FORMULATION AND RELEASE CHARACTERISTICS OF HPMC MATRIX TABLETS OF METOPROLOL SUCCINATE

The objective of this study was to design and evaluate oral sustained drug delivery system for Metoprolol succinate using pH sensitive polymer HPMC and sodium alginate and to evaluate its efficacy in reducing the hypertension. The drug filler blend was mixed with various concentrations of hydrophilic polymers such as HPMC, sodium alginate and combination of both the matrixing agents. The tablets were prepared by wet granulation method. Matrix tablets were evaluated for weight variation, content uniformity, friability, hardness, thickness, swelling index, and in vitro dissolution. The assays of different formulations were determined and the drug content was found between 85-115%. The weight variation was observed to be within the prescribed limits for each formulation. In-Vitro drug release studies carried out with different formulation tablets in 0.1N HCl for 2hrs, pH 6.8 phosphate buffer for 12hrs. Up to 2 hr study the formulation shows low release in gastric medium (0.1N HCl). From the 2 hr up to 12 hr study percentage of drug release was increased in intestinal fluid (pH 6.8 buffer). In these studies, the F1, F3 and F5 formulations showed the better drug release in compared to others. By swelling index it was concluded that the tablet shows matrix type of release in the intestine. These formulations follow zero order release kinetics known by Higuchi plot. The matrix formulation F1, F3 and F5 showed sustained release of Metoprolol succinate by the diffusion mechanism. Studies reveal that HPMC, sodium alginate sustained release matrix tablets can drive and make available the intact drug for local action for hypertension treatment.