Tablet Capping: Causes and Prevention

Tablet capping is a tablet defect that occurs during the compression process when the upper or lower part of the tablet separates horizontally from the main body, resembling a cap. It can lead to tablets with compromised integrity, reduced drug content, and poor visual appearance. Understanding the causes of tablet capping and implementing preventive measures are essential to ensure high-quality tablet manufacturing. Here’s a look at the causes and prevention of tablet capping:

Causes of Tablet Capping

• Poor Formulation: Inadequate or improper formulation, such as insufficient binder or disintegrants, can lead to weak tablet structure and capping during compression.
• Inadequate Compression Force: Insufficient compression force during tablet compression can result in poor tablet cohesion and cause capping.
• Excessive Air Entrapment: If air becomes trapped within the tablet during compression, it can weaken the tablet structure and contribute to capping.
• Poor Granulation: Inconsistent granulation can lead to variations in particle size and distribution, affecting tablet integrity and increasing the likelihood of capping.
• Over-Lubrication: Excessive use of lubricants can reduce interparticle friction and lead to poor tablet bonding, contributing to capping.
• Inadequate Flow of Granules: Poor flow properties of granules can result in uneven filling of die cavities, causing differences in tablet density and contributing to capping.
• Machine-Related Factors: Mechanical issues with the tablet press, such as worn or misaligned punches, can affect tablet compression and cause capping.

Prevention of Tablet Capping

• Optimize Formulation: Ensure a well-balanced and appropriate formulation with sufficient binders and disintegrants to promote tablet integrity.
• Control Compression Force: Adjust the compression force to the optimal level to achieve proper tablet bonding and prevent capping.
• Minimize Air Entrapment: Reduce air entrapment by using efficient deaeration techniques during granulation or compression.
• Optimize Granulation: Maintain consistent and proper granulation to ensure uniform particle size and improve tablet uniformity.
• Control Lubrication: Use lubricants judiciously to avoid over-lubrication and maintain sufficient interparticle friction.
• Ensure Proper Flow: Enhance granule flow properties through appropriate granulation techniques and use of flow enhancers if necessary.
• Maintain Equipment: Regularly inspect and maintain the tablet press to prevent mechanical issues that could lead to capping.
• In-Process Checks: Implement in-process checks during tablet compression to detect and address capping issues promptly.
• Quality Control: Conduct thorough quality control testing to ensure tablet quality, integrity, and absence of capping.

Conclusion

Tablet capping is a common tablet defect that can compromise the quality and appearance of tablets. By understanding the causes and implementing preventive measures, tablet manufacturers can ensure that tablets have the desired integrity, content uniformity, and appearance, meeting quality standards and providing safe and effective medications to patients.