2000 Volume 60 Issue 2 Pages 160-165
Amorphous of cefditoren pivoxil was prepared by grinding or spraydrying. When the amorphous samples were stored at 40°C and 96% relative humidity (RH) or heated by using DSC, crystallization was not observed for the spray-dried sample, but it was for the ground sample. Glass transition accompanying enthalpy relaxation was evaluated for the spray-dried and the ground cefditoren pivoxil by means of a modulated-temperature differential scanning calorimetry (MTDSC). Glass transition temperature (Tg) and relaxation enthalpy (ΔH) of the ground sample were remarkably varied by storage at a temperature below Tg, but for the spray-dried sample no significant change in Tg or ΔH was observed by storage. We could interpret that the ground sample was less stable and that it was stabilized by storage below Tg, but the spray-dried sample was more stable. Since the energy level of the amorphous region between spray-dried and ground samples was different, the difference of the crystallization of the amorphous samples could be observed by storage at 40°C and 96% RH or heating by using DSC.
