Background

Pharmaceuticals that rapidly dissolve in aqueous solutions (use-time dissolution type preparation) are manufactured by freeze drying. Freeze drying includes three steps: 1) “freezing” to freeze water and concentrating solutions, 2) “primary drying” to sublimate ice, and 3) “secondary drying” to evaporate water from solid parts. A high primary drying temperature can reduce drying time but, if this temperature is too high, structural collapse will occur. Thus, the maximum allowed temperature and proper annealing conditions that do not cause structural collapse have been examined. However, the conditions for freeze drying are not easily determined because the crystallization and transition behavior change depending on the type and concentration of additives. In this example, we performed in-situ observation of the crystalline phase transition during the actual freeze drying process using the low and middle sample temperature attachment.