The phase behavior of excipients in multicomponent pharmaceutical systems during freeze-drying involves a complex interaction between formulation components and processing conditions. Successful drug product and process development depends on thoroughly characterizing the phase transitions of excipients in both the frozen and drying stages, understanding their tendency to crystallize during processing, and identifying the physicochemical stability needs and critical quality attributes of the final product.
Raj Suryanarayanan, Ph.D., of the University of Minnesota, explains how excipient phase behavior influences the stability of the API, the intricate relationship between formulation composition and processing conditions, and the strengths and limitations of analytical techniques used to monitor phase transitions in frozen and freeze-dried systems.