INFLUENCE OF MEDIUM ON DISSOLUTION-EROSION BEHAVIOR OF NA CARBOXYMETHYLCELLULOSE AND ON VISCOELASTIC PROPERTIES OF GELS

The relevance of the theological properties of a gelled polymer on its dissolution behaviour was investigated in the case of a high viscosity grade Na carboxymethylcellulose (NaCMC). Creep viscosity and oscillatory test parameters were measured on NaCMC gels in distilled water and in pH 6.8 phosphate buffer. Gel concentration ranged between 2.5 and 4.0% w/w. Polymer erosion from gels and from tablets was also tested in the same media and the results were in line with theological data. Moreover, the effect of ionic strength and ion type on both theological properties of gels and erosion from tablets was assessed. A relationship was also found in this case between theological parameters and erosion rates. The importance of ionic strength on the rheological and erosion behaviour of polyelectrolytes such as NaCMC is highlighted.