Tuning of Operating Conditions in View to Access To a Single Polymorph by Spray Drying

Spray drying is a suitable method for the manufacturing of many pharmaceutical drugs. Ideally, this method leads in one step to a dry solid with the appropriated particle size distribution (PSD) [1], the right polymorph with the desired crystallinity [2]. Moreover, it is implemented in the continuous mode, so a high productivity is a priori accessible. Therefore, when using spray-drying, there is then no need for large vessels. In practice many parameters have an impact on the PSD, the crystallinity and the physical nature of the powder (amorphous, mixture of forms [3], pure form, etc). It is even possible, by tuning the operating conditions such as the nature of the solvent or the solution concentration [4], to crystallize a single polymorphic form. This communication examines some of these parameters and exemplifies their influences on the final product.