What type of capsule features a flexible, plasticized shell commonly plasticized by glycerin?

The type of capsule that features a flexible, plasticized shell, typically plasticized by glycerin, is the soft gelatin capsule. These capsules are distinct from hard gelatin capsules due to their formulation and intended use. Soft gelatin capsules are designed to be hermetically sealed and can accommodate liquid formulations, pastes, or dry powders.

The plasticization achieved through the addition of glycerin gives the soft gelatin capsule its characteristic flexibility and allows for the encapsulation of more complex formulations, such as oil-based or hydrophobic substances. This flexibility is essential for providing a smooth ingestion experience and helps in preventing the capsule from breaking or becoming brittle.

In contrast, hard gelatin capsules consist of two rigid shells that are not plasticized, making them more suitable for solid formulations like powders and granules. Enteric-coated capsules are designed to dissolve in the intestines rather than the stomach, thus providing a coating that resists gastric acid. Liquid capsules also refer to specific capsule formulations generally made from gelatin or other materials, but they aren't primarily characterized by flexibility derived from plasticization.

Overall, the unique properties of soft gelatin capsules, particularly the use of glycerin for plasticization, distinguish them from other capsule types and make them a preferred option for specific pharmaceutical applications.