Factors affecting film formation of coating machine

We all know that pharmaceutical companies cannot do without coating machines. Coating machines are equipment that wrap polymers around the tablet core to form a thin film. In order to improve the dissolution of water-insoluble drugs and improve their bioavailability, the insoluble drug hydrocortisone acetate is homogenized into very small nanocrystals using high-pressure homogenization technology, and the drug-loaded pellets are prepared by the suspension drug-coating method, and then the pH-dependent enteric coating film is coated on the pill core. The results show that 20 cycles of homogenization are required to obtain a nanoscale drug-containing suspension with a narrow particle size distribution and no change in the drug crystal form. The pellets made from nanocrystals that have been homogenized by high pressure have a faster dissolution rate than ordinary micron-sized drug pellets, and the drug release is more complete, and the enteric coating used can adjust the drug release.

Film formation mechanism and influencing factors:

1. The structure of the film on the tablet core after coating is not uniform, and the appearance is also different. This inhomogeneity is caused by the intentionally added insoluble ingredients (such as colorants), and the film is not formed continuously during the coating process. In most coating processes, the polymer solution is adhered to the solid tablet core by spraying, then dried, and then sprayed again. This process needs to be repeated many times until the coating is completed. In order to obtain a good coating effect, the formation mechanism of the film must be understood first.
2. The minimum speed should be selected so that the tablet core does not stop for a moment on the tablet bed. This requires experimental optimization. A method can be used to determine the speed range. When a certain amount of tablet cores are loaded into the drum, try to start from the minimum speed and slowly increase it. At the same time, observe that the tablet cores anywhere in the drum can flip, that is, the blind area of ​​the tablet core flipping can be eliminated. At this time, the increased speed is the minimum speed. After that, continue to increase the drum speed. When a single tablet core jumps out of the tablet bed area covered by the atomization, it can be considered the maximum applicable speed. The purpose of studying the optimization of this speed range is to guide the operator to reasonably set the speed and make necessary preparations for the speed change of the second coating process.
3. Film-coated sustained-release pellets have become a new dosage form that has developed rapidly internationally. They are one of the hot spots in the research and production of sustained-release and controlled-release preparations, such as gastric floating pellets, pulsed-release pellets, self-emulsifying pellets, colon-targeted pellets, etc., which can enable ordinary pellet preparations to obtain specific excellent properties and achieve ideal drug release patterns and release curves. There are many sustained-release pellet preparations on the market, such as Contac sustained-release capsules produced by Sino-US SmithKline, diltiazem hydrochloride sustained-release pellets produced by Aifa Pharmaceutical Group, and venlafaxine hydrochloride sustained-release capsules produced by Wyeth, USA.
4. The basic composition of the film coating solution prescription includes film-forming agent (coating material), solvent, plasticizer, colorant, pore-forming agent, insoluble filler, etc. The composition of the film coating prescription plays a key role in the coating quality.
The development of society has driven the development of coating machines. With the rapid development of high-efficiency coating machines and film coating liquid technology in recent years, it has become the mainstream of domestic tablet production. At present, there are many directions for evaluating the quality of film coating, often including surface roughness, surface gloss, film thickness uniformity, and film coating defects. With the advancement of science and technology, coating machines are constantly improving their technology to better serve pharmaceutical companies.