mucolytic
A mucolytic thins thick, sticky lung mucus so it becomes easier to cough up, much like adding water to a gluey paste to make it pour. When phlegm is too tenacious to clear, a mucolytic loosens it.
Drugs like carbocisteine, acetylcysteine and ambroxol reduce the viscosity of respiratory mucus. Acetylcysteine breaks the disulfide bonds that cross-link mucus glycoproteins, while carbocisteine alters the composition of secretions toward a more fluid state. Easier-to-clear mucus can reduce the frequency of flare-ups in some chronic lung conditions such as COPD and bronchiectasis. Acetylcysteine separately has a major role as the antidote in paracetamol overdose, a different use from its mucolytic action.
The benefit of mucolytics is modest and they are not the right tool for every cough; they suit chronic conditions with thick, hard-to-clear sputum rather than ordinary self-limiting colds. They are generally well tolerated, with occasional stomach upset, and adequate hydration and chest physiotherapy remain important partners in clearing secretions.
A patient with COPD and thick sputum takes carbocisteine to make secretions easier to clear and reduce flare-ups.
Carbocisteine lowers mucus viscosity so phlegm is easier to expectorate.
Acetylcysteine has two distinct roles: as an inhaled or oral mucolytic and, in a very different context, as the antidote for paracetamol overdose.