The application of film coatings is carried out in apparatuses for combined processes of granulation, drying and coating. A distinctive feature is the lower location of the nozzle. Two options for organizing the process are possible: applying a film coating directly to crystals or granules containing a drug substance; the preliminary stage is the layering of the drug substance on inert particles (pellets are most often used), after which a film coating is applied. During the coating process, a layer of particles is placed in a fluidized bed apparatus.
Coating in a fluidized bed of fine particles under supercritical conditions is a new emerging technology designed to encapsulate thermolabile products. Supercritical fluids are unique solvents, since their density is similar to the density of liquids, while the viscosity and diffusion coefficient are close to those for gases. Spraying supercritical solutions makes it possible to obtain droplets and particles of submicron size, as well as spraying onto other particles. Since the cohesive and adhesive forces for supercritical solutions are small compared with these indicators for organic solvents, the capillary compression force is also insignificant.
The production of Uniplast fixative adhesive tape rolls is carried out on an automatic coating line of the English company Coating and Laminating Systems LTD with a productivity of up to 28 m per minute. The line is intended for applying an adhesive layer to the base material (fabric, non-woven fabric, film). It consists of a number of sequentially installed nodes: unwinding node No. 1; coating unit; convection-type drying chamber with four zones; cooling and lamination unit; winding unit; unwinding unit No. 2. The automatic coating line has a software control system based on an industrial computer PROVIT-2200. In the appropriate menu of the computer set the necessary technical characteristics of the process. Parameters characterizing the heating process and temperature in the zones of the drying chamber are displayed on the monitor screen. Application of the adhesive coating on the base material on an automatic line is carried out by two methods - direct and transfer. With the direct method, the application of acrylate ...
As with sugar coatings, problems can occur after or during the film coating process. Coated tablets, pellets and granules may not be strong enough or delaminate during the coating process. Due to the fact that the film coatings are relatively thin, their ability to hide defects is much lower than that of the sugar coating. When using a film coating, various problems can arise. One example is adhesion, which occurs when the liquid feed rate exceeds the drying rate, which causes the bonding of tablets, pellets and granules and their further destruction.
With this type of coating, the drug substance from the tablets can be released instantly. These types of coatings include polymers developed by BASF: polyvinyl alcohol (PVA), Kollicoat IR white and Kollicoat Protect. PVA-based films are very flexible, but the coating process is possible only in a narrow range of technological parameters. This polymer is rapidly dispersed in water during the preparation of the dispersion for the film coating, forms shiny, non-sticky and very flexible films that do not crack during storage. To create a coating does not require the addition of a plasticizer. Kollicoat IR can be replaced with HPMC and other coatings with instant drug release in new tablet formulations. The use of Kollicoat IR increases the efficiency of the tablet coating process compared to HPMC. The polymer coating process with the best surface quality is possible in a wide ...
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