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Scale Up Case Study

Spray Rate Determination

Problem

Determine the processing condition in the large scale that reproduces the 12% RSD in tablet coating weight uniformity.

Problem Categories

Coating uniformity, coating pan, precision coating, scale up, and PCTSUni

Solution

The solution to this problem is solved by trial and error or using the optimization capability built into PCTSUni.  The slip and bypass factors for the large scale equipment must be known for this calculation.
Trial and Error Method
Enter the process conditions in PCTSUni to determine coating uniformity as shown below.  The pan speed to 7 RPM is used as the first guess.
The coating uniformity for this initial guess was 14.6%.  Changing the pan speed to 8.5 resulted in 13.5% RSD.  Decreasing the spray rate from 1000 to 800 g/min decreased the RSD to 12.6%, and decreasing the bed load from 100% to 90% fill level dropped the RSD to the target 12%.  The thermodynamic bridging must be done using this spray rate in order to achieve the same coating uniformity.
Optimization Method
PCTSUni has the following optimization screen to examine the effects of changes to multiple variables on coating uniformity.  Here, the effects of changing solids content, final bed density, and initial tablet weight on coating uniformity can be seen.