Preparation of Enteric-Coated Capsules

Enteric-coated capsules are designed to resist disintegration and dissolution in the acidic environment of the stomach. Instead, they disintegrate and release their contents in the more alkaline environment of the small intestine. The enteric coating helps protect sensitive drugs from degradation in the stomach and allows for targeted drug release. Here’s an overview of the process involved in preparing enteric-coated capsules:

1. Formulation Development

The first step in preparing enteric-coated capsules is formulating the drug or API with suitable excipients. The formulation should be designed to provide the desired drug release characteristics and protect the API from stomach acid.

The formulation is typically in a granulated or powdered form.

2. Selection of Enteric Coating Material

The enteric coating material is carefully selected based on the specific requirements of the drug and the desired release profile. Commonly used enteric coating materials include cellulose acetate phthalate (CAP), hydroxypropyl methylcellulose acetate succinate (HPMCAS), and methacrylic acid copolymers (Eudragit). The coating material should be resistant to stomach acid but should dissolve or disintegrate in the alkaline environment of the small intestine.

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3. Coating Process

The coating process is typically performed using specialized equipment such as a fluid-bed coater or a pan coater. The capsules are placed in the coating equipment, and the enteric coating material is applied to the capsules in a controlled and uniform manner. The coating material may be dissolved in a suitable solvent to form a coating solution before application. The coating process may involve multiple layers of coating to achieve the desired level of enteric protection.

4. Curing

After the enteric coating is applied to the capsules, they may undergo a curing process. Curing involves subjecting the coated capsules to specific conditions, such as controlled temperature and humidity, to allow the coating to become fully formed and hardened. Curing helps enhance the stability and durability of the enteric coating.

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5. Quality Control and Testing

Throughout the preparation process, strict quality control measures are followed to ensure the enteric-coated capsules meet the required specifications. In-process checks are conducted to assess the coating thickness, uniformity, and integrity. Dissolution testing is performed to verify the enteric coating’s ability to withstand the acidic conditions of the stomach and release the drug in the desired manner in the intestinal environment.

6. Packaging and Labeling

After the enteric-coated capsules have undergone quality control checks and testing, they are packaged and labeled for distribution. Proper packaging protects the capsules from environmental factors and ensures their stability during storage and transportation.

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Conclusion

Enteric-coated capsules are prepared by formulating the drug with suitable excipients, selecting the appropriate enteric coating material, applying the coating to the capsules through a specialized coating process, and conducting quality control and testing. The enteric coating protects the drug from stomach acid and ensures targeted release in the intestine, making enteric-coated capsules an effective option for certain drug formulations that require specific release profiles or protection from gastric degradation.