Epinephrine Self-Administration in Anaphylactic Emergencies: Comparison of Commonly Available Autoinjectors
AbstractLife-threatening anaphylactic emergencies are largely unpredictable. Epinephrine is widely accepted as first-line therapy for anaphylaxis, due to its physiological effects in reversing symptoms of anaphylaxis and with studies showing both reductions in morbidity and mortality associated with its administration. Anaphylaxis can prove fatal; therefore, learning how to use an epinephrine autoinjector is crucial for people with allergies and parents of children who have previously suffered from anaphylaxis. Such people must carry an epinephrine autoinjector with them at all times for administration when required. During an anaphylactic emergency, not only is it important that adrenaline is administered into the correct tissue compartment but also that the correct dose of adrenaline is administered to achieve the desired clinical effect. Studies have shown that on average, on device activation, syringe-based autoinjectors (eg, Anapen, Twinject, and Adrenaclick) are only capable of delivering 25.7% of the total 300 µg (77 µg or 0.08 mL of the 0.3 mL) of the dose contained in the device, whereas the EpiPen autoinjector (a cartridge-based device) delivers 74.3% (223 µg or 0.22 mL of the 0.3 mL) of the dose contained in its device. This is due to key fundamental differences between the 2 autoinjectors with the EpiPen employing a cartridge-based mechanism and having adequate needle length for correct intramuscular compartment delivery of epinephrine compared with syringe-based devices. For patients experiencing an anaphylactic emergency, it is vital that a sufficient amount of the life-saving drug is promptly delivered to the correct tissue compartment in minimal time to ensure maximal clinical benefit. Evidence to date has shown that the cartridge-based autoinjector device (ie, EpiPen) rapidly delivers the greatest amount of epinephrine to the correct tissue compartment for use by patients in anaphylactic emergencies.