In-vitro comparison of the mucolytic activity of sodium metabisulfite, n-acetylcysteine and dithiothreitol

Using the in vitro mucin model, sodium metabisulfite was shown to exhibit considerable mucolytic activity. Compared on a molar basis, it is less powerful in viscosity reduction than dithiothreitol but stronger than N-acetylcysteine, which is currently the most often used mucolytic agent. Combinations of sodium metabisulfite and N-acetylcysteine at relatively low concentrations exhibited equivalent and pronounced mucolytic activity as that produced by a high concentration of N-acetylcysteine. The possibility of combining two or more mucolytic agents at low concentrations to give a less toxic but, nevertheless, effective product is raised. Finally, the in vitro mucin model appeared to be incapable of distinguishing highly mucolytic solutions, and caution must be exercised in utilizing this model for testing such solutions.