Formulation and Evaluation of pH-Responsive Natural Polymer Raft Gel of Dexlansoprazole for Gastric Ulcer Protection and Sustained Release

Abstract

The present work was designed to develop and evaluate a pH-responsive natural polymer raft-forming oral gel of dexlansoprazole using sodium alginate and pectin. Eight formulations, DRG1-DRG8, were prepared by adjusting the polymer concentrations while keeping the remaining formulation components constant. Preformulation testing confirmed the identity of the drug, its compatibility with selected excipients and the suitability of the analytical method. The formulations were evaluated for appearance, pH, viscosity, gelation time, floating behaviour, raft characteristics, drug content, in vitro release, release kinetics and stability. An increase in polymer concentration improved viscosity, raft strength and floating duration, but it also reduced pourability and slowed drug release. DRG5 produced the most balanced performance, with viscosity of 2260 ± 113 cP, gelation time of 25 ± 1 s, floating lag time of 30 ± 2 s, raft strength of 12.8 ± 0.6 g, drug content of 99.2 ± 0.9% and 88.4% release within 12 h. The optimized formulation remained stable for three months under accelerated storage. On this basis, DRG5 was selected as the optimized raft-forming system for sustained oral delivery of acid-protected dexlansoprazole.