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Pharmaceutical Coating Technology (Part 6)

The development of film-coating processes Graham C.Cole SUMMARY To develop a film-coating process requires a laboratory test rig that can be scaled-up to meet production requirements. All the process parameters need to be optimized. A scheme is discussed here that provides an integrated computer-controlled system designed for aqueous film coating in a side-vented pan. A comparison is made of energy requirements of a column-coating system and a coating pan. All the major operational coating parameters can be measured and recorded under the overall control of a microcomputer. The monitored values are displayed on a computer screen at selected short. | Page 152 6 The development of film-coating processes Graham C.Cole SUMMARY To develop a film-coating process requires a laboratory test rig that can be scaled-up to meet production requirements. All the process parameters need to be optimized. A scheme is discussed here that provides an integrated computer-controlled system designed for aqueous film coating in a side-vented pan. A comparison is made of energy requirements of a column-coating system and a coating pan. All the major operational coating parameters can be measured and recorded under the overall control of a microcomputer. The monitored values are displayed on a computer screen at selected short intervals e.g. 5 s and at selected longer intervals e.g. 1 min they can be printed as hard copy. This chapter describes the selection of instruments to measure the appropriate parameters how the coating process may be optimized using a laboratory side-vented pan the loop closed to provide automatic control and the process scaled-up to control successfully the coating of production size batches. 6.1 INTRODUCTION To set up a suitable experimental rig required for the general development of all coating processes instruments are required to measure and record data from the process parameters. First it is necessary to determine which parameters have a critical effect on the performance of the coating system to produce a tablet that is pharmaceutically acceptable. The following process parameters are possibilities Page 153 Inlet air flow rate. Inlet air temperature. Inlet air humidity. Outlet air flow rate. Outlet air temperature. Outlet air humidity. Leakage air rate to the atmosphere through the casing. Spray concentration. Spray temperature. Spray flow rate. Quantity of attrition from cores by filtration of the exhaust air . Quantity of spray not applied to tablets by filtration of the exhaust air . Tablet-bed temperature. Power torque to keep the drum turning. Rotational speed of the drum. Electrical power .