EpiPen Basics

An epiPen is a lifesaver. Anaphylactic shock is often a quick and severe allergic reaction to things like insect bites and stings, foods ingredients, penicillin or other allergens. In those affected, the skin shows the most common symptoms: hives, flushing and itchiness. anaphylaxisThe lips, tongue and throat often swell. Swallowing and breathing can become extremely difficult. But the epiPen quickly offsets the body’s potentially fatal IgE-overreaction by delivering an epinephrine dose to the outer side of the thigh. From there the compound reaches two types of receptors in the body, alpha and beta. epinephrineThe alpha receptors are found on cells of blood vessel walls. When in contact with epinephrine, the vessels constrict, raising blood pressure, redirecting blood to vital organs such as the heart and brain. When epinephrine reaches the beta receptors, the heart rate increases and airways relax, preventing potential suffocation.

The epiPen has been made straight-forward to use. All one has to do is:

1) Hold it firmly with the orange tip pointing downward and pull out the blue safety cap.

2) Swing and push the orange tip firmly into mid-outer thigh until one hears a “click.”
3) Hold the epiPen on the thigh for ten seconds.
4) Massage the thigh for an equal amount of time.
A child who weighs up to 20 kg receives a dose of only 0.01 milligrams of epinephrine per kg of body mass, which amounts to 0.20 mg. Older toddlers, teens and adults need a 0.30 mg dose. In Canada, an epiPen costs about $100. The plastic injection system is surely more expensive than the injected fluid’s compounds. The solvent and stabilizing ingredients are simple and also present in small quantities: water(2 ml), salt(6 mg), 1.67 mg of sodium metabisulfite, Na2S2O5 and a very minute amount of HCl to lower the pH to about 4. Interestingly, if one calculates the cost of epinephrine alone, it is equivalent to ($100/0.30 mg)*(1000mg/g)*(28.3 g/ounce)* 16 oz* 1 lb = over $150 million per pound! Double that if you’re paying for the 0.15 mg dose!
Returning to medical issues, how long is it before an epiPen reaches its expiry date? The manufacturers aim for a minimum of 12 months. They don’t recommend using expired products. The findings of a University of Manitoba study confirmed the manufacturers’ recommendations. In 28 pens that were between 1 and 90 months (7.5 years) old, they did see evidence of product-breakdown. Moreover, the spike in epinephrine-levels in the blood provided by fresh pens was much higher than what’s obtained from expired ones. See the contrast between dark circles and the squares in the graph of their data. EpiPens

If we compare the squares to the white circles, which represent the control saline solution and the body’s natural levels of hormone, the other conclusion drawn by the investigators becomes apparent. As long as no discoloration or precipitates are seen through the pen’s clear window,  if nothing else is available, an old pen is still better than nothing at all. 

A persistent medical mystery is why allergic reactions and anaphylaxis are becoming more common in children. Skin allergies specifically the United states have almost doubled between 1998 and 2010.  In Canada, in this century’s first decade, type 1 diabetes, another example of immunological responses gone awry and leading to self-destruction of insulin-producing cells, has increased by 40%.  Are immune systems  being compromised by a common stress-factor in our environment?
Other Sources:

http://www.netdoctor.co.uk/allergy-and-asthma/medicines/epipen.html

http://www.epipen.ca/en/about-epipen/how-to-use-epipen

http://www.csaci.ca/include/files/WAO_Anaphylaxis_Guidelines_2011.pdf

http://www.aacijournal.com/content/pdf/1710-1492-7-S1-S6.pdf

Thanks to our nurse Claude Davilmar whose excellent presentation sparked the creation of this essay.

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