What defines a capsule in terms of drug form?

A capsule is specifically defined as a form of medication where powdered or solid substances are enclosed within a gelatin shell. This design serves multiple purposes: it protects the contents from environmental factors, masks unpleasant tastes, and facilitates the controlled release of the medication upon ingestion. The gelatin shell can be hard or soft and is designed to dissolve in the gastrointestinal tract, allowing for the active ingredients to be absorbed by the body efficiently.

The characteristics of capsules make them unique compared to other drug forms. For example, while some medications may be solid and dissolve in the stomach, not all are contained within a gelatin shell. Similarly, liquid medications are not considered capsules, nor are small particles mixed with liquids. Therefore, the definition focusing on a powdered or solid medication enclosed specifically in gelatin is what accurately describes a capsule in pharmacology.