High-Shear Wet Granulation Process in Drug Production
aInstitute of Chemical Technology, Prague, bZentiva-Leciva Co., Prague, cInstitute of Chemical Process Fundamentals, Academy of Sciences of the Czech Republic, Prague
The authors resume the most important knowledge on the mechanism, course and control of industrial wet granulation of pharmaceuticals in stirred granulators. Measurement of main impeller power input, conditions and consequences of heat transfer in granulation, sensitivity of the process to the shape and size of particles of active substance and transfer of data from a pilot-plant granulator to plant conditions are discussed more in detail. The most reliable method of monitoring the course of wet stirred granulation and for detection of the optimum state of granulated mixture is the measurement of main impeller power input. In addition to the input, also the batch temperature can be monitored which, however, depends more on the total time of stirring than on the actual state of the granulated mixture.The selection of an optimum amount of moisture and, subsequently, also the course of wet granulation are affected by the shape and size of particles of active substances. Their shape and size can differ with manufacturers and also depending on storage package. The successful data transfer from pilot-plant to plant conditions requires not only geometrical similarity but also the same process parameters.
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