Mucoactive agents are a class of chemical agents which aid in the clearance of mucus from the upper and lower airways, including the lungs, bronchi, and trachea. Mucoactive drugs include expectorants, mucolytics, mucoregulators, and mucokinetics. These medications are used in the treatment of respiratory diseases that are complicated by the oversecretion or inspissation of mucus. These drugs can be further categorized by their mechanism of action.
Mechanism of action
- Expectorants – increase airway water or the volume of airway secretions
- Mucolytics – thin (reduce the viscosity of) the mucus
- Mucokinetics – increase transportability of mucus by cough
- Mucoregulators – suppress underlying mechanisms of mucus hypersecretion
In general, clearance ability is hampered by the bonding to surfaces (stickiness), and by the viscosity of mucous secretions in the lungs. In turn, the viscosity is dependent upon the concentration of mucoprotein in the secretions.
Expectorants and mucolytic agents are different types of medication, yet both are intended to promote drainage of mucus from the lungs.
An expectorant (from the Latin expectorare, to expel or banish) works by signaling the body to increase the amount or hydration of secretions, resulting in more yet clearer secretions and as a byproduct lubricating the irritated respiratory tract.
One expectorant, guaifenesin, is commonly available in many cough syrups and also as long release tablets. Mucolytics can dissolve thick mucus and are usually used to help relieve respiratory difficulties. They do this by breaking down the chemical bonds between molecules in the mucus. This in turn can lower the viscosity by altering the mucin-containing components.
Any of these effects could improve airway clearance during coughing.
An expectorant increases bronchial secretions and mucolytics help loosen thick bronchial secretions. Expectorants reduce the thickness or viscosity of bronchial secretions thus increasing mucus flow that can be removed more easily through coughing. Mucolytics break down the chemical structure of mucus molecules. The mucus becomes thinner and can be removed more easily through coughing.— Adams, Holland, & Bostwick, 2008, p. 591
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- Adams, Michael; Holland, Leland Norman; Bostwick, Paula Manuel (2016). Pharmacology for Nurses: A Pathophysiologic Approach (5 ed.). Pearson Education. p. 960. ISBN 978-0134255163.
- Rubin, Bruce K (1 July 2007). "Mucolytics, Expectorants, and Mucokinetic Medications". Respiratory Care. 52 (7).