Millions of people use epinephrine to fend off potentially life-threatening anaphylactic reactions because of allergies to medications, foods, insect stings and other triggers. People susceptible to anaphylactic reactions experience swelling, hives, low blood pressure, dilated blood vessels and other symptoms, which, if not treated immediately, can be fatal. The most common treatment is the use of a needle-and-syringe auto injector that delivers epinephrine into the body to relieve the symptoms. In the backcountry, the drug can be exposed to extremely cold temperatures when people ski, climb mountains and backpack during winter.
The maker of a widely used auto injector of epinephrine, EpiPen, recommends replacing the device if it gets frozen. Researchers at the University of Utah School of Medicine and two physicians in Jackson Hole, Wyo., wanted to find out if epinephrine can remain effective even if it freezes.
In a study published in Wilderness and Environmental Medicine, they report that after freezing and thawing vials of epinephrine over a period of seven days–to temperatures as low as 13 below zero Fahrenheit–the solution maintained a concentration within limits considered safe for use in emergency situations.
The study, although small, provides evidence that epinephrine does not degrade after freezing and thawing, the researchers report. This information is beneficial to those who recreate in the backcountry and have the potential for severe allergic reactions.