November 20, 2018
NEW YORK (Reuters Health) - At least one brand of epinephrine autoinjectors appear to work normally after having been frozen for several hours.
Researchers froze 104 EpiPens at -25 C (-13 F) for 24 hours, thawed them, then fired them into marbleized beef to test their performance. The autoinjectors delivered the same volume of drug as unfrozen control devices, according to findings presented November 16 at the American College of Allergy, Asthma and Immunology's annual conference in Seattle, Washington.
"The results of our study suggest that EpiPen devices are robust to freezing at -25 C for 24 hours, which certainly should give reassurance to families who left an EpiPen in a cold car overnight, or whose child had an EpiPen in a backpack in a snowy playground over lunch," senior author Dr. Julie Brown of Seattle Children's Hospital in Washington told Reuters Health by email.
However, Dr. Brown said, "These conclusions should not be applied to other epinephrine auto-injector devices as each device has its own unique design, and the glass syringe characteristics are different."
Dr. Brown and colleagues tested expired pairs of 104 EpiPens that deliver 0.3 mg epinephrine and 104 EpiPen Jrs that deliver 0.15 mg, freezing one in each pair and holding the other as a control. They measured the increase in the mass of the meat and the decrease in the mass of the devices to calculate how much drug was delivered.
Both outcomes were equivalent for the thawed and control devices, respectively, "indicating that frozen-thawed devices fired a similar mass of epinephrine solution compared with paired control devices," the researchers write.
This finding held up after controlling for epinephrine dose and expiration date.
The team then froze a new batch of 104 unfired devices, thawed them and cut them open to examine the effect of freezing on the materials. They reported that the devices remained structurally sound with no signs of cracks in the vials that hold the drug, no broken seals or other damage.
The study encompassed only one freeze, however.
"We wanted to emphasize that we only assessed the impact of one freezing event lasting 24 hours. The effect of more prolonged freezing or multiple freezing events remains unknown," says Alex Cooper, an undergraduate student of biochemistry, biophysics and molecular biology at Whitman College in Walla Walla, Washington, who carried out the bulk of the research as an internship.
The study also did not address whether or not the drug remains effective after freezing. But the researchers cite a review from 2016 concluding that real-world temperature fluctuations, including freezing, may not degrade epinephrine significantly (https://bit.ly/2BmnMjz).
"Current epinephrine autoinjectors are recommended to be stored at room temperature, however, some patients store them in their cars, where they can be subjected to temperature extremes," said Dr. Anil Nanda, a clinical associate professor of allergy and immunology at the University of Texas Southwestern Medical Center in Dallas, who was not involved in the research.
"It is good to have additional data though on the mass amount of medication in epinephrine autoinjectors after exposure to freezing, which is depicted in this study," he told Reuters Health by email.
American College of Allergy, Asthma and Immunology Annual Scientific Meeting 2018.
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