This book introduced novel starch-based thermoplastic capsules (S-PVA-Cs) and demonstrated their advantage over SGCs with respect to hydrophilic lipid-based formulations. Release studies in biorelevant media revealed differences in how formulations hydrated and interacted with the shell material. Drug-excipient-shell interactions were observed in various capsule types (SGCs, S-PVA-Cs, and VegaGels®) at different levels of biopharmaceutical in vitro testing. A better mechanistic understanding was attained that may guide future development of soft capsule products.