Pre-gelatinized starch contains two polymers: amylose and amylopectin. Amylose has a linear molecular structure and strong intermolecular binding forces. It is insoluble in cold water, swells in water, and has strong disintegration properties. Amylopectin has a branched molecular structure and is easily soluble in cold water. It is used as a binder in wet granulation.

Currently, it is generally believed that the structure of pre-gelatinized starch granules consists of radially arranged microcrystals. These crystals are mostly composed of amylopectin, while the amylose is interspersed in a disordered state throughout the granules, and the two starches are tightly bound together. A special spherical crystal structure. As long as there is sufficient energy, usually hot water at 90℃～100℃, the binding force between starch crystals can be overcome, and ordinary starch can be cooked into starch paste.

Pre-gelatinized starch (also known as fully pre-gelatinized starch) has better compressibility and flowability than ordinary starch, and is therefore also known as compressible starch. It no longer contains amylose, but is entirely amylopectin, which can be completely dissolved in cold water. Hot water is not needed to rinse the starch paste during granulation. However, it also loses the disintegration capacity of ordinary starch.

Part of the pre-gelatinized starch retains some of the amylose. After the gelatinization process is made into a slurry, the two components are partially mixed and opened to release the amylopectin inside the starch granules, thereby achieving adhesion without being glued. The amylose inside the starch granules has a strong disintegrating effect, so some pre-gelatinized starch has both fluidity and compressibility, and has both adhesive and disintegrating functions. Therefore, by controlling the starch gelatinization process and gelatinization rate, starch-based pharmaceutical excipients with different adhesion and disintegration properties can be obtained. Due to the strict control of the pre-gelatinization rate, its adhesion and disintegration properties are relatively stable, and the cost is lower than PVP and HPMC.