Delivering technology solutions for spray coating systems and applications...

 

 

API Assay Deviation Case Study

Problem

Find the root cause of 10% decrease in drug assay in the last batch manufactured.  In this process, the drug is layered onto the tablets.  The only notable deviation observed from the process data was 2°C increase in exhaust temperature.

Problem Categories

Thermodynamics, troubleshooting, precision coating, coating pan, Wurster, thermocoat, PCTSWurster, and PCTSUni .
Solution

Identify potential causes that impact both the temperature and assay
bullet

Air flow rate and temperature impact temperature but not assay

bullet

Equipment setup impact assay but not temperature

bullet

Solids content and spray rate impact temperature and assay

Conduct thermodynamics analysis to determine if deviations in solids content and spray rate explain the changes to the temperature and assay.
Analysis of Process Prior to Atypical
Analysis of Solids Content Change
Using the same heat loss, determine the solids content at 2°C higher exhaust temperature.

Solids content of 37.2 %, which is 25% than the 30% solids content, should result in 25% higher drug assay.  Solids content change does explain the observations.
Analysis of Spray Rate Change
Conclusions
10% decrease in assay and 2°C rise in exhaust temperature is explained by the 10% decrease in the spray rate.  The most likely root cause is the malfunction of the flow meter used to control the spray rate.