Drug release from a new family of graft copolymers of methyl methacrylate .1.

Hydrophilic matrices are an interesting option when developing an oral drug release device. In this work we have produced hydrophilic matrices tablets by direct compression. Previously graft copolymers were synthesized as an important component of the tablets: hydroxypropyl starch-methyl methacrylate (HS-MMA), carboxymethyl starch-MMA (CS-MMA) and hydroxypropyl cellulose-MMA (HC-MMA). The polymeric component was mixed with Emcompress(R), stearic acid and theophylline. All the products fulfilled the requirements for good flow according to literature. L-formulations show lower values of plasticity than O-formulations. However, L-formulations exhibit higher compactibility values than O-formulations. In general, all the formulations with O-polymers show faster release of the drug at three pHs used. On the other hand, these tablets have the capacity to hydrate quickly forming a gelatinous layer, so it is necessary to achieve controlled drug release from hydrophilic matrices. In relation with the dissolution efficiency over 8 h, formulations with HS-MMAL and NaCMC show very similar results, although the release of theophylline from NaCMC tablets at different pHs was always slightly slower than HS-MMAL tablets. (C) 1997 Elsevier Science B.V.