Coated tablets are a popular and widely used form of oral medication that offers many advantages to patients and healthcare providers. These tablets consist of a compressed powder or granule of an active pharmaceutical ingredient and other excipients such as binders, fillers and disintegrants. These tablets are then coated with a thin layer of coating material, which can be a polymer, sugar or cellulose derivative.

Protheragen-ING provides specialized development services for coated tablets, helping clients to encapsulate the active pharmaceutical ingredient (API) in an outer covering that improves taste, delays release or protects the pharmaceutical ingredient. Our team consists of experienced drug development specialists and engineers with in-depth knowledge and expertise in coating technology, drug formulation and quality control. Whether you are a pharmaceutical company, a nutraceutical manufacturer or a research organization, we can provide you with customized solutions to meet your needs and objectives.

Benefits of Tablet Coating

• Protection - The coating provides protection to the active drug ingredient from environmental factors like moisture, light, and air. This helps to maintain the stability and potency of the medication over its shelf life.
• Taste Masking - Some medications have an unpleasant taste or odor. The coating helps to mask the taste and make the tablet more palatable, making it easier for patients to swallow.
• Swallowing Ease - The coating makes the tablet smoother and less likely to stick to the throat, facilitating easier swallowing.
• Controlled Release - In some cases, the coating can be designed to control the release of the drug from the tablet. This allows for a sustained or delayed release of the medication, providing a controlled and consistent therapeutic effect over an extended period.

Types of Coated Tablets

Protheragen-ING is available in two main types of tablet coating.

Film Coating

Film coating is a modern and widely used tablet coating technology that involves applying a polymer film to the surface of the tablet. Film coating does not significantly affect the way the drug is absorbed into the body. Film-coated tablets are smaller in size and easier to swallow. It also breaks down easily due to agitation and moisture.

Film-coated formulations are mixtures of several ingredients including polymers, plasticizers, colorants, and solvents.

We can develop two types of film coatings:

• Organic solvent-based film coating: We use an organic solvent to dissolve the polymer and form a uniform film on the tablet. Although the use of organic solvents is not preferred, film coating with hydrophobic or lipophilic polymers requires the use of organic solvents when the water solubility of the coating material is low. In addition, coating processes using organic solvents reduce hydrolytic degradation of the drug. Organic solvent-based coating can be used for moisture-sensitive drugs.
• Aqueous film coating: We use aqueous solutions of polymers to coat tablets. Aqueous film coatings are considered to be more environmentally friendly as compared to organic solvent-based coatings.

Enteric Coatings

Enteric coatings are designed to protect tablets from the acidic environment of the stomach and to ensure their release in the intestines. These coatings are resistant to gastric juices but will dissolve in the alkaline environment of the intestine. This type of coating is commonly used for drugs that are sensitive to gastric acid or require targeted delivery to the intestine.

Fig. 1 (A) from left to right: caplet prior to coating, caplet after coating and cross section of coated caplet. (B,C) SEM images of internal structure of cross section of a coated caplet. (Seo K-S, et al. 2020)

Polymers for Pharmaceutical Coating

• Cellulose acetate phthalate (CAP).
• Cellulose Acetate Trimellitate (CAT).
• Methylcellulose (MC).
• Ethylcellulose (EC).
• Hydroxyethyl Cellulose (HEC).
• Hydroxypropyl Methylcellulose (HPMC).
• Polyvinyl Pyrrolidone (PVP).
• Shellac.
• Zein.
• Eudragit L-100-55.

The General Preparation Process for Coated Tablets

(1) Core Formulation: We mix API with other excipients to form a homogeneous mixture. The excipients may include binders, fillers, disintegrants, and lubricants.

(2) Tablet Pressing: We use a tablet press to press the core formulation into tablets. The tablets are typically round or oval in shape.

(3) Coating Preparation: We prepare coating materials by dissolving polymers or sugars in a suitable solvent or using an aqueous solution. The coating solution may contain additives such as plasticizers, pigments, and opacifiers.

(4) Coating Application: We place the tablet in a coating pan or drum and spray the coating solution onto it using a coating system. The process may involve multiple coats to achieve the desired thickness and properties.

(5) Drying and Curing: After coating, we dry the tablets with hot air to remove solvents or water. Some coatings may require curing or additional drying steps to ensure proper film formation.

(6) Quality Control: Our coated tablets undergo rigorous quality control testing to ensure integrity, uniformity, and performance. Tests may include weight variation, thickness, dissolution, and stability tests.

If you are in need of coated tablet services, please contact us by phone or email.