title: Characterization of anhydrous and hydrated pharmaceutical materials with THz time-domain spectroscopy.
abstract: The identification of anhydrous and hydrated forms of pharmaceutical substances is of great importance in pharmaceutical science and industry. We report the use of THz time-domain spectroscopy (THz-TDS) for pseudopolymorph investigation. The anhydrous forms of pharmaceutical substances including caffeine, theophylline, D-glucose, and ampicillin exhibit different THz absorption spectra from their hydrated forms, presumably due to their different intermolecular vibrational modes mediated by hydrogen-bonding. The data from X-ray powder diffractometry (XRPD) confirm the crystallinity differences between the anhydrous and hydrated forms. The temperature-dependent THz spectra of caffeine hydrate were also recorded, and it demonstrates that THz-TDS can be used to monitor the dehydration process of drug hydrates. We conclude that THz-TDS is an advantageous technique for the pseudopolymorph identification and study, and has great potential to become a process analytical technology (PAT) in pharmaceutical production and quality control.
authors.affiliation: Center for Terahertz Research, Rensselaer Polytechnic Institute, Troy, New York 12180, USA.
authors.forename: Hai-Bo
authors.initials: HB
authors.lastname: Liu
authors.forename: Yunqing
authors.initials: Y
authors.lastname: Chen
authors.forename: X-C
authors.initials: XC
authors.lastname: Zhang
mesh_terms: D000667:Ampicillin / Q000737:chemistry; D002110:Caffeine / Q000737:chemistry; D002626:Chemistry, Pharmaceutical; D005947:Glucose / Q000737:chemistry; D006860:Hydrogen Bonding; D013057:Spectrum Analysis / Q000379:methods*; D013806:Theophylline / Q000737:chemistry; D014867:Water; D014961:X-Ray Diffraction
chemical_list: D014867:Water; D002110:Caffeine; D000667:Ampicillin; D013806:Theophylline; D005947:Glucose