Capsules

Capsule is a small, container-like dosage form used to enclose a pharmaceutical substance for oral administration. The two major forms are hard capsules, which consist of two separate pieces—a cap and a body—and soft gelatin capsules, which are a single, flexible shell that is hermetically sealed around the fill. Capsule shells are typically made from gelatin, but plant-based alternatives exist, including hydroxypropyl methylcellulose (HPMC), pullulan, and starch derivatives to produce vegetarian or vegan capsules. Contents can be powders, pellets, liquids, or pastes, and may include active ingredients with excipients to aid flow, stability, and taste masking.

Manufacture and filling involve distinct processes. Hard capsules are produced as two-piece shells on dipping machines, dried, then filled with the chosen dose and joined. Soft capsules are formed from a gelatin film around a liquid or semi-solid fill in a rotary die process, then sealed and dried. Fill materials vary from simple powders to complex suspensions or oils. Packaging often includes desiccants, and moisture content is controlled to maintain shell integrity. Some capsules are designed for targeted release, such as enteric-coated or time-release variants.

Regulatory oversight governs identity, strength, quality, and safety. Capsules must meet disintegration and dissolution criteria to ensure release of the contents in the gastrointestinal tract. Storage typically requires cool, dry conditions to maintain shell integrity and fill stability. Capsules offer advantages such as precise dosing, taste masking, and ease of swallowing, but may pose moisture sensitivity and compatibility considerations with certain ingredients.