Epinephrine (adrenaline) in anaphylaxis

Abstract

Epinephrine (adrenaline) is universally recommended as the initial drug of choice for the treatment of anaphylaxis. No other medication has similar life-saving pharmacologic effects in multiple organ systems, including prevention and relief of both upper and lower airway obstruction, and of shock. Failure to inject epinephrine promptly contributes to anaphylaxis fatalities. It is most effective when given immediately after the onset of anaphylaxis symptoms. The initial recommended adult dose is 0.3-0.5 mg, injected intramuscularly in the anterolateral aspect of the mid-thigh. Injected by other routes, epinephrine appears to have a less satisfactory therapeutic window; for example, onset of action is potentially delayed when it is injected subcutaneously, and risk of adverse effects potentially increases when it is injected intravenously. The possibility of randomized, controlled trials of epinephrine in anaphylaxis should be considered. For ethical reasons, these trials will not be placebo-controlled. They might involve comparison of one epinephrine dose versus another, or one route of epinephrine administration versus another. For first-aid treatment of people with anaphylaxis in the community, novel epinephrine formulations are being developed. These include epinephrine autoinjectors that are safer and easier to use, and epinephrine formulations that can be administered through non-invasive routes.