Bronchodilator characteristics of nebulized metaproterenol sulfate, isoetharine, and atropine in chronic asthma.

A randomized double-blind comparison of aerosolized META, ISO, ATR, and PI solutions delivered by motorized mist nebulizer was conducted in subjects with known reversible airway obstruction. Vital signs and spirometric parameters were monitored sequentially during each of four 6 hr test periods. Abstention from all medication was required for at least 12 hr before each test period. Baseline percent predicted FEV1 and FEF25-75 among subjects for all test periods were statistically similar. Compared to the other agents tested META treatment (15 mg) resulted in significantly improved global response and higher mean percent increases in FEV1 and FEF25-75 over the entire test period as well as at individual measurement points up to 4 hr for FEV1 and 5 hr for FEF25-75. Peak FEV1 and FEF25-75 values with META treatment were noted at 30 min and persisted above baseline during the entire 6 hr. ATR (2 mg) treatment resulted in later onset of bronchodilatory effect and, as with ISO (125 micrograms), more rapid diminution in measured response. Administration of saline alone resulted in a net 9% increase in FEV1 and 11% in FEF25-75 over the entire test period. Clinically insignificant tremor was noted in 41% of META-treated subjects. Delivery of META by a motorized mist nebulizer provides safe, effective bronchodilation and META is superior to the other agents tested in terms of onset of action, peak reversal of airway obstruction, and duration of effect.