View article

In addition to their bronchodilatory effects, β₂-agonists protect against bronchoconstriction, such as that caused by methacholine challenge. However, tachyphylaxis to this beneficial effect develops after chronic use of β₂-agonists. We studied whether the frequency or dose of treatment with a long-acting β₂-agonist (formoterol) affects the degree of bronchoprotection afforded against methacholine challenge and to compare this with the effects of a short-acting β₂-agonist (terbutaline).

In a randomized, parallel group, double-blind study at two centers, patients with stable asthma of mild to moderate severity who were treated with inhaled corticosteroids were treated with formoterol 6 μg twice daily, 24 μg twice daily, 12 μg once daily; terbutaline 500 μg four times daily; or placebo. Treatments were given by dry powder inhaler for a period of 2 weeks. Of the 72 patients who were …