A next-generation mechanical in vitro antrum model for the evaluation of gastroretentive dosage forms under...

Gastroretentive drug delivery systems aim to prolong gastric residence time, yet their in vivo performance is often inconsistent, largely due to insufficient consideration of mechanically driven gastric emptying. In particular, the role of antral peristalsis in the transport of solid oral dosage forms is underrepresented in current in vitro models. In this study, a next-generation in vitro antrum model was developed to simulate mechanically relevant conditions governing gastric emptying. The system is based on a flexible tubular compartment with mechanically induced peristaltic waves and allows controlled variation of key parameters, including wave velocity (3 mm/s), fluid volume (50-150 mL), inclination (0-40°), and occlusion as residual lumen diameter (1.6-25.6 mm). Using test objects with defined differences in size, density, and deformability, the model demonstrated that transport behavior is primarily governed by the interplay of geometric confinement, deformation, and contact mechanics. Rigid objects were transported once a critical lumen diameter threshold was reached, whereas highly deformable and entangled structures partially resisted peristaltic transport. Observed size-dependent transport behavior was consistent with in vivo findings from relevant literature. The model provides a simple and mechanistically relevant platform for early-stage screening of gastroretentive dosage forms and supports a mechanics-driven understanding of gastroretention.