Computed tomography (CT)-assessed bronchodilation induced by inhaled indacaterol and glycopyrronium/indacaterol in COPD.

BACKGROUND

Our previous studies suggested that the site of bronchodilation on CT might differ between inhaled β2 agonists and inhaled anticholinergics in COPD.

AIM: To assess and compare the bronchodilation effects of inhaled indacaterol and glycopyrronium/indacaterol by airway generation in large airways using CT.

METHODS

CT scans at full inspiration and pulmonary function tests were done in 25 patients with moderate-severe COPD before and 4-5 weeks after daily inhalation of indacaterol and again another 4-5 weeks after inhalation of glycopyrronium/indacaterol. Airway inner luminal area (Ai) at the 3rd (segmental) to 6th generation of 8 selected bronchi, a total of 32 sites, in the right lung was analyzed on 3 occasions. Our proprietary software enables us to select the same airways and the same measurement sites for comparison, with simultaneous confirmation using two screens on the computer.

RESULTS

The overall increase of Ai (ΔAi, %) averaged at all 32 measurement sites induced by glycopyrronium/indacaterol had a significant correlation with FEV1 improvement (r = 0.7466, p < 0.0001). Both ΔAi, % with indacaterol and ΔAi, % with additional glycopyrronium were significant at the 3rd to 6th generations. Remarkable increases in ΔAi, % were found at the 5th and 6th generations in several subjects with indacaterol or additional glycopyrronium. There were no significant site-differences in the bronchodilation pattern caused by indacaterol and by glycopyrronium/indacaterol at any of the 3rd to 6th generations.

CONCLUSIONS

Additional bronchodilation with glycopyrronium was demonstrated by CT at the 3rd to 6th generations, with no site-specific differences in bronchodilation between indacaterol and glycopyrronium/indacaterol. This study was registered in the UMIN Clinical Trials Registry (UMIN-CTR) system (http://www.umin.ac.jp/. ID. UMIN000012043).