Optimized Magnetically Docked Ingestible Capsules for Non-Invasive Refilling of Implantable Devices

Abstract

Automated drug delivery systems (ADDS) improve chronic disease management by enhancing adherence and reducing patient burden, particularly in conditions like type 1 diabetes, through intraperitoneal insulin delivery. However, periodic invasive refilling of the reservoir is needed in such a class of implantable devices. In previous work, an implantable ADDS with a capsule docking system is introduced for non-invasive reservoir refilling. Yet, it encounters reliability issues in manufacturing, sealing, and docking design and lacks evidence on intestinal tissue compression effects and chronic in vivo data. This work proposes an optimization of the different components featuring this ADDS. The ingestible capsule is designed, developed, and tested following ISO 13485, exhibiting high insulin stability and optimal sealing for six days in harsh gastrointestinal-like conditions. A magnetic docking system is optimized, ensuring reliable and stable capsule docking at a clinically relevant distance of 5.92 mm. Histological tests on human intestinal tissues confirm safe capsule compression during docking. Bench tests demonstrate that the integrated mechatronic system effectively docks capsules at various peristalsis-mimicking velocities. A six-week in vivo test on porcine models demonstrates chronic safety and provides hints on fibrotic reactions. These results pave the way for the further evolution of implantable ADDS.