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3. Compression coating
4. Enteric coating
5. Sustained release coating

1. Sugar Coating:
It consists of several sequential steps applied in traditional coating pans.
Steps:

1. Sealing: protect tablet core from moisture by applying shellac or polymer in organic
solvent.

2. Sub-coating: builds up size using gelatin or acacia with sugar and calcium carbonate.
3. Smoothing: smooth surface by applying syrup solution.
4. Coloring: color syrup added to obtain desired shade.
5. Polishing: with waxes such as beeswax, carnauba wax for gloss.

Disadvantages of sugar coating:
• Tedious and time-consuming (may take hours).
• Needs skilled operator.
• Increases tablet weight by up to 50%.

2. Film coating:
A single, thin, continuous film (10–20 µm) is formed around each tablet using polymeric
solution or dispersion.
Advantages:

• Shorter process time.
• Weight increase only 2–3%.
• More reproducible and automated.
Film coating composition:
• Film-forming polymer: HPMC, HPC, EC, CAP, PVAP, acrylic polymers (Eudragit).
• Plasticizer: PEG 400, glycerin, propylene glycol, castor oil.
• Colorant: Titanium dioxide, lake pigments.
• Solvent: Water, ethanol, isopropanol or mixtures.

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