A study was made of the possibilities of gradually decreasing the concentration of the toxic organic solvent in the process
of microsphere preparation. Ammonio methacrylate copolymer-based microspheres were prepared by spray drying or conventional
solvent evaporation techniques, and compared. The formulations were designed by varying the preparation methods and the concentrations
of four polar cosolvents as independent variables.
DSC was used to study the relationship between the changes in the independent variables and three of the main thermal events
of the microspheres. Raman spectroscopy was used to investigate and confirm the possible interactions between drug and copolymer.
Appropriate choice of the independent variables led to the molecularly dispersed drug in the polymer matrix. It was demonstrated
that only the nature of the preparation method caused significant variations in the structure and thermal behaviour of the