Many drugs are known to crystallize in different polymorphic forms or as solvates. Solubility, melting point, density, hardness, optical properties, vapor pressure, and a host of other physical properties may all vary with polymorphic form. Not only do the various crystal structures of a given pharmaceutical compound affect the efficacy of the drug, but they may also carry enormous legal implications. Much product revenue can depend upon the identification and patent protection of certain polymorphic forms. Thus, the control of crystallization is a very important process parameter, and techniques such as X-ray crystallography, infrared spectroscopy, Raman spectroscopy, and polarized light microscopy are routinely used in the characterization of crystalline drugs.

This presentation will involve the investigation of a variety of pharmaceutical polycrystalline films using infrared (IR) spectroscopic imaging. Preliminary data was collected using a conventional FT-IR microscope with visible polarized light capabilities. Correlating data was then collected using a commercially available IR imaging microscope.