Capsule excipients refer to the substances that are added to a capsule formulation along with the active pharmaceutical ingredient to enhance their properties, stability, and bioavailability. The primary function of these excipients is to provide the necessary mechanical and physicochemical properties for manufacturing the capsule or tablet.
Some common capsule excipients include:
1. Diluents or fillers: These are added to increase the bulk of the formulation, enhance the flow properties, and provide uniformity of dosage. Examples include microcrystalline cellulose, lactose, and starch.
2. Lubricants: These are used to prevent sticking of the formulation to the machinery during manufacturing and facilitate easier release from the capsule. Examples include magnesium stearate, stearic acid, and talc.
3. Binders: These are added to help hold the formulation together and maintain the integrity of the capsule. Examples include hydroxypropyl cellulose, cellulose derivatives, and polyvinylpyrrolidone.
4. Disintegrants: These are added to promote the rapid release of the active ingredient in the body. Examples include croscarmellose sodium, sodium starch glycolate, and cross-linked polyvinylpyrrolidone.
5. Colorants: These are used to enhance the appearance of the capsule and improve patient compliance. Examples include titanium dioxide, iron oxide, and FD&C dyes.
6. Flavors and sweeteners: These are added to improve the palatability of the formulation and mask any unpleasant taste of the active ingredient. Examples include artificial and natural flavors, as well as sweeteners such as sucrose and aspartame.
The selection and amount of capsule excipients are critical to ensure the safety, efficacy, and stability of the final product. These excipients should be carefully chosen based on their intended use and compatibility with the active ingredient. Additionally, they must meet the appropriate regulatory standards and be appropriately labelled on the product.