Vol. 2, Issue 1, Part A (2025)

Background: Metformin hydrochloride (MH) is the first-line oral antihyperglycemic agent for managing type 2 diabetes mellitus, but its short half-life and gastrointestinal intolerance necessitate frequent dosing. Sustained-release (sustained-release) formulations can overcome these limitations by maintaining therapeutic plasma concentrations for extended periods.
Objective: The present study aimed to formulate and evaluate sustained-release matrix tablets of MH using natural polymers as rate-controlling agents to achieve prolonged drug release, reduced dosing frequency, and improved patient adherence.
Methods: Matrix tablets were prepared using the wet granulation technique with natural polymers such as guar gum, xanthan gum, sodium alginate, and tamarind kernel powder, both individually and in combination. The granules and tablets were evaluated for pre- and post-compression parameters as per pharmacopeial standards. In-vitro drug release was performed in simulated gastrointestinal fluids over 12 hours and analyzed using kinetic models (zero-order, first-order, Higuchi, and Korsmeyer-Peppas equations) to elucidate the release mechanism.
Results: All formulations exhibited satisfactory mechanical and physicochemical properties. Increasing the polymer concentration produced a significant reduction in drug release rate. Among all batches, the formulation containing xanthan gum and sodium alginate (F6) achieved optimal sustained release (approximately 93-94% in 12 hours) with near zero-order kinetics. Drug release followed the Higuchi model (R² > 0.99), and the release exponent (n = 0.58-0.65) indicated an anomalous diffusion mechanism involving both diffusion and erosion. Statistical analysis (ANOVA, p<0.001) confirmed that the polymer type significantly influenced the release rate.
Conclusion: The study concludes that natural polymers are effective, economical, and eco-friendly alternatives to synthetic polymers for developing sustained-release metformin formulations. The optimized xanthan-alginate matrix system achieved controlled release over 12 hours, suggesting its potential to enhance therapeutic efficacy, reduce dosing frequency, and improve patient compliance in long-term diabetes management. The findings provide a foundation for future in-vivo and stability studies to advance natural polymer-based sustained-release technologies.