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Role of mucoactive agents and secretion clearance techniques in COPD

Loutfi Sami Aboussouan, MD
Section Editor
James K Stoller, MD, MS
Deputy Editor
Helen Hollingsworth, MD


Tracheobronchial mucus contributes significantly to the symptoms of chronic obstructive pulmonary disease (COPD). It is a diagnostic criterion for chronic bronchitis and one of the primary causes of airflow obstruction. In addition, chronic mucus hypersecretion is associated with increased mortality, an accelerated decline of forced expiratory volume in one second (FEV1), and an increased risk of hospitalization in COPD [1-3].

The role of mucoactive therapy in the management of COPD will be reviewed here. The role of mucoactive agents in the treatment of cystic fibrosis (CF) lung disease and non-CF bronchiectasis is discussed separately. (See "Cystic fibrosis: Overview of the treatment of lung disease" and "Treatment of bronchiectasis in adults".)


A mucoactive drug is defined as an agent with the capability of modifying mucus production, secretion, its nature and composition, or its interactions with the mucociliary epithelium [4]. Examples of mucoactive drugs include expectorants (induce cough or increase the volume of secretions), mucolytics (reduce the viscosity of mucus), mucokinetic drugs (increase the mobility and transportability of mucus), and mucoregulators (control the process of hypersecretion) [5].


The surface liquid covering the epithelial lining of the airways comprises at least two layers: the mucus layer (gel) and the periciliary layer surrounding the cilia [6,7]. In contrast to traditional models where the periciliary layer is assumed to be liquid (sol), a more current model consider it as consisting of a gel mesh of cell-tethered mucins and polysaccharides [8]. Mucus consists of a mixture of transudative fluid and secretions from surface epithelium and submucosal glands. It is predominantly composed of water (95 percent) and glycoproteins (2 to 3 percent), with smaller components of proteoglycans (0.1 to 0.5 percent), lipids (0.3 to 0.5 percent), proteins, and DNA [9]. The glycoprotein component consists of secreted mucins, particularly the large polymeric structures MUC5AC and MUC5B, which account for the rheologic properties (ie, properties governing flow) of mucus [10].

Mucus is a movable barrier that maintains hydration and contains defense factors against various pathogens [10]. The normal volume of mucus secretion is approximately 15 mL/day [11], with a mucociliary clearance of 50 micrometers/second [12].

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Literature review current through: Nov 2017. | This topic last updated: Oct 27, 2017.
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