Testing Bronchodilator Responsiveness with Glycopyrronium after Salbutamol: Appraisal of an Independent Class Specific Effect of Antimuscarinic Agent

Background:The assessment of the responsiveness to glycopyrronium, an antimuscarinic agent, has recently, been forwarded serial to salbutamol responsiveness in spirometry for the obstructive airway diseases.It is important to appreciate that the post-glycopyrronium improvement is not influenced by the preceding salbutamol inhalation.Methods: Suspected obstructive airway disease (OAD) patients were selected from outpatient department with written consent.They underwent spirometry and salbutamol reversibility observing guideline recommendations.Immediate to the postbronchodilator (salbutamol) spirometry, the subjects were randomized to inhale either (1) glycopyrronium dry powdered inhaler (DPI) (50 gm) or (2) placebo MDI (4 puffs) and the impact was assessed after 30 min of inhalation.Results: We had 48 patients in each group for placebo (mean age 57.58 14.62) or glycopyrronium (mean age 52.54 19.29) to note the add-on reversibility.While the glycopyrronium inhalation resulted in an unequivocal and universal improvement in forced expiratory volume in 1 second (FEV1), a universal but mild reduction of FEV1 marked the impact of placebo inhalation.The add-on effect of glycopyrronium has been found as significant in OAD as a whole (p = 0.0017) and for asthma (p = 0.05; n = 14) and chronic obstructive pulmonary disease (COPD) (p = 0.0304; n = 12). Conclusion:The claimed glycopyrronium reversibility in the serial testing protocol after testing salbutamol reversibility is independent and class-specific of the antimuscarinic agent and not a continued effect of salbutamol.