Formulation and Optimization of Valsartan Sustained Release Tablets Using Natural Polymer Matrices

Abstract

This research aimed to develop and optimize sustained-release Valsartan tablets utilizing natural hydrophilic polymers to enhance therapeutic reliability and patient compliance. Nine matrix formulations (VT1–VT9) were created using direct compression using Guar Gum, Xanthan Gum, and Tamarind Seed Polysaccharide (TSP), both singly and in combination. All powder blends demonstrated acceptable precompression properties, with a Carr’s Index of 12–15%, a Hausner’s ratio of 1.15–1.18, and an angle of repose of less than 30°, indicating their appropriateness for direct compression. The post-compression results indicated a consistent thickness (3.10–3.18 mm), satisfactory hardness (6.1–6.5 kg/cm²), friability <0.5%, and drug content ranging from 98–99%, confirming adherence to pharmacopeial criteria.

In vitro dissolution tests indicated that the release of Valsartan diminished with higher polymer concentrations due to the development of a hydrated gel barrier. Single-polymer matrices released substances during 10–12 hours, whereas Xanthan Gum demonstrated much enhanced control. The combination polymer systems (VT8 and VT9) exhibited the most favorable release characteristics, with VT9 attaining a cumulative release of 99.27% at 12 hours without a burst effect. Release kinetics demonstrated First-order/Higuchi diffusion for single-polymer batches, while combination matrices exhibited Zero-order release with non-Fickian processes (n = 0.83–0.90). VT9 was determined to be the optimized formulation, providing reliable and prolonged drug release appropriate for once-daily antihypertensive treatment.