Comparison of the robustness and functionality of three adrenaline auto-injectors

Background: Anaphylaxis is a medical emergency that requires the intramuscular injection of adrenaline using an adrenaline auto-injector (AAI). This study compared the robustness and performance characteristics of three AAIs available in Europe. Methods: Three AAIs (Jext ® , EpiPen ® , and Anapen ® ) were tested in terms of the force needed to activate the AAIs, exposed needle length, injection volume, and injection time. Three conditions were used to assess robustness: base conditions, after three successive free-fall drops from 1.5 m, and after a 40 kg static load challenge. The injection depth and estimated volume of solution delivered into ballistic gelatin were also assessed. Results: Less force was required to remove the safety cap from Jext and EpiPen than from Anapen under base conditions. The required force was unaffected by free-fall drop tests, whereas the static load test significantly increased the force required to remove the safety cap from Jext (difference from base value 7.7 N; P < 0.001) and from EpiPen (difference from base value 30.3 N; P < 0.001). Two Anapens could not be activated after the free-fall and static load tests. The mean exposed needle length was 15.36 mm (standard error [SE] 0.04) for Jext, 15.02 mm (SE 0.05) for EpiPen, and 7.49 mm (SE 0.15) for Anapen. The mean maximum injection depth in gelatin within 10 seconds was 28.87 mm (standard deviation [SD] 0.73) for Jext, 29.68 mm (SD 2.08) for EpiPen, and 18.74 mm (SD 1.25) for Anapen. Conclusion: A comparison of the robustness and performance characteristics of the three AAIs showed that cartridge-based devices (Jext and EpiPen) appeared to be significantly more robust and capable of rapidly and consistently delivering the correct dose of adrenaline to the correct tissue compartment than the syringe-based Anapen. Overall, Jext performed better than EpiPen or Anapen following mechanical stress designed to mimic real-world use. Keywords: anaphylaxis, adrenaline auto-injector, Anapen, EpiPen, Jext, injection depth, reliability