['Combination therapy with an inhaled corticosteroid (ICS) and a long-acting β2-agonist (LABA) in a single inhaler is the mainstay of asthma management. We previously showed that switching from salmeterol/fluticasone combination (SFC) 50/250 μg bid to a fixed-dose formoterol/budesonide combination (FBC) 9/320 μg bid improved asthma control and pulmonary functions, but not fractional exhaled nitric oxide (FeNO), in patients with asthma not adequately controlled under the former treatment regimen.', 'To assess whether switching from SFC to FBC improves peripheral airway/alveolar inflammation in asthma (UMIN000009619).', "Subjects included 66 patients with mild to moderate asthma receiving SFC 50/250 μg bid for more than 8 weeks. Patients were randomized into FBC 9/320 μg bid or continued the same dose of SFC for 12 weeks. Asthma Control Questionnaire, 5-item version (ACQ5) score, peak expiratory flow, spirometry, FeNO, alveolar NO concentration (CANO), and maximal NO flux in the conductive airways (J'awNO) were measured.", "Sixty-one patients completed the study. The proportion of patients with an improvement in ACQ5 was significantly higher in the FBC group than in the SFC group (51.6% vs 16.7%, respectively, p = 0.003). A significant decrease in CANO was observed in the FBC group (from 8.8 ± 9.2 ppb to 4.0 ± 2.6 ppb; p = 0.007) compared to the SFC group (from 7.4 ± 7.8 ppb to 6.4 ± 5.0 ppb; p = 0.266) although there was no significant difference in the changes in pulmonary functions between the 2 groups. Similar significant differences were found in the CANO corrected for the axial back diffusion of NO (FBC, from 6.5 ± 8.2 ppb to 2.3 ± 2.5 ppb; and SFC, from 4.3 ± 5.3 ppb to 3.9 ± 4.3 ppb). There was no difference in the changes in FeNO or J'awNO between the 2 groups."] Does switching from salmeterol/fluticasone to formoterol/budesonide combinations improve peripheral airway/alveolar inflammation in asthma?