ABSTRACT
The preparation of polymorphic forms of rivaroxaban was carried out using a recrystallization method based on that for crystal form-Ⅰ. Preparation methods were developed for two crystal forms-Ⅱ (medicinal crystal form) and five crystal forms-Ⅳ and the crystals were then characterized. The crystalline form was identified by applying modern analytical means including X-ray powder diffraction (PXRD), differential scanning calorimetry (DSC), element analysis (EA), mass spectrometry (MS), and infrared spectrum (IR), and the morphology of different crystal forms was observed by scanning electron microscopy (SEM). The results show that the PXRD and DSC characteristics of prepared crystal forms-II and IV are consistent with those described in patents at home and abroad, and the test results with EA, MS and IR are in accordance with the chemical structure of rivaroxaban. The crystal form-I is lamellar, the crystal form-II is linear and crystalline form-IV is striped as determined by SEM. In summary, the methods for preparing crystal form-II and form-IV are reliable, the required reagents are easily available, the experimental conditions are easy to implement and the preparation process is simple. Our study provides a new reference for the production and application of rivaroxaban.
ABSTRACT
In this paper, three methods, differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and X-ray powder diffraction (PXRD), were used to characterize the structure of Palbociclib. The form-B crystal mixed in with form-A crystal, the effective form of Palbociclib, was quantitated by the single peak method (peak area method and peak height method) using X-ray powder diffraction. While the qualitative identification by DSC was not clear, SEM and PXRD quickly and effectively identified two types of crystal. The standard curve equations established by the peak area method and the peak height method are: y = 0.842 75x - 0.001 21 and y = 0.909 64x - 0.002 32. This suggests that the linear relationship of peak area method is better than that of peak height method (R2 = 0.986 17 and R2 = 0.985 83). The sensitivity of the peak area method (LOD = 1.17%, LOQ = 3.92%) are higher than the peak height method (LOD = 1.19%, LOQ = 3.97%). The methods from this study can be used to identify and quantify palbociclib form-A and form-B crystal rapidly.