Film Coatings of Solid Dosage Forms

Coating tablets with a thin polymeric film is commonly performed to modify drug release, mask the taste of therapeutic agents, to enhance the stability of the drug within gastrointestinal fluids or may be used for purely aesthetic reasons. The film is usually 10-100 im thick and is compo.sed of at least one polymer, a plasticiser and, when required, other minor additives such as colorants and opacifiers. 

The use of polymer coatings for the controlled relea.se of drugs is described in more detail in a later section of the review. 

Various. synthetic and natural hydrophilic polymers are extensively used to enhance the physical stability of pharmaceutical disperse. systems. Examples of these include alginates, carrageenan and xanthan gum, whereas a wide range of synthetic polymers has also been used for this purpose, e.g., cellulose ethers, polyfacrylic acid), PVP and PVA. 

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