Comparison of crystallinity of cefditoren pivoxil determined by X-ray, differential scanning calorimetry and microcalorimetry

The heat of crystallization and heat of solution of cefditoren pivoxil of d ifferent crystallinities were determined by differential scanning calorimet ry and isothermal microcalorimetry, respectively. The heat of crystallizati on and heat of solution of ground cefditoren pivoxil showed good linear cor relation with the degree of crystallinity determined by Ruland's method by powder X-ray diffractogram, The changes in crystallinity of amorphous cefdi toren pivoxil by adsorption of alcohol vapor could be evaluated for small a mounts of sample by use of heat of crystallization. Since the apparent diss olution rate of cefditoren pivoxil of various crystallinities correlated wi th the heat of solution, microcalorimetry was found to be useful for predic tion of dissolution behavior.