Film coating

Film coating is a process used in pharmaceutical industry to cover tablets, capsules, or other solid dosage forms with a thin layer of edible material. This process is used to mask the taste, odor, or color of the drug, to protect the drug from the environment, to control the release of the drug, and to improve the appearance of the tablet.

Process

Film coating involves the application of a thin, uniform layer of a film-forming material to the surface of a dosage form. The film-forming material is usually a polymer, and the process is carried out in a coating pan or a fluidized bed coater. The coating solution is sprayed onto the rotating tablets, and the solvent is evaporated by heating. The process continues until the desired film thickness is achieved.

Materials

The film-forming materials used in film coating are usually polymers such as hydroxypropyl methylcellulose (HPMC), polyvinyl alcohol (PVA), and ethyl cellulose. These polymers are soluble in water or organic solvents, and they form a film when the solvent is evaporated. Other ingredients such as plasticizers, pigments, and opacifiers may be added to the coating solution to modify the properties of the film.

Advantages

Film coating has several advantages over other coating methods such as sugar coating and enteric coating. Film coating is a faster and more efficient process, and it results in a thinner and more uniform coating. Film coating also allows for better control of the release of the drug from the dosage form.

Disadvantages

The main disadvantage of film coating is that it requires specialized equipment and skilled operators. The process is also sensitive to changes in the coating solution and the operating conditions, which can affect the quality of the coating.

See also

• Tablet (pharmacy)
• Capsule (pharmacy)
• Pharmaceutical formulation
• Controlled release

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