Optimal dosing of epinephrine in acute asthma.

The safety and efficacy of 0.1-, 0.3- and 0.5-mg doses of epinephrine hydrochloride in the initial treatment of an acute asthma attack were compared in a double-blind study. Epinephrine hydrochloride 1:1000 was injected subcutaneously in 45 emergency room patients suffering from an acute asthma attack. The patients randomly received 0.1, 0.3 or 0.5 mg of the drug. Arterial blood gases, pulmonary function, blood pressure and heart rate were measured before, and at 10 and 20 minutes after dosing. Bronchodilation, as measured by peak expiratory flow rate, occurred at all doses but was significantly greater (p < 0.05) with the 0.5-mg dose than with the 0.1-mg dose (at 10 and 20 minutes) and the 0.3-mg dose (at 20 minutes). Arterial blood gases, heart rate and blood pressure were not significantly different for the three groups (p > 0.05). The study suggests that a 0.5-mg subcantaneous dose represents optimal epinephrine dosing for the initial therapy of acute asthma.