The objective of this work was to develop a process for the microencapsulation of dexamethasone in a polymer matrix with a drug load of at least 50%, a burst release for the first three hours lower than 10% of the total drug, and a predicted extended release of at least 4 months. The target for particle size of the micro particles was a Dv90 between 15 and 20μm. Due to the high API load, an amorphous solid dispersion was not achieved. 

The alternative here described involves an initial spray drying (SD) step under conditions which force phase separation of the components, leading to the formation of nano-crystals of API. Afterwards, a second SD step is carried out to more efficiently encapsulate the generated nano-crystals.