Filament-based bezoar structures as a pathophysiological inspired concept for gastroretentive drug delivery: Integration of material design and biorelevant mechanical in vitro testing.

Abstract

Achieving reliable gastric retention remains one of the key unsolved challenges in oral drug delivery. Conventional gastroretentive approaches - such as floating, expanding, or mucoadhesive systems - often fail to withstand the complex mechanical forces of the stomach, leading to inconsistent residence times and unpredictable drug release, especially in the fasting state. Inspired by the natural persistence of trichobezoars, this work introduces filament-based "bezoar-like" structures as a novel, pathophysiological inspired concept for gastroretentive drug delivery. Multifilament polymer fibers were produced by hot-melt extrusion and assembled into spherical bezoars capable of resisting peristaltic propulsion while allowing controlled drug release. To capture the interplay between material properties and gastric motility, a comprehensive in vitro framework was established combining texture analysis, a modified antrum model, and stress-based dissolution testing. These methods reproduce physiologically relevant compression, shear, and retropulsion events that are absent from conventional compendial apparatuses. The study demonstrates that integrating structural design with biorelevant mechanical testing enables more realistic assessment of gastroretentive performance. The proposed filament-based systems mimic key viscoelastic features of natural hair-like bezoars and withstand simulated gastric motility while maintaining sustained release characteristics. This concept provides a new paradigm for designing robust gastroretentive dosage forms and highlights the need for mechanical stress-adapted in vitro methods as a prerequisite for meaningful in vivo translation.

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