Filling, Binding, Stabilizing and Coating Materials

In conventional tabletting, powder particles are made to adhere with binding materials (granulation). Generally, the solutions of natural, semi-synthetic, or synthetic polymers are used for granulation (solutions of gelatine, cellulose ethers, and polyvinyl alcohol). 

Macromolecular colloid solutions also play an important role in ensuring the stability of disperse systems (e.g. suspensions, emulsions). In the case of emulsions the polymer decreases the rate of separation by increasing viscosity on the one hand, and it has an enthalpy stabilizing effect by adsorption on the surface of the droplets on the other hand [3, 4, 7]. Depending on the concentration of the polymer, a protecting and flocculating effect can be observed during the interaction between suspensions and polymers. If the polymer concentration is low, the polymer adsorbed on the surface of the particles connects the particles into loose floccules. Thereby, the rate of 

The solutions of pol)miers are also used for coating tablets. Coating may have the following purposes i) to mask the unpleasant taste of the active sul stance, ii) to protect the active substance against external effects, iii) to give the product a pleasant look, and iv) to ensure controlled drug release. (The latter is going to be discussed in Chapter 16.4.2.) 

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