The three-dimensional arrangement of drug molecules in the solid state is of critical importance to physical properties such as solubility and bioavailability. Drugs often exhibit multiple stable polymorphs (crystalline packing motifs) that are interconvertible through mechanisms such as temperature changes, choice of crystallization solvent, and even ambient humidity. These various pharmaceutical polymorphs each exhibit unique identifying crystal lattice vibrations that occur in the THz region of the electromagnetic spectrum. Terahertz spectroscopy provides a rapid non-destructive method for the real-time monitoring of pharmaceutical polymorph content in bulk APIs (active pharmaceutical ingredients) for manufacturing line quality assurance and also in final formulated products to ensure long-term stability.
- A. J. Zaczek, T. M. Korter, Polymorphism in cis-trans Muconic Acid Crystals and the Role of C-H···O Hydrogen Bonds. Crystal Growth & Design, 17: (8) 4458-4466 (2017).
- S. P. Delaney, D. Pan, S. X. Yin, T. M. Smith, T. M. Korter, Evaluating the Roles of Conformational Strain and Cohesive Binding in Crystalline Polymorphs of Aripiprazole. Crystal Growth & Design, 13: (7) 2943-2952 (2013).