What are the different types of granulation technologies IV
Writer： admin Time：2020-03-31 22:11 Browse：℃
To connect with the last subject What will influence the wet granulation
1.Screen types for wet granulation
1)Nylon screen: It does not influence medicine stability and elasticity. It can be used for wet and non-viscous mixture. If it viscous, screening is low. But as mixture is repeatedly rubbed and mixed, granules made by it will be hard and nylon screen can be broken easily.
2)Galvanized wire screen: It can be used for viscous mixture. But metal shavings (broken wires) might be mixed in granules and even influences some medicines’ stability. Magnet can be installed at key places to absorb wires.
3)Stainless steel screen: Pure SS screen of good quality obtains good granulating performance. However, broken SS wires will mix into granules and cannot be absorbed by magnet.
4)Plate screen: No metal shavings can be mixed into granules. But it is expensive and slow.
Q: If oscillating granulating machine is used for wet granulation, will tensity of screen install influence granule quality.
A: If screen is installed loosely, mixture viscosity can be increased during mixing to harden wet granules. Otherwise, granules will be fine and loose. Therefore, tensity of screen should be proper.
2.Drying and drying equipment
Drying is a process during which wet materials can be dehumidified.
1)Drying process for wet granules: It refers to the process where water expands to the surface of wet materials and then is gasified and evaporated. When the surface water is evaporated, water inside granules repeats the above process.
2)Points for attention in drying wet granules
A.Wet granules should be dried as soon as possible. Otherwise, wet granules will be out of shape, agglomerated or go bad.
B.Medicines dissolving in thin ethanol and being easily hydrolyzed should be dried as soon as possible, since ethanol is volatile and water will increase them, which speed up medicine hydrolysis.
C.Drying speed should be controlled strictly. Drying speed depends on external conditions and expansion of liquid inside material. External conditions include humidity, temperature, flowing and material distribution.
D.Drying temperature should increase gradually, otherwise a hard film will form on the surface of granules after drying and influence water evaporation.
E.If granules contains sugar and starch, , sudden increase of temperature will melt sugar and gelatinize starch, which will influences tablet disintegration.
3)Drying equipment
A.Drying oven: Several supports are installed inside drying device, on which material plates are put. Air, after preheating, enters drying chamber and dry materials horizontally.
B.Spraying drying device: Its structure and operation is same with that of spraying granulator. With large evaporating area and short drying time, this machine is applicable for heat-sensitive materials. Some products of it are crunchy hollow granules of good solubility.
C.Fluid bed drying device: Hot air pass through loose granule or powdery materials from the bottom to the top to form fluid status and dry.
Features: simple structure, convenient operation, fierce relative movement between granules and hot air, large contacting area, quick drying and application for heat-sensitive materials.
Vertical fluid bed drying machine is applicable to dry table granules which contains more fine powders.
Horizontal fluid bed drying machine is applicable to dry granules.
I.Application in pharmacy
1.Application in granule production
Granules refer to dry granule preparation which are made from medicines and appropriate auxiliary materials.
Pharmacopoeia of China (2005) regulates granule size clearly: The granules and powders can pass through #5 screen but not #1 screen and their weight doesn’t reach 15% of the total weight. (Generally, internal control standards regulate it in 10%.)
All granules should be granulated and passing rate must be high. In the process, all factors should be taken into consideration comprehensively and tests should be taken to make granulating formula.
Common granules: Azithromycin granules, Amoxicillin granules, etc.
2.Application in tablet production
Commonly, tablet can be produced by direct tablet pressing and granulation pressing. The latter one is used most widely. It is applicable for medicine that is stable to humidity and high temperature.
