Mucoactive and antioxidant medicines for COPD: consensus of a group of Chinese pulmonary physicians

Abstract

Airway mucus hypersecretion is a frequent symptom associated with acute and chronic airway disease. Inhibition of mucus production or promotion of mucolysis not only relieved symptoms but also improved disease outcomes. There are numerous available mucoactive medicines for prescription, and how to select them properly for different diseases is important for clinical practice. So far, there is no one consensus or guideline reported. A group of Chinese pulmonary physicians worked together to complete this consensus based on literature review, summarized mechanism and usage of each classical mucoactive medicine. In general, antioxidant mucoactive medicines play an important role in chronic airway disease, including but not limited to airway mucus clearance, reduced acute exacerbation and improved pulmonary function.

Keywords: chronic bronchitis; mucolysis; sputum.

Figure 1

Mechanism of NAC pharmacology in COPD patients. Notes: NAC can directly break disulfide bonds in mucus to decrease mucus viscosity, thus improving ciliary beating and mucus clearance. NAC clears ROS through –SH binding, possessing antioxidant properties, as well as having the indirect function of facilitating GSH accumulation. The decrease of ROS and increase of GSH reduce airway inflammation and airway mucus production. All these contribute to improved lung function and reduced acute exacerbation. Abbreviations: –SH, thiol; GSH, glutathione; NAC, N-acetylcysteine; ROS, reactive oxygen species.

Figure 2

The synthesis of GSH from NAC and its metabolites. Notes: NAC is transferred to cysteine after deacetylation. Cysteine reacts with glutamate to become glutamylcysteine under the action of glutamylcysteine synthetase; then, glutamylcysteine and glycine yield GSH in the presence of glutathione synthetase. Abbreviations: GSH, glutathione; NAC, N-acetylcysteine.