Epinephrine and its Use in Anaphylaxis: Current Issues

Keith J. Simons; F. Estelle R. Simons

Disclosures

Curr Opin Allergy Clin Immunol. 2010;10(4):354-361. 

In This Article

Abstract and Introduction

Abstract

Purpose of review Epinephrine is a life-saving medication in the treatment of anaphylaxis, in which it has multiple beneficial pharmacologic effects. Here, we examine the evidence base for its primary role in the treatment of anaphylaxis episodes in community settings.
Recent findings We review the practical pharmacology of epinephrine in anaphylaxis, its intrinsic limitations, and the pros and cons of different routes of administration. We provide a new perspective on the adverse effects of epinephrine, including its cardiac effects. We describe the evidence base for the use of epinephrine in anaphylaxis. We discuss the role of epinephrine auto-injectors for treatment of anaphylaxis in community settings, including identification of patients who need an auto-injector prescription, current use of auto-injectors, and advances in auto-injector design. We list reasons why physicians fail to prescribe epinephrine auto-injectors for patients with anaphylaxis, and reasons why patients fail to self-inject epinephrine in anaphylaxis. We emphasize the primary role of epinephrine in the context of emergency preparedness for anaphylaxis in the community.
Summary Epinephrine is the medication of choice in the first-aid treatment of anaphylaxis in the community. For ethical reasons, it is not possible to conduct randomized, placebo-controlled trials of epinephrine in anaphylaxis; however, continued efforts are needed towards improving the evidence base for epinephrine injection in this potentially fatal disease.

Introduction

Epinephrine is a natural body constituent, comprising approximately 80% of the catecholamines in the human adrenal medulla. During sudden frightening or life-threatening situations, endogenous epinephrine is released from this site and affects sympathomimetically innervated structures all over the body. The heart rate accelerates and the force of cardiac contractions increases. The blood pressure rises. Blood flow is redistributed from the skin and subcutaneous tissue to the skeletal muscles, splanchnic circulation, and brain. The bronchi and pupils dilate. Oxygenation increases, the blood glucose rises, and the body is prepared for 'fight or flight'.[1]

Early in the 20th century, epinephrine (adrenaline) was synthesized for use in humans. Until mid-century, it was used primarily in asthma treatment, in which it has been largely replaced by selective beta-2 adrenergic agonists such as albuterol (salbutamol). Epinephrine remains widely used for treatment of postintubation croup and viral croup, in which it is given by face mask and nebulizer. It is ubiquitously used in surgery, where dilute solutions (e.g. 1 : 100 000) provide hemostasis and/or prolong the duration of action of concomitantly administered local anesthetics.[1]

In the 1960s, after publication of several case series involving people in community settings with anaphylaxis triggered by foods, medications, and stinging insect venoms,[2] syringes prefilled with epinephrine were introduced so that in the absence of a healthcare professional, those without medical training could inject epinephrine readily. In 1980, epinephrine auto-injectors were introduced.

Currently, the World Health Organization (www.who.int) and the World Allergy Organization consider epinephrine to be an essential medication for anaphylaxis treatment.[3]

All anaphylaxis guidelines recommend injection of epinephrine as the first-line medication of choice in anaphylaxis in community settings as well as in healthcare settings.[4–6] Epinephrine in ampule formulations is universally available worldwide, even in low-resource countries.[7] It is widely prescribed for anaphylaxis;[8•,9,10] indeed, in some countries, the increase in epinephrine prescribing is disproportionately higher than the increase in the rate of occurrence of anaphylaxis.[11]

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