What are the classifications of capsules?

(1) Hard capsules
1. The composition of empty capsules: Gelatin is the main capsule-forming material of empty capsules, which is made from animal bones and skins. Other capsule materials include starch capsules, methyl cellulose capsules, hypromellose capsules, and sodium alginate capsules. In order to increase the toughness and plasticity of empty capsules, plasticizers are generally added, such as glycerin, sorbitol, CMC-Na, etc.; to reduce fluidity and increase jelly power, thickener agar, etc. can be added; for light-sensitive drugs, A sunscreen agent, such as titanium dioxide, can be added to the capsule shell; food coloring can be added for aesthetics and easy identification; to prevent mildew, preservatives, such as paraben, can be added.
2. Contents: Generally, sucrose, lactose, microcrystalline cellulose, modified starch, silicon dioxide, magnesium stearate, talc, HPC, etc. can be added to improve the fluidity of the drug or avoid delamination.

(2) Soft capsules
1. The composition of the capsule wall: it is composed of gelatin, plasticizer, and water. Plasticizers are glycerin, sorbitol, or a mixture of the two. Compared with hard capsules, the proportion of plasticizer and water in the capsule shell is higher.
2. Contents and additives: Soft capsules can be filled with various oils and solutions, suspensions, semi-solids, or solid components that have no dissolving effect on gelatin. When the content is a solid drug powder, vegetable oil or PEG400 is often used as a dispersion medium to prepare a suspension.