WINNIPEG, MANITOBA-- Wasp stings, peanuts, or latex rubber can be deadly for some allergic children and adolescents. A delay of only moments can prove fatal if the anaphylactic reaction is not counteracted quickly by administration of epinephrine.

But many active, otherwise healthy children are reluctant to carry injectable epinephrine when they go out to play, and thus investigators have sought alternative ways of giving epinephrine for anaphylaxis. In a recent study from the University of Manitoba, metered-dose epinephrine inhalations were tested, but the results proved disappointing.[1] The large number of inhalations needed to achieve the plasma epinephrine concentration attained through injection caused adverse reactions in many patients, ranging from a "yucky" taste to shaking and intermittent muscle twitching, the study's authors concluded.

"Do not depend on an epinephrine metered-dose inhaler for the first aid treatment of anaphylaxis," stressed F. Estelle R. Simons, MD. "A few puffs of epinephrine inhaled from a metered-dose inhaler might give some relief of upper and lower airway obstruction É; however, the amount of epinephrine absorbed into the body as a whole after inhalation is not enough to turn off the anaphylactic reaction and restore the blood pressure to normal. This is true even when the children are coached to take a full dose [of] 10 to 20 puffs," she added.

Dr. Simons and her colleagues had hypothesized that, with expert supervision, children could achieve a prompt and significant increase in plasma epinephrine concentrations through inhalation. This would avoid the pain of injection and might prove to be safer and more cost-effective.

The researchers studied 19 asymptomatic children with a history of anaphylaxis, each of whom was asked to attempt 10, 15, or 20 epinephrine or placebo inhalations (the number of inhalations was based upon the child's weight). Each child was between the ages of 6 and 14 years, had a history of severe allergies and anaphylaxis, and usually carried injectable epinephrine around the clock. Most of the children (nine of the 11 in the epinephrine group and six of the eight in the placebo group) also had a history of asthma, and thus they were accustomed to using a metered-dose inhaler.

Although all the children completed the study, only two in each group were able to take all the inhalations theoretically required to achieve a significantly elevated plasma epinephrine concentration. Among the children given epinephrine, the mean number of inhalations taken was 11. The mean dose inhaled (2.64 mg) was 10-fold higher than the maximum epinephrine dose recommended for injection. Plasma epinephrine concentrations, however, were not significantly raised from baseline or from endogenous levels.

Several children experienced coughing and dizziness. One child, who almost completed the inhalations, achieved a fairly high plasma epinephrine concentration but experienced apprehension, nausea, pallor, shaking, and intermittent muscle twitching. Almost all the children who were given epinephrine complained about the taste of the inhalations.

"Some patients ask if an epinephrine tablet or capsule is available. Unfortunately, though noninvasive and user-friendly, this route of administration is not practical as the epinephrine is inactivated when swallowed," said Dr. Simons, Bruce Chown Professor and Head of the Section of Allergy and Clinical Immunology of the University of Manitoba in Winnepeg. Therefore, until a better means of treatment can be established, recess for some children will still include injectable epinephrine.

--Martha L. Heckel

Reference
1. Simons FER, Gu X, Johnston LM, Simons, KJ. Can epinephrine inhalations be substituted for epinephrine injection in children at risk for systemic anaphylaxis? Pediatrics. 2000;106:1040-1044.