Formulation and evaluation of sustained release matrix tablets of metformin hydrochloride

Abstract

Metformin hydrochloride is an oral hypoglycemic agent widely used in the treatment of type II (non insulin dependent) diabetes mellitus. The objective of this work was to asses the effect of drug: polymer ratio and HPMC viscosity grade on the release of metformin Hcl from hydrophilic polymeric matrices. Matrix tablets of metformin HCl were formulated using a hydrophilic swellable polymer, HPMC, with lactose as diluent. Three different grades of polymer i.e., K4M, K15M, K100M were used in three different ratios ( 2:1, 4:1, 6:1) to retard the drug release from the matrices. Magnesium stearate and colloidal silicon dioxide were used as excipients. All the formulations prepared were found to comply with the official tests for all physical parameters like wt.variation, friability, drug content uniformity and in-vitro dissolution studies. The lower viscosity grade polymer showed a greater drug release from the matrices than the higher viscosity grades. The higher drug: polymer ratio (i.e., 6:1) showed a greater drug release than the others.