Bronchodilatory effect of subcutaneous epinephrine in acute asthma

Thirty-two adult patients presenting to the emergency department for treatment of acute asthmatic attacks refractory to home medications were studied. Each patient was randomly given a subcutaneous injections of 0.1 mg, 0.3 mg, or 0.5 mg epinephrine in a double-blind fashion. Bronchondilatation, as measured by peak expiratory flow rate (PEFR), was measured before and at 10, 20, and 40 minutes after injection. Bronchondilatation occurred with all dosages of epinephrine. No significant difference in PEFR was demonstrated among the three doses of epinephrine. Mean PEFR at each time differed significantly from the means of the other three values, with a steady increase over time (0.01 less than p less than 0.05). Repeating subcutaneous doses of epinephrine before maximal bronchondilatation is obtained may be irrational and potentially dangerous.