Comparison of oral and inhaled metaproterenol for prevention of exercise‐induced asthma

The effectiveness of inhaled versus oral metaproterenol in preventing exercise‐induced asthma (EIA) was studied. Inhaled metaproterenol given 10 min before the exercise significantly reduced the degree of EIA in a group of twenty‐four patients, and in 75% of them completely prevented it. The mean percentage decrease in FEV₁ was 6‐5% with the inhaler and 30.1%, with placebo. When inhaled 1 hr before the exercise, metaproterenol was still better than placebo but its effectiveness was considerably lower. Metaproterenol tablets had a slight protective effect given I hr before, and none when administered 2 hr before exercise. There was no correlation between the protective effect against EIA and the bronchodilating effect obtained before exercise. Metaproterenol administered by metered‐dose inhaler is a very effective prophylactic medication against clinically troublesome EIA, while metaproterenol tablets should not be recommended for this purpose.