As a product of the industrial age, capsules have the advantage of masking taste and improving drug stability. The medicine is put into the capsule shell, which can isolate the medicine from the outside world, reduce the influence of air, light, and moisture, and has a certain shielding, protection, and stabilization effect on the medicine with bad smell and instability.

    Compared with tablets and pills, drugs are filled in capsules with powder or granules, and the preparation process is not affected by factors such as mechanical pressure, and the drugs can be rapidly dispersed, dissolved, and absorbed in the gastrointestinal tract.

    Liquid medicines or medicines with high oil content can be filled into soft capsules to make solid preparations, which are convenient to take and carry.

    Capsules can be subdivided into hard capsules, soft capsules (pellets), sustained-release capsules, controlled-release capsules, and enteric-coated capsules.

    (1) Hard capsules (capsules): refers to the uniform powders, granules, small tablets, pellets, semi-solids or liquids, etc., made of drugs or suitable auxiliary materials, and filled into hollow capsules by appropriate preparation technology.

    (2) Soft capsule: refers to the direct encapsulation of a certain amount of liquid drug substances, or the preparation of solutions, suspensions, emulsions, or semi-solids by dissolving or dispersing solid drug substances in suitable excipients, and sealing them in soft capsules. capsules in the material. Soft capsules, also known as capsules, can be prepared by the drop method or compression method.

    (3) Sustained-release capsules: refers to capsules that slowly and non-constantly release drugs in a prescribed release medium.

    (4) Controlled-release capsules refer to capsules that release drugs slowly and at a constant rate in a specified release medium.

    (5) Enteric-coated capsules refer to hard capsules prepared by filling capsules with granules or pellets coated with enteric-coated materials, or hard or soft capsules prepared with suitable enteric-coated materials.