Studies of ipratropium bromide and fenoterol administered by metered-dose inhaler and aerosolized solution

Two double-blind, placebo-controlled studies were performed in patients with chronic, partially reversible airflow limitation to compare ipratropium bromide and fenoterol administered singly with the combination treatment. In the first study, ipratropium bromide, 40 micrograms, or placebo was administered 2 h before fenoterol, 400 micrograms, or placebo, both by metered-dose inhaler. The combined treatment demonstrated significant additive bronchodilatation with an improved forced expiratory volume in 1 s (FEV1) response from 3 to 6 h after fenoterol administration. In the second study, ipratropium bromide, 0.5 mg, fenoterol, 2.0 mg, or placebo was administered by aerosolized solution with a nebulizer. The FEV1 response to the combined treatment, administered at the same time, was significantly greater than for fenoterol (0.5, 0.75, 4 and 6 h) and for ipratropium bromide (0.25-1.5, and 4 h) at various times. There was a disproportionate increase in forced vital capacity (FVC) compared with FEV1 for all treatments, suggesting dilatation and increased stability of small airways. In both studies, no synergistic effect is implied. In summary, additive bronchodilatation may be achieved with combined ipratropium bromide and fenoterol treatment by metered-dose inhaler or aerosolized solution.