We evaluated the profile of the bronchodilatory effect of three inhaled β 2 -agonists, 24 µg formoterol, 50 µg salmeterol and 200 µg salbutamol, in patients with stable, moderately severe asthma.Thirty asthmatics (mean±SD age 54±8 yrs; forced expiratory volume in one second (FEV1) 58±12% predicted; reversibility of FEV1 21±8% from baseline) participated in a single-centre, double-blind, randomized, single-dose, cross-over study. FEV1 was obtained in baseline condition and 10, 20, 30, 60 min, and every hour up to 12 h after inhalation of the trial drug. Specific airway conductance (sGaw) was measured at baseline condition and 1, 3, 5, 7, 10, 20, 30, 60 min, and every hour up to 12 h after inhalation.Formoterol produced a mean increase in sGaw (as % of baseline) of 44% after 1 min, maximal (135%) after 2 h, and 56% after 12 h. The mean increase in FEV1 was maximal (27%) after 2h, and 10% after 12 h. After salmeterol, mean increase in sGaw amounted to 16% after 3 min, maximal (111%) after 2-4 h, and 58% after 12 h. The mean increase in FEV1 was maximally 25% after 3h, being 11% after 12 h. After salbutamol, mean increase in sGaw was 44% after 1 min and maximal (100%) after 30 min. The peak increase in FEV1 was 25%.We conclude that formoterol (24 µg) and salmeterol (50 µg) had an equal bronchodilatory capacity, which was similar to that of 200 µg salbutamol and lasted for at least 12 h in patients with asthma. However, formoterol had a more rapid onset of action than salmeterol, equal to that of salbutamol. Eur Respir J., 1996Respir J., , 9, 1684Respir J., -1688 Formoterol and salmeterol are the first two drugs of a new generation of β 2 -agonists with prolonged effect. Both compounds, when administered as an aerosol by a metered-dose inhaler (MDI) or when inhaled as a powder, have the property of retaining a bronchodilatory effect for up to 12 h, which accounts for their use in patients with nocturnal asthma. Moreover, the long duration of action allows for a twice daily treatment frequency, for example, on arising in the morning and on going to bed at night, which could be helpful in promoting patient compliance [1][2][3][4][5][6].In vitro work and noncomparative studies on formoterol and salmeterol have shown evidence that there are small differences between the two inhaled drugs with regard to the speed of onset of a bronchodilatory effect, duration of action and dose-dependency of the duration of effect [6][7][8][9][10][11][12][13]. At the present time, a few comparative studies in patients with chronic obstructive pulmonary disease (COPD) have been published [14,15], however, a direct comparison of the profile of the bronchodilatory effect in asthma is still lacking.The purpose of the present study was to compare the onset and duration of action of 24 µg formoterol, 50 µg salmeterol and 200 µg salbutamol in patients with moderately severe asthma.
Patients and methodsThirty adults with asthma, 8 females and 22 males, who met the American Thoracic Society (ATS) diagnostic criteria for asthma [16], vo...