Effect of formoterol, a long-lasting beta 2-adrenoceptor agonist, against methacholine-induced bronchoconstriction.

1. The effects of a new long-acting inhaled beta 2-adrenoceptor agonist aerosol formoterol (12 micrograms), on FEV1, and on methacholine-induced bronchoconstriction, were compared with those of terbutaline (250 micrograms) and placebo in 12 midly asthmatic subjects. 2. PC20, the concentration of methacholine needed to cause a 20% fall in baseline FEV1, was determined 2 and 5 h after formoterol, terbutaline and placebo on separate days. Baseline PC20 was determined on a different day. 3. Compared with terbutaline and placebo, formoterol hastened recovery from methacholine-induced bronchoconstriction, and significantly increased mean PC20 (by 2.2- and 2.9-fold at 2 and 5 h respectively). 4. Thus, formoterol has a protective effect against methacholine-induced bronchoconstriction which lasts for at least 5 h.