All about the bilayer tablet manufacturing process


Double-layer tablets, sometimes referred to as double-layer tablets, are a newer technology for the development of controlled release formulations. They contain a combination of two or more active pharmaceutical ingredients in a single dosage form. Nowadays, the use of bilayer tablets is growing. Bilayer tablets are more suitable for the gradual release of a combination of two active ingredients. Dual-layer tablet technology separates two incompatible substances in which one layer is immediate release as a loading dose and the second layer is controlled / sustained release as a maintenance dose. Two incompatible drugs can also be formulated in a bilayer tablet by adding an inert middle layer. Bilayer tablets can also make it easier for patients because they can reduce the number of daily doses needed, thereby simplifying diets. This article will tell you how these tablets are made.

Manufacturing process

Bilayer tablets are prepared with one layer of drug for immediate release, with the second layer designed to release drug later, either as a second dose or in a sustained release form. Compressing separate layers of each drug so as to minimize the area of ​​contact between two layers is another method of preparing bilayer tablets containing two incompatible drugs. An additional intermediate layer of inert material can also be included to ensure the layers do not come into contact. To produce a suitable tablet formulation, specific requirements, such as sufficient strength and the desired drug release profile, must be met. Sometimes it can be a difficult task for the formulator to achieve these conditions, especially in the formulation of bilayer tablets where a double compression technique is involved, due to the poor flow and compatibility characteristics of the drug, which results in poor flowability and compatibility. will result in styling and / or lamination. The compaction of the material consists of both compressibility and consolidation.

There are different types of bilayer tablet presses: single sided tablet press, double sided tablet press and bilayer tablet press with motion control. A single sided press has a double feed with two chambers separated from each other. Each chamber is fed by gravity or manual force, which produces the individual layers of the tablet. Double-sided presses use the compressive force to monitor and control the weight of the tablets. Displacement controlled tablet presses measure displacement by measuring the applied precompression force instead of the weight of the tablet.

When manufacturing bilayer tablets using a single-sided press, with two different feed hoppers, this is first filled with the different formations required for the finished tablet. The granulation of the first layer, which will become the bottom layer, feeds a die as the cavity passes under a feed frame. The cavity then continues to the initial compression stage, where the matrix is ​​packed to form the first layer. The tablet is compacted at careful pressure, without too much force, as this would prevent a complete unit with the filling of the second layer.

The next step is where the matrix passes under a second feed frame and fills with the granulation of the second layer, which has already been determined to be suitable for the desired total weight of the tablet after its combination with the first layer. . The die then passes through final compression rollers which apply the appropriate force to achieve the desired hardness of the finished tablet.

The manufacturing process ends with the step of ejecting the press for the die tool. The upper and lower punches are lifted through the use of lifting and ejecting cams. The cams punch the tablet, ejecting the finished tablet from the die cavity. To learn more about making bilayer tablets, read here.


Making bilayer tablets is more expensive than making single layer tablets for several reasons. First, the tablet press costs more. Second, the press generally runs slower in bilayer mode. Third, the development of two compatible granulations is essential, which means more time devoted to the development, analysis and validation of the formulation. If there is not enough mechanical strength and not well controlled weight control of the individual layers, it will impact the bilayer compression and quality attributes of the bilayer tablets. Therefore, getting an understanding of the layers is essential to enable the design of a robust product and process.

The manufacture of bilayer tablets has its own unique challenges. Additional formulation and development activity is often required, and this can be associated with formulation development coupled with equipment and process optimization. Types of technical challenges include delamination of tablets, cross-contamination layers, separation of layers, maintaining acceptable weight and depth control, and achieving acceptable yields and flow rates.

Safety and quality compliance practices and standards should be used in the manufacture of any medical product. In addition, the ability to acquire and analyze data, modern quality control and development laboratories, powder containment solutions and on-site storage all need to be considered. It is also essential to ensure that tablet presses are cleaned consistently and undergo daily inspections. For more information on preventive maintenance, read here.


This article presented an understanding of bilayer tablets and how they are made. For more information on related products, see our other guides or visit the Thomas Supplier Discovery Platform to locate potential sources of supply or view details on specific products. For example, you can find more than 150 suppliers of medicinal, pharmaceutical and nutraceutical tablets.

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