The selection of excipients in direct tablet pressing is very important. In addition to the performance of general tablet excipients, the most important requirement for excipients is that the excipients should have good fluidity and compressibility, as well as appropriate bulk density and large drug capacity (that is, adding more drugs without significant adverse effects on their fluidity and compressibility). The types of auxiliary materials commonly used for direct tablet pressing are:

1. Microcrystalline cellulose

Microcrystalline cellulose is a white or almost white powder, odorless and tasteless. It is insoluble in water, ethanol, acetone or toluene. It has very good compressibility, certain fluidity and disintegration. It is an excellent filler and effective dry adhesive for tablets. After being pressed into tablets, it has good hardness and does not affect disintegration. This variety has a large capacity for drugs, and its dosage can range from 5% ~ 65%. But this variety has hygroscopicity.

2.Pre gelatinized starch

Pre gelatinized starch this product is white powder, odorless, tasteless, with good fluidity. The angle of repose of domestic products is 36.6 degrees, with good compressibility; It has the function of lubrication, which can reduce the force of pushing the tablet out of the mold hole; It has good disintegration and dry adhesion, which can increase the hardness of the tablet and reduce the brittleness. This product is an ideal multi-functional auxiliary material for powder direct tablet pressing, and the dosage is generally 5% ~ 20%.

3.lactose

Lactose spray dried lactose is used as a supplementary material for powder direct compression, and it is white crystalline powder with no hygroscopicity. The surface of the pressed tablet is smooth and beautiful, and the drug is released quickly; It has good fluidity and adhesion. It is an ideal filler for tablets. When the dosage is more than 50%, the hydrophobicity of the drug can be improved.