(502b) Removal of Impurity from API and Reduction of Agglomeration during Drying

In this work we describe removal of an impurity from an API which was not detected in HPLC and can be observed only in NMR in specific solvents. A kinetic model was developed for conversion of this impurity to API using online NMR. Based on the prediction from the model the impurity was converted into API and isolated after crystallization. There were challenges in milling of the API due to large chunks (about 1 -2 cm) which were formed due to agglomeration during filtration and drying. This issue was resolved by using filter dryer, application controlled vacuum and application of agitation in the filter dryer based on LOD of the API during drying.