Subcutaneous epinephrine vs. nebulized metaproterenol in acute asthma

The efficacy and side effects of subcutaneous epinephrine (E) and aerosolized metaproterenol (M) were compared in acute asthma. Adults randomly received E 0.3 mg sub-Q q20min (max 0.9 mg; n = 20) or M 15 mg in 3.0 ml NaCl 0.9% nebulized over 10 minutes (n = 20) in a double-blind fashion. Vital signs and peak expiratory flow rate (PEFR) were measured every ten minutes for one hour. The two groups were comparable in age, weight, baseline theophylline concentration, PEFR, heart rate, and systolic and diastolic blood pressure. PEFR improved in both groups within ten minutes (p less than 0.01; analysis of variance). There was no difference in PEFR between the groups over the one-hour observation period following treatment. Heart rate decreased following treatment in M patients (p less than 0.05), but remained unchanged in E patients. Systolic blood pressure rose slightly in E patients (p less than 0.01), but remained unchanged in M patients. Subcutaneous E and nebulized M are equally effective as initial therapy in acute asthma.