Evaluation of Sputum Clearance
The success of bronchial secretion elimination depends on several key factors:
- Rheological properties of sputum: these include viscosity, elasticity, surface tension, osmolarity, and adhesiveness (stickiness).
- Volume of secretion: the total amount of mucus produced.
- Mucociliary clearance: the coordinated functional activity of the bronchial ciliated epithelium.
Mucolytics vs. Secretomotor Agents: What Is the Difference?
In clinical practice, it is important to clearly distinguish between two approaches to thinning sputum:
- Mucolytic agents directly affect the structure of the secretion. Their primary effect is reducing the viscosity and stickiness of sputum through depolymerization and breakdown.
- Secretomotor agents work differently. They increase the volume of the fluid component of the secretion (which secondarily thins mucus via dilution) and stimulate the motility of the ciliated epithelium by activating ciliary movement.
Classification of Mucolytics by Composition
The modern pharmacological arsenal of mucolytic drugs is divided into two major categories:
- Synthetic drugs: familiar agents such as acetylcysteine, carbocisteine, ambroxol, and bromhexine.
- Enzymatic preparations: used less frequently as mucolytics, subdivided into proteolytic enzymes (trypsin, chymotrypsin) and nucleases (ribonuclease, deoxyribonuclease).
Characteristics of Enzymatic Mucolytics
Enzymatic preparations possess specific mechanisms of action on bronchial secretions:
- Proteolytic enzymes (trypsin, chymotrypsin) cleave peptide bonds directly within the protein matrix of the sputum.
- Nucleases (RNase, DNase) cause depolymerization of nucleic acids—DNA and RNA—which accumulate in large quantities in pus and decaying cells.
A prominent representative of this subgroup is recombinant human deoxyribonuclease (dornase alfa), known under the trade name Pulmozyme. This drug is administered via inhalation.