In the present study which the aim to evaluate the effect of hydrophilic polymer on the biopharmaceutical properties of metformin hydrochloride floating tablets, we have prepared floating systems using melt granulation, according to effervescent approach. Two hydrophilic polymers are used at various concentrations (10, 12.5, 15 and 17.5%), Acacia gum and hydroxypropylmethylcellulose (HPMC) at three viscosity grades (K4M, K15M and K100M). In addition to the satisfactory physical parameters, the evaluation of buoyancy and in vitro dissolution of floating developed systems revealed that the biopharmaceutical performances of these systems depended on the nature of the polymer. Unlike the acacia gum which did not produce floating systems, the HPMC matrixes had good buoyancy properties: fast buoyancy time (24030 to 360±30 sec) and total flotation time more than 24 hours with matrix maintained integrity. In addition, in the case of HPMC, a significant influence of viscosity grade on MTH kinetics has been demonstrated. Indeed, the observed results showed that at 17.5% of HPMC, as the viscosity grade increases, the dissolution kinetics of metformin HCl was extended. The formulations F8 (HPMC K15M) and F12 (HPMC K100M) have exhibited the drug release rates of about 92 and 80% respectively at the end of 8 hours dissolving. These formulations followed Korsmeyer-Peppas/Higuchi release kinetics according to a Non-Fickian mechanism. Finally, the melting granulation process of MTH with stearic acid, in the case of HPMC K100M, used at high concentration (17.5%), has allowed the development of extended-release effervescent floating tablets ( 8 h).

Purpose: The aim of this study was to evaluate the combined effect, acacia gum(AG)/ hydroxypropylmethylcellulose (HPMC), on biopharmaceutical performances of floating tablets of metformin hydrochloride (MTH) prepared by thermoplastic granulation using stearic acid. Methods: We have prepared the matrixes using AG/HPMC as a polymer combination. This combination of polymers which represents 15% of the total mass of tablet was used at various ratios 3:1, 1:1, 1:3, with two viscosity grade of HPMC (k15M and k100M). The developed matrixes have been evaluated for their pharmacotechnical and biopharmaceutical properties. Results: In addition to the satisfactory physical characteristics of matrixes, it was revealed that the Fc3 and Fc6 formulations with AG/HPMC k15M and AG/HPMC k100M respectively, at ratio, 1:3 were considered the most performance. These formulations have shown swelling, fast flotation, 360 and 480 seconds respectively, and remained floating on the surface of the medium for more than 24 hours, with the matrix integrity, while F1, containing only AG, did not show swelling and did not float. In addition, extended in vitro release (>8 hours) with decreased dissolved MTH rates was demonstrated for Fc3 and Fc6 matrixes, 95% and 91% respectively, compared to F1 where MTH dissolution was complete after 2 hours. The drug release from the highest-performance matrixes (Fc3 and Fc6) was found to follow Korsmeyer-Peppas’s model. The mechanism drug release was controlled by diffusion and erosion. Conclusion: The AG/HPMC combination was suitable as a polymer matrix to improve the in vitro biopharmaceutical properties of MTH compared to AG.

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