Strategies to Prevent Edge Chipping in Coated Tablets

What is Edge Chipping and Why Does It Occur?

Edge chipping in coated tablets refers to the flaking or breaking of the tablet’s edges, often caused by mechanical stress, improper coating parameters, or inadequate formulation. This issue compromises the aesthetic and functional quality of the tablet, leading to increased rejection rates and reduced patient compliance.

This guide provides actionable steps to prevent edge chipping in coated tablets, ensuring consistent quality and durability.

Step 1: Strengthen the Tablet Core

A robust tablet core minimizes the risk of edge chipping. Strategies include:

• Binder Selection: Use binders like microcrystalline cellulose (MCC) or hydroxypropyl cellulose to enhance tablet cohesion and hardness.
• Compression Force: Optimize compression force during tablet pressing to achieve sufficient mechanical strength without over-compaction.
• Granulation: Employ wet or dry granulation to produce uniform and dense granules, improving core integrity.

Strengthening the core creates a durable foundation for the coating process.

Step 2: Optimize Coating Formulation

A properly designed coating formulation reduces mechanical stress on tablet edges. Recommendations include:

• Polymer Selection: Use flexible polymers like hydroxypropyl methylcellulose (HPMC) or ethyl cellulose for improved film elasticity.
• Plasticizers: Add plasticizers like triethyl citrate or polyethylene glycol (PEG) to enhance coating flexibility and reduce brittleness.
• Layering: Apply a sub-coating layer to protect edges before applying the main coating.

A balanced formulation ensures a resilient coating that withstands handling and transportation stresses.

Step 3: Optimize Coating Process Parameters

Adjusting process parameters ensures even coating application and minimizes mechanical damage. Key adjustments include:

• Spray Rate: Maintain a controlled spray rate to avoid over-wetting, which can weaken the coating layer.
• Pan Speed: Adjust pan speed to ensure gentle yet effective tablet movement, reducing edge impact.
• Atomization Pressure: Use appropriate atomization pressure to achieve uniform droplet size and coverage.

Optimizing these parameters reduces stress on tablet edges during coating.

Step 4: Improve Tablet Design

Tablet shape and dimensions play a crucial role in preventing edge chipping. Consider the following:

• Beveled Edges: Design tablets with rounded or beveled edges to minimize stress concentrations.
• Uniform Dimensions: Ensure consistent tablet size and shape to improve coating application and reduce mechanical stress.
• Surface Smoothness: Use smooth tablet surfaces to enhance coating adhesion and reduce vulnerability to chipping.

Thoughtful tablet design minimizes edge damage during handling and transportation.

Step 5: Control Drying Conditions

Proper drying ensures a stable and durable coating. Recommendations include:

• Temperature: Maintain drying temperatures between 40–60°C to prevent coating brittleness.
• Airflow: Ensure uniform airflow in the coating pan to facilitate even drying and reduce cracking.
• Intermediate Drying: Allow adequate drying between coating layers to strengthen each layer before applying the next.

Controlled drying reduces coating stress and enhances edge durability.

Step 6: Monitor and Adjust Tablet Handling

Improper handling during manufacturing or transportation can exacerbate edge chipping. Preventive measures include:

• Pan Loading: Avoid overloading the coating pan to minimize tablet collisions and edge impact.
• Gentle Transfer: Use vibration-free conveyors or padded surfaces to reduce mechanical stress during tablet transfer.
• Packaging: Use protective packaging materials to cushion tablets during storage and shipping.

Careful handling preserves tablet integrity and prevents edge damage.

Step 7: Conduct Rigorous Quality Control

In-process and post-coating quality checks ensure consistent results. Key tests include:

• Hardness Testing: Measure tablet hardness to ensure cores can withstand mechanical stresses.
• Coating Thickness Measurement: Use tools like micrometers or optical sensors to confirm uniform coating application.
• Visual Inspection: Regularly inspect tablets for edge defects during and after coating.

Quality control helps identify and address edge chipping issues early in the process.

Step 8: Validate and Scale-Up the Process

Validation ensures consistent results during large-scale production. Steps include:

• Pilot Trials: Conduct small-scale trials to refine parameters and minimize edge chipping risks.
• Process Validation: Validate coating parameters and handling protocols across multiple production batches.
• Documentation: Maintain detailed records of adjustments and quality results to support regulatory compliance.

Validation ensures scalable and reproducible solutions for edge chipping prevention.

Conclusion

Preventing edge chipping in coated tablets requires a combination of robust tablet core design, optimized coating processes, and careful handling. By strengthening the core, refining coating formulations, and implementing rigorous quality control, manufacturers can ensure consistent tablet quality and minimize rejection rates. Validation and attention to handling protocols further enhance durability and regulatory compliance.