Thermal characterization of citric acid solid dispersions with benzoic acid and phenobarbital.

The glass transition temperatures of citric temperatures of citric acid glass were determined by differential scanning calorimetry to be 10.2 and 13.5 degrees for in situ and bulk-prepared samples, respectively. Mechanical stress on citric acid glass induced foci for crystallization. Benzoic acid addition to citric acid glass decreased its glass transition temperature while phenobarbital addition increased its glass transition temperature, the latter forming a glass solution.