not be relied upon for the emergency treatment of anaphylaxis. Individuals at risk for anaphylaxis should always be mindful of replacing their adrenaline auto-injectors prior to their expiration date (ASCIA, 2015).

Nevertheless, for the pre-hospital management of anaphylaxis, it is recommended a recently expired adrenaline auto-injector be used in preference to not administering adrenaline at all (ASCIA, 2015a). This is because the potential benefit of using an expired auto-injector is greater than the potential risk of a suboptimal adrenaline dose or no adrenaline at all (Simons et al., 2010).

 

In Summary:

1. An individual need only demonstrate ONE symptom of a severe allergic reaction (anaphylaxis) to warrant the administration of an adrenaline auto-injector (ASCIA, 2015c).

2. Adrenaline should be administered at the first sign of anaphylaxis. The earlier adrenaline is administered, the better the individual’s outcomes.

3. It is far more harmful to undertreat anaphylaxis than to over treat a mild allergic reaction with the administration of adrenaline. If in doubt, give the adrenaline auto-injector!

4. For individuals with asthma who are at risk for anaphylaxis, the adrenaline auto-injector should be given first, followed by asthma reliever medications (ASCIA, 2015a).

5. In-date adrenaline auto-injectors are most effective for treating anaphylaxis. Using expired adrenaline auto-injectors is not routinely recommended for the emergency treatment of anaphylaxis.

6. Not all individuals with allergies are at risk for developing anaphylaxis (ASCIA, 2015c).

 

 

For more information about adrenaline auto-injectors visit: 

http://www.allergy.org.au/images/pcc/ASCIA_PCC_Adrenaline_autoinjector_FAQs_2015.pdf

http://www.epipen.ca/en/

 

For more information on first aid for anaphylaxis visit:

http://www.allergy.org.au/health-professionals/anaphylaxis-resources/first-aid-for-anaphylaxis

https://www.allergyfacts.org.au/living-with-the-risk/the-basics/management-treatment/in-an-emergency

 

Reference List:

Australasian Society of Clinical Immunology and Allergy [ASCIA]. 2015a. Adrenaline auto injectors: frequently asked questions. Accessed, 8 September, 2015, http://www.allergy.org.au/images/pcc/ASCIA_PCC_Adrenaline_autoinjector_FAQs_2015.pdf

Australasian Society of Clinical Immunology and Allergy [ASCIA]. 2015c. Guidelines for adrenaline autoinjector prescription. Accessed, 3 September, 2015, http://www.allergy.org.au/images/stories/anaphylaxis/2015/ASCIA_Guidelines_AAI_prescription_2015.pdf

Australasian Society of Clinical Immunology and Allergy [ASCIA]. 2015b. First aid treatment for anaphylaxis. Accessed September 10, 2015, http://www.allergy.org.au/images/stories/anaphylaxis/2015/ASCIA_FIRST_AID_FOR_ANAPHYLAXIS_2015.pdf

Frew, A. 2011. What are the ‘ideal’ features of an adrenaline (epinephrine) auto-injector in the treatment of anaphylaxis? Allergy 66, 1, 15-24.

Pfizer Canada Inc. 2015. Epipen® auto-injector. Accessed September 8, 2015, http://www.epipen.ca/en/

NPS MedicineWise Australia. 2010. Adrenaline auto-injector (Anapen) for acute allergic anaphylaxis. NPS Rational Assessment of Drugs and Research, Issue August 2010. Accessed September 7, 2015, http://www.nps.org.au/__data/assets/pdf_file/0010/96499/Anapen.pdf

Simons, R., Gu, X. and Simons, K. 2000. Outdated EpiPen and EpiPen Jr autoinjectors: Past their prime? Journal of Allergy and Clinical Immunology 105, 5, 1025-1030.