PURPOSE: This paper presents a new rheological approach, based on a stationary viscoelastic test (creep test), to describe the interaction between a mucoadhesive polymer and mucin. METHODS: An automated model builder tool is used to identify accurate compliance models from experimental data. This approach is applied to study the interaction of gastric porcine mucin with three viscosity grades of a mucoadhesive polymer, sodium carboxymethylcellulose. RESULTS: By comparing the compliance models of polymer solutions and their mixtures with mucin, prepared at different concentrations and concentration ratios, we observed an increase in the order of the model of the mixtures at the lowest polymer concentration for all the three viscosity grades; this effect is more pronounced for the low viscosity grade. On the other hand, an increase in mucin concentration does not result in a further increase in model order, but rather in a decrease in retarded compliance and an increase in newtonian viscosity. CONCLUSIONS: We interpret the model order as the number of different interactions between polymer and mucin, and the parameter values as a measure of their strength. The results indicate the suitability of the approach for a deep characterization of the interactions involved in mucoadhesion.
PURPOSE: This paper presents a new rheological approach, based on a stationary viscoelastic test (creep test), to describe the interaction between a mucoadhesive polymer and mucin. METHODS: An automated model builder tool is used to identify accurate compliance models from experimental data. This approach is applied to study the interaction of gastric porcine mucin with three viscosity grades of a mucoadhesive polymer, sodium carboxymethylcellulose. RESULTS: By comparing the compliance models of polymer solutions and their mixtures with mucin, prepared at different concentrations and concentration ratios, we observed an increase in the order of the model of the mixtures at the lowest polymer concentration for all the three viscosity grades; this effect is more pronounced for the low viscosity grade. On the other hand, an increase in mucin concentration does not result in a further increase in model order, but rather in a decrease in retarded compliance and an increase in newtonian viscosity. CONCLUSIONS: We interpret the model order as the number of different interactions between polymer and mucin, and the parameter values as a measure of their strength. The results indicate the suitability of the approach for a deep characterization of the interactions involved in mucoadhesion.