Abstract
About half of candidates for active pharmaceutical ingredients are poorly water soluble compounds. Amorphization of poorly water soluble drugs has attracted much attention due to improved dissolution characteristics and bioavailability of amorphous drugs. On the other hand, crystallization during storage is of concern for amorphous drugs. Therefore, evaluation of crystallization of amorphous drug is important for developing stable pharmaceuticals using amorphous drugs. In this article, feasibility of thermal method such as differential scanning calorimeter and isothermal microcalorimeter for evaluating crystallization of amorphous drugs and research topics on the crystallization of amorphous drug are described.