Objective: To compare the efficacy and safety of a new combination Diskus inhaler containing both salmeterol 50 mg and fluticasone propionate 250 mg (Seretide) with the two drugs delivered via separate Diskus inhalers.
Design: A multicentre, double-blind, double-dummy study. Three hundred and seventy-one symptomatic asthma patients (age range 13 to 75 years, mean 42 years) receiving inhaled corticosteroids were randomly assigned to two treatment groups: 28 weeks' treatment with either salmeterol/fluticasone propionate (50/250 microg bid) via a single Diskus inhaler (combination) and placebo bid via another Diskus inhaler, or salmeterol 50 microg bid via one Diskus inhaler and fluticasone propionate 250 microg bid via another (concurrent). Morning peak expiratory flow rate (PEFR) and symptoms were measured for the first 12 weeks and safety data were collected throughout the study.
Results: Over weeks 1 to 12, adjusted mean improvements in morning PEFR were 43 and 36 L/min for combination and concurrent therapies, respectively. The difference between the two treatment arms was 6 L/min (90% CI -13 to 0 L/min; P=0.114), which was within the predefined criteria for clinical equivalence. Adjusted mean improvements in forced expiratory volume in 1 s from baseline for week 28 were also similar between the two therapies. Thirty-five per cent of patients receiving combination inhaler and 31% of those receiving concurrent therapy had a mean daytime symptom score of zero over weeks 1 to 12 compared with 1% and 2%, respectively, at baseline. There was no difference in the incidence of adverse events between the two treatment arms. Mean serum cortisol levels were similar, and no differences in frequency of abnormal results were noted between the two groups.
Conclusions: This study shows that the combination of salmeterol and fluticasone propionate in a single inhaler is as efficacious in achieving asthma control and as well tolerated over a 28-week period as the two drugs administered individually.