Epinephrine is a lifesaving medication in the treatment of anaphylaxis, and autoinjection is the preferred method of epinephrine administration.

The issue, according to a study in Allergy, Asthma and Clinical Immunology, is that those products are not universally available or affordable.

Researchers from Seattle Children’s Hospital and the University of Washington noted that little is known about the effects on epinephrine when the drug is drawn up in advance and stored as prefilled syringes.

Accordingly, the study team sought to determine the stability and sterility of epinephrine when stored in syringes. To do that, they searched Embase, Medline, and Web of Science in June 2016 for all studies of epinephrine stored in syringes in concentrations between 0.1 and 1 mg/mL that measured epinephrine’s stability and/or sterility over time, regardless of date published or language.

Ultimately, three studies were included. One study tested two concentrations of epinephrine, but only one study tested epinephrine 1 mg/mL, the concentration clinically relevant for intramuscular use during anaphylaxis.

The researchers report that neither this study nor the study testing 0.7-mg/mL epinephrine found significant degradation after 56 and 90 days, respectively. One of the two studies testing epinephrine at a concentration of 0.1 mg/mL found significant degradation by 14 days, however, while the other found no degradation by up to 168 days.

At the same time, two studies tested for bacterial growth, with none detected after 28 and 90 days, respectively, and one study tested for fungal growth, with none detected after 90 days.

“Limited evidence suggests that syringes filled with 1 mg/mL epinephrine are stable and sterile for 90 days,” the study authors conclude. “More research is needed testing the duration of stability and sterility of prefilled syringes with the 1 mg/mL concentration most commonly used in anaphylaxis, testing more extensively in different storage conditions and across a wider range of marketed syringe brands.”

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