Obtaining heat transfer coefficients (K) distribution directly from mass flow measurements during the sublimation step of freeze-drying.

The knowledge of heat transfer coefficients (K) and their distribution is a crucial element in the successful transfer of a freeze-drying process to a new piece of equipment. Nevertheless, the implementation of the classical ice sublimation method is resource consuming, particularly in the industrial context, which represents a significant barrier to its application. This paper demonstrates that the K distribution can be calculated from the measurement of mass flow during a freeze-drying operation by reversing the results of process simulation calculations.

A Simple and Cost-Effective Technique to Monitor the Sublimation Flow During Primary Drying of Freeze-Drying Using Shelf Inlet/Outlet Temperature Difference or Chamber to Condenser Pressure Drop.

As lyophilization continues to be a critical step in the manufacturing of sensitive biopharmaceuticals, challenges often arise during the scale up to commercial scale or the transfer from one manufacturing site to another. While data from the small-scale development of the lyophilization cycle is abundant it is typically much more difficult to extract important information from commercial scale cycles, due to the lack of process analytical technologies available on the commercial line. There is often a reluctance to include wireless temperature or pressure probes during GMP operations due to the additional contamination risk, and retrofitting equipment such as the TDLAS can be prohibitively expensive.