Effects of formoterol-budesonide combination on residual eosinophilic inflammation in distal airway of patients with well-controlled moderate asthma

Aims: To investigate whether formoterol-budesonide combination (FBC, Symbicort TM) controls residual eosinophilic inflammation in the distal airways of well-controlled asthmatic patients more effectively than salmeterol-fluticasone propionate combination (SFC). Methods: Twenty eight outpatients (58.4±19.7yrs) with well-controlled moderate asthma who had used SFC for more than 3 months were the subjects. Evidence of eosinophilic cationic protein (ECP) and surfactant protein D (SP-D) in 10% hypertonic saline-induced sputum was assessed, together with pulmonary fuction testing, impulse oscillometry system (IOS) and exhaled nitric oxide (FeNO). Results: Eosinophilic inflammation was detected in the distal airway of eleven patients (39.3%) and they were switched to FBC (4,5/160ug, 2 inhalations twice daily). As higher levels of sputum SP-D were obtained from the nearer peripheral airway area, significantly higher ECP levels in late-phase sputum may indicate residual asthmatic inflammation in the peripheral airway. The ECP levels in late-phase sputum) 255.2±297.1ug/1 at study entry) significantly decrease 60.0±43.7 (p=0.038) and 50.7±48.4 (p0.049) at 4 and 8 weeks after switching to treatment with the FBC, respectively. The FeNo levels (76.0±69.4 ppb at study entry) also significantly decreased 29.1±15.7 (p=0.017) at 8 weeks. The R5-R20 and AX values of IOS parameters also significantly improved after 8 weeks. Conclusion: This study suggests that the FBC may give better control of residual eosinophilic inflammation in the distal airway compared to SFC therapy.