Formulation and evaluation of metformin hydrochloride extended release tablets

Abstract

Metformin  hydrochloride has  relatively  short  plasma  half-life,  low  absolute  bioavailability. The  need  for  the administration two to three times a day when larger doses are required can decrease patient compliance. Sustained release formulation that would maintain plasma level for 8-12 h might be sufficient for daily dosing of metformin. Sustained release products are needed for metformin to prolong its duration of action and to improve patient compliances. The overall objective of this study was to develop an oral sustained release metformin hydrochloride tablet by using polymers like Methocel K100M CR, Polyox WSR 303, Ethocel 100 cps as rate controlling factor. The tablets were prepared by wet granulation method. The precompression blend was tested for angle of repose, bulk density, tapped density, compressibility index and Hausner‟s ratio. The tablets were evaluated for weight variation, hardness, friability, dissolution rate, content uniformity, and were found to be within standard limit. The invitro dissolution study was carried out using USP II apparatus method and the data was analysed using zero order, first order, Higuchi, Korsmeyer and Hixson-Crowell equations. The drug release study revealed that F5 shows sustain the drug release for more than 12 h. Kinetic modeling of in vitro dissolution profiles revealed the drug release mechanism ranges from diffusion controlled or Fickian transport to anomalous type or non-Fickian transport.