Lili Feng, Chemical & Analytical Development, Novartis Pharmaceuticals Corporation, One Health Plaza, East Hanover, NJ 07936, Zhaoxia Liu, Novartis Pharmaceutical Corporation, East Hanover, NJ 07936, and Peter Karpinski, Novartis Pharmaceuticals Corp., One Health Plaza 436/2253, East Hanover, NJ 07963-1080.
Raman spectroscopy has proven to be a powerful tool in the characterization of polymorphic materials. In this study, in situ Raman spectroscopy is used to investigate the effect of solvent on polymorphic transformations of an API in development. Multiple polymorphic forms of the API have been isolated and characterized. At room temperature, the conversion from form A to form B is spontaneous in most solvent systems. However, other forms can be generated in some solvent systems, and the correlation between solvent used and the form generated seems to be specific. It is suspected that transitional solvates are formed during equilibration or evaporation, with a subsequent rapid desolvation upon solid/liquid separation.