In vitro evaluation of sustained-release matrix tablets prepared with new modified polymeric carbohydrates

The study of the rheological and compressional properties of sustained-release matrix tablets prepared with new polymers obtained by graft copolymerization of methyl methacrylate (MMA) on various carbohydrates is the main purpose of this work. All the mixtures had good flow properties, showing cellulose derivatives mixtures the best values. Powders without homopolymers showed a statistically significant lower flow rate than mixtures with homopolymers. All the mixtures with hydroxypropyl starch polymers showed better statistically significant compactibility and plasticity than the hydroxypropyl cellulose derivatives. Practically all the mixtures accomplished with the requirements of direct compression excipients in relation with lubrication coefficient. All the tablets elaborated with mixtures with homopolymers required a total work lower than the mixtures without homopolymers. Tablets from all products passed the test for weight uniformity, except the tablets of carboxymethyl starch (CS-MMA) without homopolymer. Only hydroxypropylcellulose tablets demonstrated an acceptable friability. Only standard tablets and CS-MMA without homopolymers exhibited disintegration times higher than 30 min. A clearly different behaviour between the new polymers and the standards was observed in relation with dissolution test.