Clinical equivalence of salmeterol/fluticasone propionate in combination (50/100 μg twice daily) when administered via a chlorofluorocarbon-free metered dose inhaler or dry powder inhaler to patients with mild-to-moderate asthma

This multi-centre, randomized, double-blind, double-dummy, parallel-group study was designed to investigate the hypothesis of equivalent efficacy and comparable safety of two inhaled presentations of salmeterol/fluticasone propionate combination product (SALM/FP) 50/100 mug administered twice daily to patients with mild-to-moderate asthma for 12 weeks. The delivery systems were a 25/50 mug strength hydrofluoroalkane (HFA) metered-dose inhaler (MDI) and a Diskus(TM) inhaler (50/100 mug strength). A third group received FP 100 mug twice daily via a chlorofluorocarbon MDI (50 mug strength). A total of 497 patients aged 11-79 years with reversible airways obstruction who were symptomatic on inhaled corticosteroid (ICS) therapy and had room for improvement in lung function were randomized to treatment in a double-blind, parallel-group design (SALM/FP MDI: n=165; SALM/FP Diskus(TM): n=167; FP MDI: n=165) for 12 weeks. A total of 383 patients completed the study according to the protocol. According to the primary efficacy variable, increase in mean morning PEF over weeks 1-12, the two inhaled presentations of SALM/FP were clinically equivalent (adjusted mean increases 43 and 46 l min(-1); treatment difference 3 l min(-1); 95% confidence interval: -6 to 11 l min(-1)). Equivalence was also demonstrated by all secondary efficacy measures. The SALM/FP MDI was significantly superior to the FP MDI for increase in mean morning PEF (treatment difference 19 l min(-1); P < 0.001) and for all secondary measures except FEV1 and symptom-free nights. There was no significant difference between the groups with respect to adverse events and serum cortisol levels. These results demonstrate that the SALM/FP 25/50 <mu>g HFA MDI (two inhalations twice daily) is clinically equivalent to the SALM/FP 50/100 mug Diskus(TM) (one inhalation twice daily). Patients switching to SALM/FP from other MDI-based asthma treatments may now do so without a change of delivery device.