Results may ease concerns for many physicians and patients who live in colder climates.
Recommended storage for epinephrine auto-injectors (EAIs) is near room temperature — between 20-25°C (68-77°F) with permitted excursions between 15-30°C (59-86°F). But for many of the millions of people in the US who carry EAIs for their severe allergies, and especially those in colder climates, ensuring their EAI stays within that small range of temperatures is a big challenge.
But it might not have to be that way. New research presented at the annual meeting of the American College of Asthma, Allergy and Immunology in Seattle, Washington found that even after leaving EAIs in freezing temperatures for a full 24 hours, they still maintain a low risk for malfunction.
“Many people who use EAIs have been concerned about the current shortage of EpiPens,” said allergist Anne Ellis, MD, chair of the ACAAI Anaphylaxis Committee. “It’s important for those who have severe, life threatening reactions to their allergies to have confidence in the EAIs they carry and know they’ll work in an emergency. This study showed that even when an EAI has been unintentionally frozen, the risk is low that it will malfunction.”
To arrive at their results, investigators paired 104 same-lot post-consumer single-common-brand expired EAIs (50 0.3 mg and 50 0.15 mg devices). One of each pair was frozen at -25°C (-13°F) for 24 hours, while the other was kept at recommended temperatures as a control.
After thawing the frozen device, both devices were fired into meat. The increase in meat mass and decrease in device mass were measured to estimate the mass of solution fired.
There was sufficient power (>95%) to conclude equivalence for both outcomes, defined as equivalent if the average difference in mass for frozen devices was within 10% of the difference for unfrozen devices. Two one-sided t-tests showed equivalence for both outcomes (P < .0001), indicating frozen and thawed devices fired a similar mass of epinephrine solution compared with unfrozen devices. Testing continued to show equivalence after controlling for device epinephrine dose (0.3 mg vs 0.15 mg) and expiration date, using two one-sided tests in a general linear model.
“Since many people who live in cold climates use an EAI, we wanted to explore the effects of freezing on how an EAI functions,” said Julie Brown, MD, co-author of the study. “The change in meat weight and device weight was similar between frozen-thawed devices and their controls, indicating that freezing did not affect how the EAIs functioned once they were thawed.”
If a patient has an EAI that was unintentionally frozen and they experience an anaphylactic reaction, it’s better to use a frozen and thawed device than nothing at all, the authors wrote. While the study corroborates evidence from previous reports indicating that frozen EAIs still fire effectively, patients should continue to talk to their allergists to receive a prescription for a newer, never-frozen device if theirs becomes frozen.