2. Conditions for glass formation –Physical stability conditions

The instability of amorphous solids and their ability to recrystallize are a major obstacle to their practical use. Crystallization of an amorphous pharmaceutical substance may occur during the amorphization process, during storage, or during administration, when the solid is placed in a liquid biological medium. However, this ability to recrystallize varies greatly from one compound to another. Potential candidates for formulation in amorphous form are those with a low tendency to crystallize during the amorphization process, and then during storage of the amorphized compound. This applies to active ingredients, excipients and/or their combinations. Recrystallization is a complex phenomenon, the mechanism of which is a long-standing concern in materials science. Its interest is more recent in pharmaceutical science, focusing on the specific case of molecular compounds. The description and...