Sustained bronchoprotection, bronchodilatation, and symptom control during regular formoterol use in asthma of moderate or greater severity. The Canadian FO/OD1 Study Group.

BACKGROUND

Recent studies have raised concern that regular inhalation of beta2 -agonists may cause a worsening of asthma control compared with on-demand dosing regimens.

OBJECTIVE

The objective of this study was to compare the effect of twice daily formoterol (Foradil), 4 times daily albuterol, and on-demand albuterol on bronchial hyperresponsiveness (BHR), lung function measurements, symptoms, and other indicators of disease control over 6 months inpatients with asthma of moderate or greater severity receiving concomitant inhaled corticosteroids. We also looked for occurrence of rebound BHR on discontinuation of treatment.

METHODS

This was a multicenter, parallel-group, double-blind, clinical trial. Methacholine PC20 was the primary outcome variable. Other outcome variables included symptom scores, use of rescue medication, morning peak expiratory flow (PEF), serial FEV1 measurements, and asthma exacerbations.

RESULTS

Of the 271 randomized patients, 217 completed the study. Formoterol was significantly superior to on-demand albuterol with regard to methacholine PC20, FEV1, PEF, symptom scores, and use of rescue medication at each measured time point/interval. Regular albuterol was superior to on-demand albuterol with regard to PC20 and FEV1, but not PEF or various clinical scores. After a small drop in the magnitude of bronchoprotection and bronchodilatation occurring shortly after randomization, there was no evidence of progressive tolerance to either regular treatment for any of the measured variables or of rebound increase in BHR 2 days after the end of treatment. The formoterol group had the lowest number of exacerbation days, as defined by high intake of rescue bronchodilator and/or symptom scores, whereas the number of exacerbations requiring increased corticosteroid coverage was similar in the 3 groups.

CONCLUSION

In patients with asthma of moderate or greater severity receiving inhaled corticosteroids, formoterol taken twice daily resulted in superior bronchoprotection, bronchodilatation, and clinical control compared with on-demand albuterol over 6 months. Four times daily albuterol was superior to on-demand albuterol for only some of the end points. Progressive tolerance and a rebound increase in BHR on discontinuation of beta-agonists were not found