Background: The present study examined the duration of bronchodilation induced by nebulized glycopyrronium bromide (GB) and compared its effectiveness and incidence of any side effects with the combination of salbutamol and ipratropium bromide (SI) in critically ill mechanically ventilated chronic obstructive pulmonary disease (COPD) patients. Patients and methods: This prospective, observational study was conducted in mechanically ventilated adult patients of COPD (18–75 years). Data of two groups of patients were collected for 12 hours each for three consecutive days after the nebulization – Group I: those who received 25 µg of GB, and Group II: those who received 1.25 mg of levo-salbutamol and 500 µg of ipratropium by nebulization. Results: A significantly higher number of patients in group II had copious secretions. The mean static compliance was comparable at all time intervals, whereas the mean airway pressure was significantly lower in group II from 15 minutes to 4 hours post-nebulization. In group I, the onset of bronchodilation was 30 minutes on days 1 and 3, and 60 minutes on day 2, whereas, in group II, it was 60 minutes on days 1 and 2 and 30 minutes on day 3. In group I, bronchodilation was 10 hours on day 1 and 12 hours each on days 2 and 3, whereas in group II, bronchodilation was 4 hours on day 1 and 6 hours each on day 2 and 3. Conclusion: Compared with SI, GB nebulization resulted in lesser respiratory secretions, a longer duration of action in terms of lowered airway resistance, and no adverse effects like hypertension, tachycardia, or desiccation of respiratory secretions.