The pulmonary and extrapulmonary effects of inhaled beta-agonists in patients with asthma.

The cardiovascular, respiratory, and hypokalemic effects of repeated inhalation of fenoterol, albuterol, and isoproterenol were compared in 12 subjects with stable asthma according to a double-blind, crossover design. Ipratropium bromide served as a control providing bronchodilatation without extrapulmonary effects. Subjects inhaled the beta-agonists on an equal-weight basis (400 micrograms) at 0, 30, 40, and 45 minutes. Measurements of heart rate, blood pressure, total electromechanical systole (measure of inotropic activity), preejection period, QTc interval, plasma potassium levels, and forced expiratory volume in 1 second were made 5 minutes after each dose and again at 60 and 75 minutes. There were no differences in the bronchodilating effect between the beta-agonists. However, both fenoterol and isoproterenol resulted in greater positive inotropic stimulation than did albuterol, and fenoterol caused a greater fall in plasma potassium levels than did the other beta-agonists.

RCT Entities:   Population Interventions Outcomes