Mucolytics are medications taken to soften mucus in the respiratory tract, so that it can be coughed up more easily. They work by making the mucus less viscous (thick and sticky). Bronchiectasis is among the diseases that mucolytics may be used to treat, as they help in clearing mucus from the airways.

Mucolytics for bronchiectasis: mechanism of action

There are two types of mucolytics, the “classic” and the “peptide.” Those defined as “classic” work by acting on the formative stages of mucus, within the mucus-secreting cells. They break the structure of fibers in mucoid sputum, producing a less viscous mucus that’s easier to expel. Some examples of “classic” mucolytic agents are bromhexine, N-acetylcysteine, erdosteine and fudosteine.

The “peptide” mucolytics are designed to break down the DNA and protein network that is characteristic of pus. Dornase alfa is an enzyme that targets these networks, and is used for the treatment of mucus hypersecretion.

Clinical trials

A Phase 4 study (NCT02088216) evaluating whether N-acetylcysteine could reduce the frequency of acute exacerbations in people with non-cystic fibrosis bronchiectasis, improving their quality of life, is currently ongoing. The randomized and placebo-controlled study in about 150 adults is testing the treatment at 600 mg, given twice a day for 12 months, with a primary goal of measuring its effect on the number of acute exacerbations experienced over three months. Other study objectives include measures of sputum volume in 24 hours, changes in the nature of sputum, changes in FEV1, and FVC (two measures of lung health), and the time to first exacerbation and to recurrent exacerbations.


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