title: Differentiated thermal crystallization from amorphous chenodeoxycholic acid between the ground specimens derived from the polymorphs.
abstract: Crystallization behavior of amorphous chenodeoxycholic acid (CDCA) was studied using X-ray diffraction (XRD), infrared (IR) spectroscopy and differential scanning calorimetry (DSC). The two polymorphs of CDCA, form I (mp 166 degrees C) and form III (mp 119 degrees C), were ground with a vibrational mill. The ground samples of both crystal forms showed halo X-ray diffraction patterns. DSC curves of the amorphous samples derived from the form I and form III showed exothermic peaks due to the crystallization to the form I at 120 and 147 degrees C, respectively. When the ground form III was mixed with the ground form I, the crystallization temperature shifted to a lower temperature as the content of the ground form I increased. In the case of co-ground sample of form I and form III, the crystallization to form I crystals proceeded by two different modes. These results indicate that the physicochemical state was different among the ground samples of the form I and form III, and that the crystal nuclei played an important role on the crystallization process of the amorphous CDCA.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Chiba University, 1-33 Yayoicho, Inage-ku, Chiba 263-8522, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Oguchi
authors.forename: Nahomi
authors.initials: N
authors.lastname: Sasaki
authors.forename: Tetuya
authors.initials: T
authors.lastname: Hara
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Tozuka
authors.forename: Keiji
authors.initials: K
authors.lastname: Yamamoto
mesh_terms: D002152:Calorimetry, Differential Scanning; D002635:Chenodeoxycholic Acid / Q000737:chemistry*; D003460:Crystallization; D008968:Molecular Conformation; D017550:Spectroscopy, Fourier Transform Infrared; D014961:X-Ray Diffraction
chemical_list: D002635:Chenodeoxycholic Acid