3D printed capsules for quantitative regional absorption studies in the GI tract

Abstract

Drug development is a long process which requires careful evaluation of the drug substance (active pharmaceutical ingredient, API), drug product (tablet, capsule etc.) and the bioperformance (both pre-clinical and clinical) before testing the efficacy of the final dosage form. The earliest assessment of a new drug substance requires an understanding of the safety and clinical performance (Phase 1) wherein faster processes (like on-site formulation strategy) have been set in place for quick clinical read-outs. One key gap that exists in this early assessment is the ability to evaluate modified release drug products. Here, an additive manufacturing approach is used to prepare polyvinyl alcohol (PVA) capsule shells using 3D printing (3DP), where the shells can be filled with either a solid or a liquid vehicle containing the API. In this work we demonstrate how we can delay the release of the API from the printed capsules allowing us to evaluate regional absorption in pre-clinical studies. By using 3DP, a new method to provide a series of release profiles is demonstrated, where the induction time of a delayed burst release is controlled by the wall thicknesses of printed capsules. New hanging baskets were also designed and 3D printed for the dissolution tests to better understand the rupturing of these capsules in an USP 2 dissolution apparatus. By controlling the wall thickness of the capsule, the induction time of drug release can be controlled from 12 to 198 min. This wide range of induction times demonstrated with this 3DP strategy is not currently available in a commercially available oral drug product form. Varying the induction times to the drug release to interrogate different regions of the GI tract is exhibited in vivo (beagle dogs) and initial analysis suggested a good in vitro/in vivo relationship (IVIVR).