Design and Characterization of Valsartan Gastro retentive Floating Raft Gel Using Natural–Synthetic Polymer Combinations for Enhanced Bioavailability

Abstract

This research aimed to develop and assess gastro retentive floating raft gels containing valsartan by utilizing a blend of natural and synthetic polymers to improve stomach retention time and oral bioavailability. Six formulations (VR1–VR6) were created using sodium alginate, gellan gum, HPMC K15M, calcium carbonate, and sodium bicarbonate to facilitate in-situ gelation, buoyancy, and prolonged drug release. FTIR analysis verified the lack of drug–polymer incompatibility. All formulations demonstrated satisfactory clarity, consistent appearance, and compatibility with gastric pH. Elevated polymer concentration led to enhanced viscosity, gel strength, and regulated medication release. The raft gels exhibited swift floating (lag time 28–42 seconds) and maintained buoyancy for more than 12 hours. The drug content varied between 97.54% and 99.12%. In vitro release demonstrated sustained delivery for up to 8 hours, with VR3 exhibiting best efficacy. The release kinetics adhered to first-order and Higuchi models, exhibiting non-Fickian diffusion. Accelerated stability experiments of VR3 validated the formulation's stability. The optimised raft gel presents a promising gastro retentive method for enhancing valsartan therapy.