capsule

A capsule is medicine packed inside a little dissolvable shell, like a tiny edible container. Instead of compressing the drug into a hard brick, you simply pour the powder, granules or liquid into a shell that the body's fluids then melt or soften, releasing the contents.

The shell is usually made of gelatin (from animal collagen) or a plant-based polymer such as hydroxypropyl methylcellulose. Capsules come in two main styles: a two-piece hard capsule that snaps shut around a powder fill, and a one-piece soft capsule sealed around a liquid or oil. Capsules are handy for drugs that taste bad, are hard to compress, or work best dissolved in oil, and the smooth shell is often easier to swallow than a tablet.

Drawbacks include higher cost than tablets, sensitivity of gelatin to humidity and heat, and the fact that the shell can be pulled apart, which is a concern for abuse-prone drugs. Some patients also avoid animal-derived gelatin for dietary or religious reasons, which is why plant-based shells exist.