Coating is a proceeding to cover tablet with a layer / substances.

The purpose of tablet coating:
1. Cover the unpleasant taste, odor and color
2. Physical and chemical protection in medicine from environment (light, moisture, and air)
3. Control of drug release as in enteric coating or sustained release
4. Improve the appearance of tablets
5. Assist and facilitate the identification of drug
6. Easing the process of blistering

Various kinds of tablet coating

1. Sugar Coated Tablets (SCT)
Have you ever take medicine that taste sweet? it because bitter medicine has been coated with sugar-coated so that the bitter taste is reduced or offset. Suitable also for drugs that smells fishy or unpleasant smell. Usually, because of the coating, absorbs process becomes slower. Sugar Coated tablets are usually used for children.

Sugar Coated Tablet involves successive application of sucrose-based coating formulations to tablet cores, in suitable coating equipment. Water evaporates from the syrup leaving a thick sugar layer around each tablet. Sugar coats are often shiny and highly colored.

2. Film Coated Tablet (FCT)
This type of coating is the most widely used. The point is to beautify the tablets with a variety of colors, protect the tablet to remain stable and cover up a bad taste. Drugs that not attractive in colors such as the herbal extract or uneven color could be covered. Not all drugs need to be coat. There are still shows its original color, or added color at the time of mixing, before compressing.

Film Coated Tablet involves the deposition, usually by spraying method, of a thin uniform film of a polymer formulation surrounding a tablet.

3. Enteric Coated Tablet (ECT)
For certain drugs, sometimes the best absorption is not in gastric but in intestines, such as Zantac (ranitidine 300mg) and Eflagen (Diclofenac Sodium). This drug must be absorbed in the small intestine, that’s why tablets need to be coated to withstand the stomach acid so that when tablet reach the small intestine, the drug released slowly. Therefore, this drug should never be crushed or chewed, because when refined form of drugs into the particles with a surface area that reacts with stomach acid more and more, of course reduce / damaging effects of the drug.

4. Compression Coating
Although less popular, it gained increased interest in the recent years for creating modified-release products. It involves the compaction of granular materials around a preformed tablet core using specially designed tableting equipment. Compression coating is a dry process.

Read More :  Compression Coating Tablet

5. Gelatin coated tablet
The innovator product, the gelacap, is a capsule shaped compressed tablet coated with gelatin layer.