| Abstract: | In this work the amorphous, I and II forms of clopidogrel hydrogen sulfate (CHS) were prepared and characterized by use of powder X‐ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The labile precipitate and oiling out during reactive crystallization were also firstly reported. Based on the solubility and thermochemical data, the amorphous form and I form is found to be monotropically related, while the I form and II form are enantiotropically related. In addition, both transformations from anhydrous form to I form and from I form to II form are greatly temperature‐dependent, which gives us a window to prepare each pure form. These results will contribute a better understanding about the polymorphic nature and crystallization mechanism of clopidogrel hydrogen sulfate. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) |
