Formoterol fumarate is a new, high-affinity, beta 2-adrenergic receptor agonist that causes bronchodilation for at least 12 h. The purpose of this study was to compare the magnitude and duration of the effect of inhalation of
formoterol (12 and 24 micrograms),
albuterol (200 micrograms), and placebo in terms of protection against
methacholine-induced bronchoconstriction. The 16 stable adult asthmatic subjects were studied on four separate study days. On each study day the subjects inhaled 2 puffs of the study medication, and
methacholine tests were performed at 30 min and 4, 8, and 12 h later. Results were expressed as the provocative concentration of
methacholine required to cause a 20% fall in FEV1 (PC20). At 30 min, 12 and 24 micrograms
formoterol caused a mean 14- to 20-fold decrease in responsiveness, and
albuterol a 12-fold decrease. However,
albuterol had no significant protective effect at 4 h or thereafter, whereas there was still an 8-fold decrease in responsiveness for 24 micrograms
formoterol and a 6-fold decrease for 12 micrograms
formoterol at 12 h. This study has shown that both doses of
formoterol were still actively protective against induced bronchoconstriction 12 h after inhalation, with minimal side effects. This suggests that
formoterol may prove to be a very useful
bronchodilator for the treatment of patients with
asthma who have significant
airway hyperresponsiveness or nocturnal symptoms and who require inhaled beta 2-agonists at least twice daily.