A comparison of atropine sulfate and metaproterenol sulfate in the emergency treatment of asthma

Twenty-one patients presenting to an emergency room with moderate to severe asthma were entered into the following double-blind, crossover study. First, patients inhaled twice at 30-min intervals either atropine sulfate (AS) (3.2 mg and 3.2 mg; total dose, 6.4 mg) or metaproterenol sulfate (MP) (15 mg and 15 mg; total dose, 30 mg). Then after 80 min (crossover), they inhaled either AS (3.2 mg) or MP (15 mg). FEV₁ was measured before treatment and at 30, 40, 70, 80, 110, and 120 min after the start of the study. FEV₁ from 20 patients who completed the protocol were compared (Student's paired t test), and the values are presented as mean ± SEM. Both groups began with equally severe airways obstruction (AS versus MP: 1.02 ± 0.07 L and 0.92 ± 0.15 L, respectively; p > 0.05). After 120 min, when all had received both medications, FEV₁ had improved significantly and similarly among both groups, indicating that initially they had equivalent bronchodilator capacities. Atropine sulfate produced small but significant changes in FEV₁ at 30 and 70 min, but not at 80 min nor after crossover. In contrast, MP both alone and after crossover significantly improved FEV₁. The difference in improvement among the groups was significant at 80 min and after crossover. Atopine sulfate produced multiple adverse effects in all patients. We conclude that during acute severe asthma, AS (6.4 mg) does not produce clinically significant bronchodilation either alone or in combination with MP.