Formulation and Evaluation of Sustained Release Tablet of Metformin by Ionic Gelation Technique using Sida acuta Gum as Release Retardant

Abstract

This research was done to formulate and assess the sustained release property of metformin tablets prepared from metformin microcapsules produced by ionic gelation technique using Sida acuta gum or sodium carboxymethylcellulose as release retardant. Sida acuta gum was produced by isopropyl alcohol precipitation of the filtrate obtained from distilled water maceration of powdered dried Sida acuta leaves. Metformin and Sida acuta gum compatibility was determined using FTIR. Metformin microcapsules were prepared by ionic gelation technique using sodium alginate alone or with either Sida acuta gum or sodium carboxymethylcellulose as release retardant. The microcapsules were evaluated for % yield and flow properties. The size and surface morphology of the microcapsules were determined using scanning electron microscopy. Metformin tablets were prepared from the microcapsules using direct compression technique. The tablets were evaluated for hardness, friability and in vitro dissolution. There was no major incompatibility between metformin and Sida acuta gum. The microcapsules have excellent flow property and were of micrometer size range. They have rough surfaces. The friability of the tablets ranged from 0.4-1.6% while the hardness was from 3.82-11.17 Kgf. The tablets from formulations M2 failed both friability and hardness test. About 44.5-47.1% of metformin was released from the tablet formulations after 6 h while 86.0-100% was released after 10 h. All the tablet formulations showed sustained release ability. Keywords: Microcapsules, metformin, Sida acuta gum, sustained release, ionic gelation