A 4-week comparison of salmeterol and terbutaline in adult asthma*

This was a 4-week, open-label, parallel-group study designed to compare the efficacy and safety of the long-acting inhaled bronchodilator, salmeterol, with the established inhaled bronchodilator, terbutaline, in the treatment of patients with mild to moderate asthma. A total of 243 adult patients was randomized to receive treatment with either salmeterol 50 μg bd via a Diskhaler^TM (Glaxo) inhaler (n=121) or terbutaline 500 μg qds via a reservoir powder inhaler device (n=122). Apart from all bronchodilator treatment which was withdrawn at the start of the run-in period and replaced by inhaled salbutamol to be used as required for symptom relief, all concurrent medications were kept constant throughout the study. Salmeterol produced a significantly greater increase in mean morning peak expiratory flow (PEF) than terbutaline (difference in adjusted means after treatment=28 l/min; 95% CI=19–37 l/min; P<0.001). Likewise, the increase in mean evening PEF was significantly greater following treatment with salmeterol than with terbutaline (difference in adjusted means=9 l/min; 95% CI=0–17 l/min; P=0.045). Salmeterol was associated with a significant reduction in diurnal variation in PEF by comparison with terbutaline (difference in adjusted means=?18 l/min; 95% CI=?24, ?12 l/min; P<0.001). Significant improvements with salmeterol by comparison with terbutaline were also observed in daytime and night-time asthma scores, percentage of symptom-free days and nights, use of additional inhaled bronchodilator, and percentage of days and nights when no additional inhaled bronchodilator was needed. The greater overall improvement in the control of asthma and its symptoms after treatment with salmeterol was further evident from the lower incidence of asthma-related adverse events in patients taking salmeterol compared with those taking terbutaline (2% and 15%, respectively). While both treatments were well tolerated, more patients withdrew from the terbutaline group than from the salmeterol group (12 and 3 patients, respectively) and terbutaline was associated with a higher incidence of drug-related adverse events (26% and 9% in the terbutaline- and salmeterol-treated groups, respectively). This study demonstrated that salmeterol 50 mUg bd via a Diskhaler was significantly more effective and associated with fewer adverse events than terbutaline 500 μg qds via a reservoir powder inhaler device.