Bi-layer Tablet Manufacturing

Creating a bi-layer tablet involves compressing two formulations into a single solid oral tablet. The process maintains a physical separation of the formulations by layering one on top of the other. It allows for the controlled delivery of a single or multiple active pharmaceutical ingredients in a single tablet. Bi-layer manufacturing is especially beneficial if one of the layers provides an immediate release and the other layer has a sustained release delivery.

Bi-Layer Manufacturing

Bi-layer tablets can be visually appealing because the manufacturing process makes a clear demarcation between the layers, assuming the finished tablet is not coated. But there are also practical reasons to choose bi-layer manufacturing, such as:

  • It can sometimes improve the intended therapeutic effect by separating two actives.
  • There is a work-around for compatibility issues, which includes a way to combine ingredients that cannot easily be blended into the final formulation.
  • It can offer a means of product line extension.
  • It can prevent abuse of a constituent ingredient by using an “antagonist” layer that foils the potential abuser’s attempts at extracting certain ingredients.

The steps in the double-layer manufacturing process include:

  • A tablet press that has two different feed hoppers is charged with the different formations that are necessary for the finished product.
  • The first-layer granulation, which is the bottom layer, feeds into the die as the cavity passes under the first feed frame.
  • The cavity continues through the initial compression stage, where the bi-layer tablet is “tamped” to form the first layer. However, it’s not hard enough to inhibit good cohesion with the second layer fill.
  • Next, the dies pass under the second feed frame and fill with the second layer granulation, which is appropriate for the desired total weight of the tablet when combined with the first layer.
  • The tools pass through final compression rolls that apply the appropriate amount of force to achieve the intended hardness of the tablet.
  • The process finishes as the tools proceed through the ejection stage of the press. The upper and lower punches are raised through the usage of raising and ejection cams, which eject the finished tablets from the die cavities.

Considerations for Bi-Layer Manufacturing

There are certain challenges for double-layer manufacturing, which include:

  • Cross-contamination, or color “bleeding”
  • Delamination, when the tablet falls apart when the two halves don’t completely bond
  • The production process results in lower output than single-layer tablets
  • Efficient first-layer sampling
  • Protection against “second-layer-only” tablets
  • Transitional rejects
  • Load cell resolution, because good resolution is essential for bi-layer tablets when the first layer is very thin, and it requires virtually no force for tamping
  • Weight control for individual layers
  • Yield optimization through recirculation
  • Ease of conversion from mono to double layer

Fette Compacting for All Your Bi-Layer Manufacturing Needs

Solutions Fette offers for “punching up” your bi-layer manufacturing include:

  • Dynamic sampling, which is our more commonly selected option, and static sampling mode
  • Point-specific vacuum options
  • Resolution of compression force monitoring
  • Fast-acting lower main-compression roll assembly (for immediate first-layer sampling)
  • Weight control options
  • A system that allows for weight control of both layers
  • Optional recirculation for one layer
  • Rapid, simple conversion from monolayer to double-layer

Fette Compacting is the only supplier that has been producing tableting presses and tools for more than 70 years. We create custom tableting tools based on your needs. Our specially developed punches include:

  • FS12, which offers up to 40% greater output
  • FS19, which has a 30% longer dwell time
  • EU19 FS, which has a 50% longer service life

We offer up to five specialty coating options, and our patented segment technology increases the output of the tablet press by 40% while significantly reducing changeover time, which helps eliminate conventional dies. We also offer safe transport, storage, and cleaning.

To learn more about our services or to get a quote, contact us today.

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