Learning Objective

• Definition of tablet coating and their types
• Need for tablet coating and its methodology

It is a process of application of coating material onto the external surface of the core tablet. The tablets are coated for the following reasons:

1. To increase aesthetic appeal of the product
2. To mask the unpleasant taste of the drug
3. To protect the drug release in the gastric environment of the stomach with an acid resistant enteric coating material
4. To control or delay the release of the drug for a longer period of time
5. To incorporate another drug in coating
6. To avoid chemical incompatibility
7. To protect the drug from environmental decomposition

Requirements of an uncoated tablet to undergo coating procedure are as follows:

1. The tablet should possess optimum convexity to overcome the problem of edge coverage of the coat.
2. The tablet should be hard enough to withstand the rigors of coating procedure.
3. Tablets should have minimum tendency to absorb the solvent deep into the coat.
4. Friability value of the tablets should be minimum.
5. Tablets should disintegrate immediately once coating has dissolved.
6. Uncoated tablets should be in a position to subject itself to dedusting procedures. Otherwise it may impart roughness on the coated tablets.