1. What is tablet coating?

Tablet coating is the process of applying a thin layer of coating material to a tablet’s surface to protect it, improve its appearance, or modify its drug release profile.

2. What are the main types of tablet coatings?

1. Sugar coating – Improves taste and appearance.
2. Film coating – Provides protection and controls drug release.
3. Enteric coating – Protects the tablet from stomach acid and ensures release in the intestines.

3. What materials are used in film coating?

Film coating typically uses:

• Polymers (e.g., HPMC, PVA)
• Plasticizers (e.g., PEG, glycerin)
• Colorants (e.g., titanium dioxide)
• Solvents (e.g., water or organic solvents).

4. Why is enteric coating important?

Enteric coating protects acid-sensitive drugs from degradation in the stomach and ensures they release in the intestines, where the environment is less acidic.

5. What are the key parameters to monitor during tablet coating?

• Inlet and outlet air temperature
• Spray rate
• Atomization pressure
• Tablet bed temperature
• Pan speed

6. What is the purpose of using plasticizers in tablet coating?

Plasticizers improve the flexibility and elasticity of the coating film, preventing cracks and ensuring uniform coverage.

7. What are common coating defects and their causes?

1. Picking and sticking – Over wetting or high spray rate.
2. Orange peel effect – High atomization pressure or low spray rate.
3. Chipping – Low plasticizer content or poor adhesion.
4. Color variation – Uneven mixing or spraying.

8. What is the significance of spray rate in tablet coating?

The spray rate controls the application of the coating solution. Too high a spray rate can lead to overwetting, while too low can cause uneven coating.

9. What are the advantages of film coating over sugar coating?

• Faster process
• Requires less material
• Provides better protection
• Allows controlled drug release

10. How is the quality of a coated tablet evaluated?

The quality is assessed using:

• Appearance – Smooth and uniform coating.
• Weight gain – Indicates the thickness of the coating.
• Disintegration/dissolution test – Ensures functionality.

11. What is the role of atomization pressure in the coating process?

Atomization pressure breaks the coating solution into fine droplets, ensuring uniform application on the tablets.

12. How does pan speed affect the coating process?

Pan speed ensures proper mixing and exposure of tablets to the spray. If it’s too slow, coating may be uneven; too fast, tablets may break.

13. What is aqueous coating, and why is it preferred?

Aqueous coating uses water as a solvent instead of organic solvents. It is safer, environmentally friendly, and cost-effective.

14. What are sustained-release coatings?

Sustained-release coatings control the drug release rate, allowing for a gradual release over an extended period.

15. What factors influence the drying efficiency in tablet coating?

Drying efficiency depends on:

• Inlet air temperature
• Airflow rate
• Humidity levels
• Tablet bed temperature