Next generation capsules: emerging technologies in capsule fabrication and targeted oral drug delivery

Capsule-based drug delivery has undergone significant advancements, offering enhanced protection for active pharmaceutical ingredients (APIs) and enabling precise, site-specific release in the gastrointestinal (GI) tract. Recent innovations such as enteric coatings, dual-layer encapsulation (double-dipping), and advanced polymer formulations have expanded the functional capabilities of capsules, offering opportunities to enhance bioavailability and stability of sensitive molecules like peptides, proteins, and RNA-based therapies. Additionally, cutting-edge manufacturing techniques-including injection molding and 3D printing-are facilitating the production of customized capsules with controlled release profiles, thereby minimizing systemic side effects and enhancing patient adherence. This review examines the technological advancements from single-layer to double-layer capsules, a crucial development to achieve enteric properties and enhance drug protection against degradation in gastric fluids. We explore key capsule manufacturing technologies, including double-dipping, enteric coating, and emerging approaches such as 3D printing and injection molding, which offer new possibilities for precise drug delivery and formulation flexibility. By integrating these advancements, capsule technology continues to evolve as a promising platform for personalized and targeted oral drug delivery. Future research will focus on overcoming production constraints and further refining capsule design to optimize therapeutic efficacy across a broader range of gastrointestinal and systemic diseases.