in Wiley InterScience (www.interscience.wiley.com).A mathematical model that simulates temperature profiles during freezing process of standard pharmaceutical formulations (mannitol and BSA based) was set up in twodimensional axsymmetric space, and the ice crystal mean sizes were semi empirically estimated from the resulting temperature profiles. Water vapor mass transfer permeability values during sublimation step were also estimated from ice phase morphological parameters. All these numerical data were compared with experimental data, and a quite good agreement was observed that confirmed the adequacy of the present model calculations. It was confirmed that, for a given formulation, the mass transfer parameters during freeze-drying were strongly dependent on morphological textural parameters, and consequently, on the nucleation temperatures that fix the ice phase morphology. The influence of freezing rate was also predicted from the simulations, proving that an increase of cooling rates led to slower primary drying rates. 2007
During the primary drying stage of pharmaceutical solutions in vial, the sublimation front is the boundary between the dried and frozen layers that moves from the top of the vial to its bottom. While only few on-line measures are available, it is an important variable to control. This paper deals with the on-line partial differential equation model-based predictive control of the sublimation front position, assuming two strategies based on various availability of measurement used in the feedback loop. Through the MPC@CB control software, the robustness of the controller with respect to the main model parameter uncertainty is shown.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.