Effect of cation content of certain ammoniomethacrylate copolymers type A (RL) and B (RS) on their binder property in tableting

Tablets of salicylic acid (drug model) have been formed using two analogous acrylatemethacrylate copolymers designated here as A and B as binders. A and B differ only in their content of quaternary ammonium (cationic) groups in the ratio 2:1 (A:B). The aim was to investigate the effect of the cationic groups on the tableting characteristics of the formed granules. In the procedure, aqueous dispersions of the polymers of concentrations 1 to 5% w/v were used in a separate experiment for granulation of the salicylic acid powder and then tableted. The final concentration of the binder in the tablets varied from 0.4 to 2% w/w. The parameters assessed were the tablet tensile strength (T) and their brittle fracture index (BFI) which are indicative of the plasto-elasticity of the granules; for instance, a high T value together with a low BFI value are indicative of a high plasto-elasticity. A and B generally displayed a strong binder property as they individually produced hard tablets even at the low concentration 0.4% w/w. As the binder concentration in the tablets increased to 2% w/w. tensile strength (MNm(-2)) increased from 1.08 to 1.80 (tablets of polymer A), 1.08 to 2.02 (tablets of polymer B). BFI values decreased from 0.24 to 0.06 (tablets of polymer A) and 0.16 to 0.04 (tablets of polymer B). These results indicate that the presence of the cationic groups in the polymer structure promoted elastic rather than plastic compression.