Freeze- and Spray Drying Support
Freeze-dried products are normally either completely amorphous or consisting of a homogenous mixture of amorphous and crystalline components. When deliberate amorphous phases are included in a product, it is commonly a more demanding task to ensure robust quality and stability compared to the case of crystalline products. By that, it is especially critical to build thorough understanding on the interplay between the freeze- or spray-drying manufacturing process parameters together with the chosen formulation components and the quality of the produced formulation. As example, the background to properties like glass transition temperature (Tg) and Tg-prime and their relation to the formulation composition and the freeze-drying process parameters must be well understood. An adequate characterization package during e.g. freeze-drying development should at minimum include characterization of the glassy state properties, evaluation of the powder cake texture and appearance, evaluation of the content of residual solvents and not the least determination of the level of amorphicity including polymorph identification of possible crystalline components. The same charcaterisation package is normally used also in support to stability studies in order to evaluate the initial quality followed by long term stability of the developed products. In some cases it is useful to complement the basic analysis package with e.g. analysis of the specific surface area of the powder cake since it often give useful information on the vial-to-vial and/or batch-to-batch consistency of the cake structure.
Spray-drying often demand similar characterization packages as for freeze-dried formulations but with more focus on Particle Characterization rather than evaluating cake structures.