Plant-based enteric-coated capsules: Becoming the mainstream choice for enteric-coated formulations.

In the development of enteric-coated formulations, the capsule shell—a component that was once overlooked—has now evolved into a critical factor influencing drug stability, release accuracy, and consistency of quality. Thanks to advancements in material properties, enteric-coating performance, and manufacturing processes, plant-based (HPMC) enteric-coated capsules are rapidly transitioning from being an alternative option to the preferred choice.

Unlike traditional gelatin capsules derived from animal collagen, plant-based enteric-coated capsules use hydroxypropyl methylcellulose (HPMC) as their core material. HPMC boasts stable chemical properties and a robust molecular structure, which help it avoid interactions with complex drug formulations and functional coating materials, thereby laying a solid foundation for highly stable enteric-coated systems.

In terms of core enteric-coating performance, plant-based capsules outperform gelatin capsules in three key aspects. First, their surface characteristics enable stronger affinity with enteric-coating materials such as acrylic resins, ensuring a uniform and robust coating—especially at the junction between the capsule body and cap—thereby preventing premature drug release in the stomach. Second, the stability of HPMC allows it to be compatible with both aqueous and organic solvent-based coating processes, expanding the design possibilities for sustained-release, targeted, and pH-dependent formulations. Third, industry data show that plant-based capsules exhibit virtually zero leakage in simulated gastric acid environments, whereas gelatin capsules have a leakage rate as high as 10%. This is particularly critical for acid-sensitive drugs.

From a manufacturing perspective, plant-based capsules employ an enteric-coating formulation combined with a secondary impregnation molding technique. This approach offers a wider process window and better reproducibility, meeting GMP requirements for stability and traceability. In contrast, some gelatin capsules require cross-linking processes such as formaldehyde treatment, which increase process complexity and pose greater quality risks.

Thanks to their reliable enteric-coating performance, strong process compatibility, and stable quality control, plant-based enteric-coated capsules meet the industry’s demands for safety, stability, and sustainable supply, thereby solidifying their position as the mainstream choice for next-generation enteric-coated formulations.