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 (https://www.umin.ac.jp/. ID. UMIN000012043).