Film coating is a process in which a thin layer of polymer, pigments, or other materials is applied to the surface of a pharmaceutical tablet. This protective layer enhances the tablet’s appearance, masks unpleasant tastes, and improves handling while maintaining the core’s disintegration and drug release properties. Compared to traditional sugar coating, film coating results in minimal weight gain, typically only 2–3%.
1.2 Explanation of the General Process
The film coating process involves placing tablets in a rotating drum where heated air circulates to warm the tablets. A solution or suspension of the coating material is sprayed as fine droplets onto the tablet bed. The droplets spread and form a thin film, while the solvent evaporates, leaving a uniform coating. This process allows for embossing and consistent coating thickness without affecting the tablet’s efficacy.
Minimal weight increase (2–3% vs. 60–80% for sugar coating)
Faster and easier production
Better tablet shape retention and embossing capability
Easier automation for GMP compliance
2. Organic Film Coating
2.1 What is Organic Film Coating
Organic film coating uses volatile organic solvents instead of water to form the coating film. Common solvents include alcohols, esters, and chlorinated hydrocarbons. Due to the high volatility of these solvents, solvent film coatings dry rapidly and are suitable for moisture-sensitive tablets.
2.2 Advantages of Organic Film Coating
Faster drying time due to high solvent volatility
Can be applied to moisture-sensitive formulations
Reduces tablet exposure time in the drum, minimizing mechanical stress
2.3 Disadvantages of Organic Film Coating
High environmental and safety requirements due to flammable solvents
Production area may need ventilation modifications
Waste solvent disposal is the responsibility of the manufacturer
Possible impact on taste and smell of the tablet
Higher equipment and installation costs
3. Aqueous Film Coating
3.1 What is Aqueous Film Coating
Aqueous film coating uses water as the solvent for the coating solution. It is the most common film coating process due to its safety, non-toxicity, and reduced environmental impact.
3.2 Advantages of Aqueous Film Coating
Safe and non-toxic process
Easier environmental compliance; excess water can be safely released
No solvent residues that may affect taste or smell
Simplified equipment requirements compared to organic coating
3.3 Disadvantages of Aqueous Film Coating
Slower drying due to lower volatility of water
Tablets remain in the drum longer, potentially causing mechanical stress
Increased energy consumption for drying
4. Key Differences Between Organic and Aqueous Film Coating
Feature
Organic Film Coating
Aqueous Film Coating
Drying Time
Fast, due to volatile organic solvents
Slower, requires longer drying due to water
Environmental & Safety Impact
Higher risk, requires ventilation and strict safety protocols
Low risk, non-toxic, environmentally friendly
Production Costs
Higher, due to equipment modifications and solvent handling
Moderate, may require more energy for drying
Equipment Requirements
Specialized, explosion-proof, and ventilated equipment needed
Standard film coating equipment sufficient
Suitability for Moisture-Sensitive Products
Excellent
Limited
Impact on Taste & Smell
Possible residual solvent smell/taste
Minimal, does not affect taste or smell
4.1 Drying Time
Organic coatings dry faster due to volatile solvents, while aqueous coatings require longer drying time because of water evaporation.
4.2 Environmental and Safety Impact
Aqueous film coating is safer and environmentally friendly. Organic coatings require strict safety protocols, ventilation, and solvent waste disposal.
4.3 Production Costs
Organic coating generally has higher production and installation costs due to equipment modifications and solvent handling. Aqueous coating is more cost-effective but may incur higher energy costs for extended drying.
4.4 Equipment Requirements
Organic film coating often requires specialized ventilation and explosion-proof equipment. Aqueous coating can typically be performed with standard film coating process equipment.
5. Conclusion
Both organic and aqueous film coating methods have their unique advantages and limitations. Organic film coatings are ideal for moisture-sensitive products and faster production, while aqueous coatings offer a safer, environmentally friendly, and cost-effective alternative. Understanding the differences between these film coating processes allows pharmaceutical manufacturers to choose the method best suited for their product requirements.
Skip to content 
EN 
RU 
KO 
JA 
TR 
ZH 
TH 
PT 
FR 
ES