2. Formulation and evaluation of Ranolazine sustained release matrix tablets using Eudragit and HPMC

In the present work, an attempt was made to formulate sustained release matrix tablets for Ranolazine using Eudragit L 100-55 and different viscosity grades of HPMC (Methocel E50 and Methocel K15M CR). The matrix tablets were prepared by direct compression process. The prepared tablets were evaluated for various physico chemical parameters. In vitro drug release study was carried out in simulated gastric fluid (0.1 N HCl) for the first 2 h and in phosphate buffer (pH 6.8) for the next 6 h following USP 25 paddle method. Increase in Eudragit L 100-55 and HPMC concentrations or increase in viscosity grades of HPMC polymers (Methocel E50 and Methocel K15M CR) resulted in a significant decrease in Ranolazine release. For instance, the matrix tablets containing 15% of polymers shows delayed and extended drug release when compared to 10% polymers irrespective of viscosity grades of HPMC in the tablet. Further, the drug release from Eudragit L 100-55 and higher HPMC viscosity grades (Methocel K15M) was slower as compared to lower viscosity grades (Methocel E50). The in vitro data is fitted in to different kinetic models and the best-fit was achieved with the Higuchi model followed by the zero-order plot, Korsmeyer and Hixson Crowell equations. The release of Ranolazine from matrix tablets containing high Eudragit L 100-55 and HPMC (Methocel K15M CR) content was prolonged as a result; an oral sustained release dosage form to circumvent the frequency of administration has been achieved.