Rheological assessment of mucolytic agents on sputum of chronic bronchitics.

In vitro and in vivo studies were made on the sputum of chronic bronchitics using a Ferranti-Shirley cone and plate viscometer and a new stress relaxation method. The latter utilized a modified chemical balance and permitted study at very low shear rates. The results from simpler apparatus correlated well with the data obtained with the cone and plate viscometer. Significant reduction in four chosen parameters of viscosity occurred in vitro with N-acetylcysteine and with ascorbic acid-hydrogen peroxide-cupric ion complex (A.A.H.Cu.), but not with 4-molar urea. In vivo studies showed that, using freshly prepared A.A.H.Cu in an efficient hospital nebulizer, a statistically significant reduction in the four viscosity parameters occurred with subjective ease of expectoration. Nebulization of A.A.H.Cu performed with a simpler domestic-type nebulizer did not produce satisfactory reduction of viscosity or ease of expectoration. Rheological methods previously employed to study mucus and mucolytic agent activity are briefly reviewed.