Effects of Treatment with Formoterol on Bronchoprotection against Methacholine

摘要: Abstract PURPOSE: In addition to their bronchodilatory effects, β 2 -agonists protect against bronchoconstriction, such as that caused by methacholine challenge. However, tachyphylaxis this beneficial effect develops after chronic use of -agonists. We studied whether the frequency or dose treatment with a long-acting -agonist (formoterol) affects degree bronchoprotection afforded challenge and compare effects short-acting (terbutaline). PATIENTS AND METHODS: randomized, parallel group, double-blind study at two centers, patients stable asthma mild moderate severity who were treated inhaled corticosteroids formoterol 6 μg twice daily, 24 12 once daily; terbutaline 500 four times placebo. Treatments given dry powder inhaler for period weeks. Of 72 enrolled, 67 completed study. Methacholine was performed calculate provocative 20% fall in forced expiratory volume 1 second baseline (unprotected) an initial 1-week run-in without -agonists, hour first treatment, again 7 14 days treatment. RESULTS: Each active treatments exhibited significant ( P CONCLUSIONS: Tachyphylaxis weeks therapy formoterol, -agonist, all three dosage regimens tested. contrast, bronchodilator maintained during