Types and Functionality of Tablet Coating

Tablet coating is the outer covering of a tablet with a layer/substance. The coats used range from the traditional sugar coating to the present polymer and polysaccharides based coats.
The types of coats depending on the specific functionality of the tablet as well as the target consumer of the tablet.

Types of Tablet Coating
1. Sugar Coated Tablets
2. Film Coated Tablets
3. Gelatin Coated Tablets
4. Enteric Coated Tablets
5. Compression Coating Tablets
6. Other Types

The types of tablet coating used to go to enhance specific functionality that ranges from obscuring bitter taste of the tablets, creating a smooth covering to promote easy swallowing, protect the pill from damage or external forces, create a branded pill for marketing purposes as well as increase the shelf life of the tablets.

1. Sugar Coated Tablets

Have you ever chewed on a tablet and had an explosion of bitter regret in your mouth? This type of covering offers a sweet coat mainly made from polysaccharides and sucrose to obscure the bitter taste of the tablet. The sugar coating also offers a sweet aroma especially on foul smelling pills like fish supplements.
The sugar syrup is coated on the tablet and water is left to evaporate from the syrup leaving a sugar coating. The coating results in a highly flavored and shiny tablet.
Functionality:
A. Especially used for kids.

2. Film Coated Tablets

This is the most commonly used coating in the pharmaceutical industry today. The coating is used for aesthetic purposes and to improve the taste of the pill. Tablets especially those from herbal extracts are not visually pleasing, therefore a coating is necessary for beautifying the tablet using different colors. In other cases, not all tablets need a coat, just a film to maintain its original color.
Spraying is used to create an even film around a tablet.
Functionality:
A. Creates a stable and strong tablet.
B. Tablet branding colors and identifiable coatings.

3. Gelatin Coated Tablets

Have you ever had Jell-O? If you have that's gelatin. Gelatin is a type of protein that is derived from partial hydrolysis of collagen. It is found from animal parts and contains amino acids that are the 'building blocks' of proteins.
Gelatin is used to create the gelcap, a capsule-shaped tablet as the outer covering.
Functionality:
A. Creates a rich protein-based coating.

4. Enteric Coated Tablets

This coating provides a stomach acid resistant coat for the tablets that have an ingredient that is sensitive to acid. If a tablet is to be absorbed in the small intestines, therefore there is need for the tablet to withstand stomach acid and reach the targeted area where it is absorbed slowly where there is no acidity.
This type of tablet should not be crushed or chewed to prevent the risk of damage due to a reaction with stomach acid.
Functionality:
A. Deliver the tablet to intestines without damaging effects to the drug or consumer.

5. Compression Coating Tablets

It involves compaction of granular particles around a preformed tablet using special equipment through a dry process. It is less common than the rest and consist of the outer covering and an internal core.
Functionality:
A. The delayed release of tablet especially those for intestines.

6. Other Types

These are the technologies or the methods of application of the coats that sometimes are categorized as types of tablet coating.
A. Electrostatic Coating
Uses a strong electrostatic charge applied to the substrate and a coat of opposite charge is applied to the substrate through spraying.
B. Dip Coating
The tablet is immersed in the coating fluid.
C. Rotary-Die Coating
A rotary die process is used to prepare soft gelatin capsules.