3 Types of Pharmaceutical Coating: Sugar, Film, and Enteric

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What are the types of coating?

Pharmaceutical coatings are a fundamental part of drug development and manufacturing, offering multiple advantages such as protection, taste masking, and controlled drug release. 

These coatings help ensure that medications are not only effective but also patient-friendly. The coating process involves applying a thin layer of a protective substance over the surface of tablets, capsules, or granules. 

Pharmaceutical coatings not only enhance the drug’s appearance but also improve its stability and performance. 

In this article, we’ll explore the concept of pharmaceutical coating, and dive deep into the different types: sugar coating, film coating, and enteric coating.

Pharmaceutical Coating
Pharmaceutical Coating
Pharmaceutical Coating

What is Pharmaceutical Coating?

What is Pharmaceutical Coating

What is pharmaceutical coating? Pharmaceutical coating is the process of applying a thin film of material to a solid dosage form. These coatings are typically polymers or sugar-based solutions that serve various purposes depending on their formulation. 

The coatings can be protective, functional, or decorative. Whether it’s masking an unpleasant taste, controlling the rate of drug release, or protecting sensitive ingredients from environmental factors, pharmaceutical coatings are vital for enhancing both drug efficacy and patient compliance.

The choice of coating depends on several factors, including the active pharmaceutical ingredient (API), the drug’s required release profile, and the manufacturing process itself. 

Coatings also play a key role in meeting the regulatory requirements for drug safety and efficacy. As drug delivery systems evolve, so too does the complexity and capability of pharmaceutical coatings.

Now, let’s look at the main types of coating commonly used in the industry.

Types of Coating

What are the different types of coating? The different types of coating are sugar coating, film coating, and enteric coating.

Sugar Coating

Sugar Coating

What is sugar coating? Sugar coating is one of the oldest and most traditional methods used in pharmaceutical manufacturing. This process involves the application of several layers of sugar-based syrups to the tablet’s surface. 

These layers are applied in multiple stages, each serving a different function—starting from sealing the core of the tablet to applying a smooth and shiny final layer. The result is a glossy, polished tablet with a sugar-based outer layer.

  • Suitability

Sugar coating is particularly suited for masking the unpleasant taste or odor of certain medications. By covering the tablet in a sugar layer, the process significantly improves the palatability of the drug, especially for children. This coating method also adds aesthetic value to the tablets, making them more visually appealing and easier to differentiate.

The downside, however, is that sugar coating increases the size and weight of the tablet. As a result, this method is less suited for modern formulations where tablet size must be kept small for ease of swallowing. 

The process itself is also labor-intensive and time-consuming, requiring multiple layers to achieve the final product. For these reasons, sugar coating has largely been replaced by more efficient techniques like film coating.

Despite these limitations, sugar coating is still used today in cases where taste masking is crucial, and the additional size of the tablet is not a significant issue.

  • Stages of Sugar Coating
  1. Sealing: Protects the tablet core from moisture.
  2. Subcoating: Builds up the tablet size and rounds the edges.
  3. Smoothing: Achieves a smooth surface for the color coat.
  4. Coloring: Provides the desired color and enhances tablet appearance.
  5. Polishing: Gives the tablet a shiny, glossy finish.

Film Coating

Film Coating

What is film coating? Film coating is the most widely used pharmaceutical coating method today. 

Unlike sugar coating, film coating involves the application of a thin layer of polymer-based film onto the surface of the tablet. This polymer film is usually applied in a single layer using a spray mechanism while the tablets are rotating in a pan. The process is faster and more efficient than sugar coating, and the resulting film is much thinner and more durable.

Film coating offers several advantages, including protection against environmental factors, improved aesthetics, and the ability to modify the drug release profile. The film coating can be transparent or colored, depending on the desired appearance of the tablet.

  • Suitability
    Film coating is suitable for a wide range of pharmaceutical applications, including immediate-release and modified-release tablets. It is often used to:
  • Protect the active ingredients from moisture, light, or oxidation.
  • Mask unpleasant tastes or odors, making the medication more pleasant to take.
  • Improve swallowing ease by providing a smooth surface.
  • Control the release of the active ingredients, such as in extended-release or sustained-release formulations.

One of the biggest advantages of film coating is that it does not significantly increase the size of the tablet, making it ideal for patients who struggle with swallowing large tablets. Film-coated tablets are also more durable and less likely to break or chip during handling or transportation.

  • Stages of Film Coating

The film coating process typically involves three steps:

  1. Preparation of the coating solution: Polymers, plasticizers, and colorants are mixed with solvents.
  2. Application: The coating solution is sprayed onto the tablet while the tablets are tumbled in a pan.
  3. Drying: Heated air is used to quickly dry the film, ensuring it adheres properly and forms a smooth, uniform layer.

Enteric Coating

Enteric Coating

What is enteric coating? Enteric coating is a specialized type of film coating designed to resist the acidic environment of the stomach. This coating allows the tablet to pass through the stomach intact and dissolve in the more neutral pH environment of the small intestine. 

Enteric coatings are often applied to drugs that can cause irritation to the stomach lining or that are unstable in acidic conditions.

The materials used for enteric coatings are pH-sensitive polymers that only dissolve at a higher pH, ensuring that the drug is released in the intestine rather than the stomach.

  • Suitability
    Enteric coating is suitable for drugs that:
  • Need protection from stomach acid: Some medications can be destroyed by the stomach’s acidic environment, rendering them ineffective if not coated with an enteric layer.
  • Need to avoid stomach irritation: Certain drugs, such as aspirin or NSAIDs, can irritate the stomach lining and are often enteric-coated to prevent this.
  • Require controlled release: Enteric coatings can also be used to modify the drug release profile, ensuring that the active ingredient is only released once it reaches the intestine.

Advantages of Enteric Coating:

  • Protects sensitive drugs from the acidic conditions of the stomach.
  • Prevents stomach irritation caused by the drug.
  • Provides a controlled release mechanism for drugs that need to be absorbed in the intestines.

However, the complexity of enteric coating means that it can be more expensive and time-consuming to produce compared to other coating methods.

Enhance Your Coating Process  

Choosing the right pharmaceutical coating method can greatly impact the success of your drug formulation and its acceptance by patients. Whether you’re looking to mask unpleasant tastes with sugar coating, protect and enhance the function of your drug with film coating, or ensure the proper release of your drug in the digestive system with enteric coating, having the right equipment and expertise is essential.

At China Canaan, we provide a range of advanced coating machines tailored to meet your production needs. Our machines offer precision, efficiency, and uniformity, ensuring that each tablet or capsule is perfectly coated every time. 

BGX Series Coating Machine – Interchangeble Coating Pan
LB Centrifugal Granulating & Coating Machine
BGX Series Coating Machine

Contact us today to explore our solutions and enhance your pharmaceutical production line.

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