Comparison of the efficacy of formoterol and salmeterol in patients with reversible obstructive airway disease: a multicenter, randomized, open-label trial

Abstract

Background: Beta2-adrenergic agonists are frequently used for the prevention and relief of bronchospasm in patients with reversible obstructive airway disease. Formoterol and salmeterol are long-acting beta2-agonists. In addition to its long duration of action, formoterol has been reported to have an onset of action similar to that of albuterol.

Objective: This study compared the effects on lung function of regular twice-daily inhalation of formoterol or salmeterol in adults with moderate to moderately severe persistent asthma who were receiving daily inhaled corticosteroids.

Methods: In this 6-month, multicenter, open-label, parallel-group study, patients with moderate or moderately severe asthma were randomized to receive either formoterol 12 microg BID or salmeterol 50 microg BID. The primary end point was mean morning peak expiratory flow (PEF) measured 5 minutes after dosing and entered in a patient diary each day during the first 4 weeks of treatment. Secondary end points included mean morning and evening predose PEF and number of episode-free days recorded in the patient diaries during the first 4 weeks of treatment, use and time of rescue medication, symptom scores, and overall mean morning predose PEF (spirometric measurements made by the physician during scheduled visits) for the entire treatment period. Safety assessments included spontaneously reported adverse events and vital signs.

Results: A total of 528 patients were randomized to study treatment, 262 to formoterol and 266 to salmeterol. There were no significant differences in demographic or baseline characteristics between treatment groups, except in the proportion of current smokers in the formoterol group (4.6%) compared with the salmeterol group (1.5%; P = 0.039). Based on the information recorded in patients' diaries, those receiving formoterol showed significant improvement in mean morning PEF measured 5 minutes after dosing (P < 0.001), reduced use of rescue medication (P < 0.03), and an increased number of episode-free days (P < 0.04) compared with patients receiving salmeterol. Mean predose morning and evening PEF and symptom scores based on diary data and mean morning predose PEF based on measurements obtained during office visits were comparable between the 2 treatment groups throughout the study.

Conclusions: In this open-label trial, patients randomized to formoterol treatment had greater improvement in mean PEF 5 minutes after dosing, required significantly less rescue medication (fewer actuations of albuterol), and experienced more episode-free days compared with patients receiving salmeterol. Thus, although both formoterol and salmeterol are long-acting beta2-agonists, formoterol had a more rapid onset of action.