Bilayer Medicine Tablet

As tablets are the most common format for taking medicine orally, it can be surprising that tablet production processes still present many quality control challenges for manufacturers. Tablets have the potential for a variety of defects, from external surface flaws to internal imperfections in the product’s layers that result from formulation issues. Visible and non-visible tablet defects can raise severe doubts in a consumer’s mind about the product’s quality and integrity, whether the problem exists in a single tablet or entire batches.

Some of the familiar tablet compression challenges that manufacturers typically experience include:

  • Insufficient tablet hardness
  • Inconsistent tablet weight
  • Tool damage
  • Incorrect formulation flow
  • Insufficient tablet pre-compression

Remedies to these tablet compression challenges include correcting tableting flow issues, modifying formulations, adjusting press parameters or tooling, and more. Read on to gain further insight into capping, a common tableting problem, and corresponding solutions.

What Is Pre-Compression, and How Is It Related to Capping Defects in Tablets?

Pre-compression is the preliminary compression force that tablet presses apply prior to the main compression. Operators often unknowingly set compression levels improperly, utilizing a percentage of the final compressive force, and this isn’t a recommended practice. Precision in pre-compression is crucial.

If an operator applies excess pre-compression, chances increase that tablets will fracture. On the other hand, if operators do not apply sufficient pre-compression, there will be increased air entrapment in the formulation. In the presence of fractures, the top of a pre-compression tablet, or its cap, may break away from its main body. This occurrence is tablet capping, and it most often happens as a result of trapped air in the powder material during pre-compression.

Other Causes of Capping in Tablets

Capping can be either formulation- or process-driven. In the formulation, there can be issues with interparticle bonding, too little moisture, or too many fines in the segregation. Alternatively, poorly configured punches or dies, excessive turret speed, and other factors can cause capping during production.

How to Prevent Capping in Tablets

To reduce capping, tablet manufacturers can try:

  • Ensuring Proper Permeability: Using a powder rheometer, operators can conduct a test to determine a formulation’s permeability and identify the likelihood that capping will occur. High formulation permeability means less air entrapment will take place during tableting, translating to reduced capping defects in tablets.
  • Choosing Effective Excipients: The proper excipients can withstand the tablet production process to create a strong formulation with minimal capping. To make the appropriate selections, utilize a compaction emulator or simulator to examine punch displacement and applied force within a formulation.
  • Modifying Press Parameters: In this case, rather than altering the tablet formulation, instead prevent capping by configuring the tablet press settings for pre-compression and main compression force, turret speed, and punch penetration.
  • Determining a Tablet’s Max Compactibility: At a certain point, the main compression force ceases to add to tablet strength. Any excess compression will instead minimize bonds between particles and result in capping. Decreasing the compression force can help solve the problem.
  • Reducing Speed: A decrease in turret speed may diminish capping potential in strain-rate-sensitive formulations.
  • Reconfiguring Press Tooling: By altering tooling features, operators can decrease tablet capping. This may mean reconfiguring punch heads to minimize head flat or utilizing tapered dies to remove air from a die cavity.

Maintenance and Training With Fette Compacting America

Adequate maintenance, calibrations, and training are vital for successful tableting machine operations and reducing capping. At Fette Compacting America, Inc., we offer these services to help customers save on time and resources. Our preventative maintenance services keep tablet presses at optimum functionality to limit process-related causes of capping. We will calibrate tablet press components to ensure pressed tablets remain within permitted tolerances. In addition, our experienced technicians are here to support clients’ staff. Fette Compacting provides training for press operators, teaching those responsible for maintaining and running tablet presses to ultimately avoid human errors and tablet defects.

Contact us today to learn more!

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