Feasibility of testing bronchodilator responsiveness with glycopyrronium in obstructive airway diseases: the initial appraisal of the pilot experience

Abstract

Background: The short onset of action of glycopyrronium bromide, makes it a suitable antimuscarinic agent to test bronchodilator-responsiveness in airway diseases. The objective of the study was to explore the feasibility of the testing so. Methods: Subjects with features of airflow obstruction (FEV1/FVC < 0.07) were given to inhale a 50-μg single dose of dry powder of glycopyrronium bromide immediately following standard salbutamol-induced bronchodilator reversibility. A repeat spirometry was done after 30 minutes and the changes noted. The impact of both the drugs on spirometric variables suggesting airflow obstruction (FEV1. FEV1/FVC, and FEF25-75) were assessed statistically. A salbutamol-reversibility of ≥12% and >200ml was noted to differentiate asthmatics from chronic obstructive pulmonary disease (COPD) patients. Result: In a total of 35 subjects (asthma-10, COPD-25) with moderate baseline airflow obstruction [FEV1/FVC: 0.57 ± 0.12 and FEV1 (%predicted) as 46.17 ± 15.21], there was global improvement across the spirometric variables to serial inhalation of salbutamol and glycopyrronium. The post salbutamol changes in FEV1 (absolute value) were significant (P = 0.0001) overall and also for both asthma and COPD. Following inhalation of glycopyrronium, the changes were again significant for overall (P = 0.0001), asthma (P = 0.0065), and COPD (P = 0.0001). The parallel change in FEF25-75 was, however, showing better reversibility in asthma (P = 0.0008) with salbutamol compared to COPD (P = 0.1846) and the reverse to glycopyrronium inhalation that results in better reversibility in COPD (P = 0.0085) compared to asthma (P = 0.0949). Conclusion: Testing the reversibility with glycopyrronium appears feasible and safe in obstructive airway disease. It induced add-on reversibility once used after standard salbutamol reversibility. The observation demands further evaluations.