Choosing the right in vitro test for a novel gastroretentive dosage form is one of the hardest tasks during the development of these systems. The major drawback of many in vitro tests is their low predictive value. For instance, a gastroretentive system based on flotation on top of gastric contents is often tested in a glass of water which certainly does not display the in vivo conditions. Within this context, the floating time and floating lag time are important parameters. However, the main hurdle for gastroretentive systems remains the gastric peristalsis and the induced transport to the duodenum.
Our in vitro system, the mechanical antrum model, can simulate these contraction waves. It consists of a central elastic silicone tube which complies with the antral dimensions. The tube is surrounded by an inflatable ring-shaped balloon which can expand to its center. Inflation results in a local occlusion inside the silicone tube. The balloon is mounted into a movable plate which is controlled via a stepping motor. Herby, the occlusion can be moved forward or backward at desired velocity, mimicking the propagation of an antral contraction wave. The occlusion diameter can be varied by applying different pressures via compressed air supply. By use of this novel in vitro model we are able to characterize the intragastric transport behavior and thus the gastroretentive potential of dosage forms in early stages of drug development.
M. Neumann, F. Schneider, M. Koziolek, G. Garbacz, W. Weitschies. A novel mechanical antrum model for the prediction of the gastroretentive potential of dosage forms. Int. J. Pharm. 530 (2017) 63-70
F. Schneider, M. Hoppe, M. Koziolek, W. Weitschies. Influence of Postprandial Intragastric Pressures on Drug Release from Gastroretentive Dosage Forms. AAPS PharmSciTech 19 (2018) 2843-2850