PURPOSE: To evaluate a simple calorimetric method for estimating the fragility of amorphous pharmaceutical materials from the width of the glass transition region. METHODS: The glass transition temperature regions of eleven amorphous pharmaceutical materials were characterized at six different heating and cooling rates by differential scanning calorimetry (DSC). RESULTS: Activation energies for structural relaxation (which are directly related to glass fragility) were estimated from the scan rate dependence of the glass transition temperature, and correlations between the glass transition widths and the activation energies were examined. The expected correlations were observed, and the exact nature of the relationship varied according to the type of material under consideration. CONCLUSIONS: The proposed method of determining the fragility of amorphous materials from the results of simple DSC experiments has some utility, although "calibration" of the method for each type of materials is necessary. Further work is required to establish the nature of the relationships for a broad range of amorphous pharmaceutical materials.
PURPOSE: To evaluate a simple calorimetric method for estimating the fragility of amorphous pharmaceutical materials from the width of the glass transition region. METHODS: The glass transition temperature regions of eleven amorphous pharmaceutical materials were characterized at six different heating and cooling rates by differential scanning calorimetry (DSC). RESULTS: Activation energies for structural relaxation (which are directly related to glass fragility) were estimated from the scan rate dependence of the glass transition temperature, and correlations between the glass transition widths and the activation energies were examined. The expected correlations were observed, and the exact nature of the relationship varied according to the type of material under consideration. CONCLUSIONS: The proposed method of determining the fragility of amorphous materials from the results of simple DSC experiments has some utility, although "calibration" of the method for each type of materials is necessary. Further work is required to establish the nature of the relationships for a broad range of amorphous pharmaceutical materials.
Authors: Karel Six; John Murphy; Ilse Weuts; Duncan Q M Craig; Geert Verreck; Jef Peeters; Marcus Brewster; Guy Van den Mooter Journal: Pharm Res Date: 2003-01 Impact factor: 4.200