Powder direct compression process

Direct compression of the powder means that the powder of the drug (or a raw material of the health care product) (or a certain proportion of the auxiliary material particles) is directly compressed into tablets. The direct compression of the powder is carried out by sieving and mixing the raw material powders without granulating (wet or dry particles), thereby simplifying the process, improving production efficiency and saving energy. It is suitable for raw materials that are wet, hot and discolored. Some raw materials are wet, hot, prone to discoloration, oxidation, and decreased content. The direct compression of the powder also helps the product to disintegrate or dissolve, and the quality of the finished product is stable. If conventional wet granulation is used, in the production process, the material is in contact with the solvent in the binder and dried at a high temperature to cause decomposition of the material and affect product quality. The powder direct compression process does not require wetting, bonding, drying, and granulation processes. The prepared tablet has a smooth surface, a short disintegration time limit, a small decrease in content, and an improved stability. At the same time, due to the small number of processes and short time, the chance of cross-contamination is reduced, the water is not exposed, and it is not susceptible to microbial contamination, which meets the requirements of GM P.

Comparison of direct powder tableting and granulation tableting process

The process of tableting and direct compression after granulation is as follows:

Wet granulation process:

Raw and auxiliary materials are crushed and sieved – mixed – granulated – dried – whole grain

Total Mix – Test – Tablet – Packaging

Dry granulation process:

Raw and auxiliary materials crushing and sieving – mixing – dry pressing – whole grain – total mixing

Laboratory – Tableting – Packaging

Powder direct compression process:

Raw materials are pulverized (or not pulverized), sifted – mixed – pressed – packaged

It is obvious from the above process that the process of directly compressing the powder is the most simplified, but the key to the process is whether the mixed material has the fluidity and compressibility required for tableting. Since the flowability and compressibility of the particles are better than the fluidity and compressibility of the powder, the purpose of the granulation is to solve this problem. What needs to be solved for direct compression is how to improve the shape of the powder, add excellent excipients, improve the fluidity and compressibility of the mixture, and improve the tableting equipment without granulating.

Improved tableting equipment

The flowability of the fine powder is always lower than that of the particles. It is easy to appear in the feeder or the flow is fast and slow, resulting in a large difference in the weight of the tablet. Adding a turbulent feeding or forcing the feeding device on the tableting machine can make the powder flow evenly. Mold hole. It is also possible to increase the preloading device, since the air present in the powder is more than the particles, and the top cover and the splitting phenomenon are easily generated when the tablet is pressed. The first solution is to reduce the tableting speed. The second is the second compression, that is, the first compression is the first, and the second is the final compression. Due to the increased compression time, it is advantageous to discharge the air in the powder, reduce the phenomenon of cracking, and increase the hardness of the tablet. The tablet press should have a good sealing and dust removal device. Because the powder is flying, when the powder is directly compressed, more dust will be generated and powder leakage may occur. Therefore, the tablet press should have an automatic sealing device. Good dust removal device and tight joint between the duster and the turntable.

Disadvantages of direct compression of powder

Due to the difference in density between the drug and the auxiliary material, the material is liable to generate static electricity during dry mixing, which makes the material directly compressed into layers easy to be delaminated, resulting in problems of weight difference and content uniformity. Excipients for direct compression are specially processed, such as spray drying, fluidized bed drying, spin drying or co-crystallization, so the cost of these excipients is higher. Most of the direct compression tablets can only hold 30% to 40% of the drug. For tablets with large drug specifications, a large amount of excipients need to be added, which makes the film too large to be swallowed, and is not suitable for direct compression.