Modification of solute dissolution rate by coprecipitation with certain acrylate–methacrylate copolymers

Coprecipitates containing certain cationic acrylate-methacrylate copolymers and paracetamol (polar solute) have been prepared by evaporating to dryness an ethanolic solution of both components; their friability (i.e., degree of crumbling to dust under impact stress) and dissolution characteristics were evaluated. Friability decreased with increase in the polymer content of the coprecipitates; this effect was more marked in the polymer system containing the higher cation content. Dissolution rates also decreased with increase in polymer content, but this time the effect was slightly more pronounced in the polymer system with the lower cation content. It is thought that the polymer cationic groups interacted with polar groups of the solute to increase coherence of the particle; on the other hand, the cationic groups confer hydrophilic character and at certain concentrations, > 5% they may promote swelling in aqueous fluids and hence weaken bonding forces in the solute-polymer particle with a tendency to reduce the polymer effect on dissolution rate.