Most coating operations require the use of a certain amount of solvent (organic solvent or water) to dissolve or disperse the coating material. In the hot-melt coating technique, the hot-melt coating material is coated on the surface of the substrate in a molten state, so that no solvent is used at all. Over the past decade, researchers have conducted many researches on hot-melt coating technology. The technology has been widely used in metals, pharmaceuticals, and food industries in foreign countries. The use of this technology can improve the taste of pharmaceutical preparations. Inhibition of the degradation of drugs in preparations and the control of release in pharmaceutical preparations, the domestic pharmaceutical industry has relatively little research in this area.
The hot-melt coating technology has many advantages over current conventional coating techniques, such as the absence of any solvents. Because there is no evaporation of the solvent, the operation time is greatly reduced, and the process of evaporation and disposal of the organic solvent is also omitted, and it is an environmentally friendly technology.
Although the current domestic application of water-based coating technology is more common, but it also has deficiencies, it is inevitably facing one of the biggest problems - the existence of microorganisms, in fact, this technology can not completely control the existence of microorganisms. In addition, some hydrolyzable drugs are not suitable for aqueous coating systems. The hot-melt coating shows superiority.
If the same purpose of controlled drug release is achieved, the amount of hot melt wax material is much less than the amount of polymer currently used. The price of hot-melt coating materials is relatively low, and using this technology can reduce production costs.
Domestic researchers used Compritol 888ATO as a coating material to investigate the specific parameters and influencing factors of the hot-melt coating technology using theophylline as a model drug, and further investigated the influence of the particles' own factors on the later coating, and compared the hot-melt coating and The effect of other methods of addition on the release of theophylline was discussed initially for the use of hot-melt coating technology in the pharmaceutical industry.
In the experiment, the researchers took 500 grams of theophylline particles in the GLATTGPCG-1.1 material room, using the top spray coating mode, the adjustment parameters are as follows: air volume 70 cubic meters / hour, inlet air temperature 75 °C ~ 78 °C, the actual material temperature 66 °C ~ 68 °C, atomization pressure 2.5bar, outlet temperature 55 °C, shotcrete flow 10 g / min, hot melt material temperature 120 °C, nozzle hot air temperature 140 °C.
For hot-melt coatings, bed temperature is an important process variable for using top-blown hot-melt coating technology. The temperature of the coating area determines the adhesion and spreadability between the molten material and the substrate. If the coating temperature is too high, the coating material will not adhere to the substrate; on the contrary, if the temperature is too low, the coating material cannot achieve a good spread on the surface of the substrate. Therefore, this also affects the surface coating properties of the formulation, thereby affecting the release properties of the drug.
Relatively speaking, the melting point of Compritol 888ATO is 69°C~74°C, so other parameters are fixed and the temperature of the material is controlled at 57°C~58°C, 61°C~62°C, and 66°C~67°C, respectively. It is 6%. The researchers measured the degree of release, found that when the coating temperature was 60 °C, the particles obtained only slightly decreased compared with the uncoated particles at the initial stage of release, and the coating temperature was 67 °C, it showed a sustained release effect. It can be seen that when the coating temperature is too low, the coating material does not completely deposit on the surface of the substrate and may even fall off without forming a dense coating film.
The size and uniformity of the dispersion of the melt coating material are also very important factors. The droplet size is affected by the compressed air pressure, the viscosity of the molten coating material, and the spray rate. Relative to the substrate, the smaller the droplets, the higher the coating efficiency. The greater the atomizing air pressure, the smaller the droplets; the viscosity of the molten material should meet the atomization conditions. The spray rate affects the quality of the coating and the degree of aggregation. Other important variables are the temperature of the molten coating material and atomizing air, the batch size of each batch and the size of the substrate.
The researchers found that different amounts of Compritol 888ATO have an effect on the release rate of the drug: the weight gain of the coating material has a significant effect on the early release of theophylline particles. The 3% coating weighted particles produced 30 minutes of theophylline release (40%) in 30 minutes of theophylline release (52.2%) and more than 6% of the coated weight gain particles.
The researchers took the same batch of theophylline particles hot-melt coating, after coating the particles of different particle sizes were measured after the release was measured and found that as the particle size decreases, the degree of release gradually reduced. This may be mainly due to the relatively large amount of coating material deposited on the surface of smaller particles. The researchers also screened theophylline particles for batch1 (200-400 μm) and batch2 (700-800 μm), respectively, and coated them according to the above parameters. The weight gain was the same as 6%. The cumulative release was measured and found with the substrate. As the particle size increases, the release of theophylline slows down.
The hot-melt coating technology has many advantages over current conventional coating techniques, such as the absence of any solvents. Because there is no evaporation of the solvent, the operation time is greatly reduced, and the process of evaporation and disposal of the organic solvent is also omitted, and it is an environmentally friendly technology.
Although the current domestic application of water-based coating technology is more common, but it also has deficiencies, it is inevitably facing one of the biggest problems - the existence of microorganisms, in fact, this technology can not completely control the existence of microorganisms. In addition, some hydrolyzable drugs are not suitable for aqueous coating systems. The hot-melt coating shows superiority.
If the same purpose of controlled drug release is achieved, the amount of hot melt wax material is much less than the amount of polymer currently used. The price of hot-melt coating materials is relatively low, and using this technology can reduce production costs.
Domestic researchers used Compritol 888ATO as a coating material to investigate the specific parameters and influencing factors of the hot-melt coating technology using theophylline as a model drug, and further investigated the influence of the particles' own factors on the later coating, and compared the hot-melt coating and The effect of other methods of addition on the release of theophylline was discussed initially for the use of hot-melt coating technology in the pharmaceutical industry.
In the experiment, the researchers took 500 grams of theophylline particles in the GLATTGPCG-1.1 material room, using the top spray coating mode, the adjustment parameters are as follows: air volume 70 cubic meters / hour, inlet air temperature 75 °C ~ 78 °C, the actual material temperature 66 °C ~ 68 °C, atomization pressure 2.5bar, outlet temperature 55 °C, shotcrete flow 10 g / min, hot melt material temperature 120 °C, nozzle hot air temperature 140 °C.
For hot-melt coatings, bed temperature is an important process variable for using top-blown hot-melt coating technology. The temperature of the coating area determines the adhesion and spreadability between the molten material and the substrate. If the coating temperature is too high, the coating material will not adhere to the substrate; on the contrary, if the temperature is too low, the coating material cannot achieve a good spread on the surface of the substrate. Therefore, this also affects the surface coating properties of the formulation, thereby affecting the release properties of the drug.
Relatively speaking, the melting point of Compritol 888ATO is 69°C~74°C, so other parameters are fixed and the temperature of the material is controlled at 57°C~58°C, 61°C~62°C, and 66°C~67°C, respectively. It is 6%. The researchers measured the degree of release, found that when the coating temperature was 60 °C, the particles obtained only slightly decreased compared with the uncoated particles at the initial stage of release, and the coating temperature was 67 °C, it showed a sustained release effect. It can be seen that when the coating temperature is too low, the coating material does not completely deposit on the surface of the substrate and may even fall off without forming a dense coating film.
The size and uniformity of the dispersion of the melt coating material are also very important factors. The droplet size is affected by the compressed air pressure, the viscosity of the molten coating material, and the spray rate. Relative to the substrate, the smaller the droplets, the higher the coating efficiency. The greater the atomizing air pressure, the smaller the droplets; the viscosity of the molten material should meet the atomization conditions. The spray rate affects the quality of the coating and the degree of aggregation. Other important variables are the temperature of the molten coating material and atomizing air, the batch size of each batch and the size of the substrate.
The researchers found that different amounts of Compritol 888ATO have an effect on the release rate of the drug: the weight gain of the coating material has a significant effect on the early release of theophylline particles. The 3% coating weighted particles produced 30 minutes of theophylline release (40%) in 30 minutes of theophylline release (52.2%) and more than 6% of the coated weight gain particles.
The researchers took the same batch of theophylline particles hot-melt coating, after coating the particles of different particle sizes were measured after the release was measured and found that as the particle size decreases, the degree of release gradually reduced. This may be mainly due to the relatively large amount of coating material deposited on the surface of smaller particles. The researchers also screened theophylline particles for batch1 (200-400 μm) and batch2 (700-800 μm), respectively, and coated them according to the above parameters. The weight gain was the same as 6%. The cumulative release was measured and found with the substrate. As the particle size increases, the release of theophylline slows down.
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