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 “It’s definitely a small study, but it gives us pretty conclusive
evidence that the freeze-thaw does not seem to degrade the
epinephrine,” said Dr. William Smith, an emergency medicine
physician at St. John’s Medical Center in Jackson Hole, Wyoming, and
one of the study’s authors. “If it does freeze, it’s most likely
going to be okay to administer and help the patient in an emergency
setting.”
Epinephrine is used by people with severe allergies to insect
stings, plants, medications or certain foods, the authors note in
the journal Wilderness and Environmental Medicine. An estimated 1 to
2 percent of the population worldwide has such life-threatening
allergies, they write.
Without the life-saving drug, those people can experience itchiness
and swelling, shortness of breath or even heart attack and death
when exposed to an allergen.
People who know they’re at risk usually carry the epinephrine in
autoinjectors, such as EpiPen, which offer a single-use dose of 0.3
mg of the drug intramuscularly by needle and syringe.
“It’s all the way from people in ski areas to backpackers to
mountain climbers and guides, as well as people carrying with a
history of severe allergic reaction or anaphylaxis and not even
having a medical degree…,” said Smith, also a paramedic and medical
director with the U.S. National Park Service.
In backcountry conditions, Smith and colleagues write, the
medication may be exposed to extreme temperatures. The EpiPen’s
instructions include a recommendation to replace the device if it
has been accidentally refrigerated, but the researchers wanted to
see if the product might still be useful in an emergency.
The study team measured the concentration of epinephrine in the
standard dose from an autoinjector, then froze and thawed the liquid
multiple times over seven days, measuring the epinephrine
concentration after each thaw.
The samples subjected to freezing were brought to minus-25 degrees
celsius (minus-13 degrees Fahrenheit) and then allowed to warm to
room temperature, about 22 degrees C (73 degrees F). These samples
were also compared to doses in sealed glass vials that remained at
room temperature but away from direct sunlight during the same
cycle.
After seven days of freeze-thaw cycles, the experimental samples had
a concentration of 1.041 to 1.106 milligrams of epinephrine per
milliliter of fluid, falling within the 0.90 to 1.15 mg/mL
considered safe by United States Pharmacopeia standards.
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“We would have expected the amount of epinephrine in our samples to
change after multiple freeze-thaw cycles if degradation of the
molecule had been occurring, but actually our results showed that
epinephrine concentration generally went up in a statistically
significant trend,” said the study’s lead author Heather Beasley, a
medical student at the University of Utah School of Medicine, by
email.
The authors said a loss of solution or an error could have led to
the slight increase in epinephrine concentrations in the frozen
samples and more study is needed.
Dr. Venkatesh Ballamkonda, a director in the emergency medicine
department at Mayo Clinic in Minneapolis, Minnesota, called the
experiment intriguing.
“Many times medical literature doesn’t have easy applicability to
real life and here’s one that goes from the basic science arena to
real world applicability very easily all the way down to the child
going to school with a peanut allergy,” Bellamkonda told Reuters
Health.
“If it were your son or my son or daughter, I’d want to know the
epinephrine is still good to use if it sits outside,” he said.
Bellamkonda, who was not involved in the study, also noted that a
larger study should examine epinephrine in autoinjectors and not
just vials to gauge how well the devices protect the medication.
“Certainly it’s not conclusive in any way but I think it highlights
an interesting opportunity for (more) knowledge,” Bellamkonda said.
SOURCE: http://bit.ly/1LtZWks Wilderness and Environmental Medicine,
March 2015.
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