From Batch to Continuous: Freeze-Drying of Suspended Vials for Pharmaceuticals in Unit-Doses

In response to the current trend in the pharmaceutical industry, a new concept for the freeze-drying of pharmaceuticals in unit-doses is presented: the continuous freeze-drying/lyophilization of suspended vials. This configuration makes it possible to set up a continuous freeze-drying process that produces a final product with similar characteristics to those traditionally obtained by means of the batch process but which avoids the drawbacks of conventional, batch freeze-drying. The feasibility and advantages of this new concept are presented in this work. Continuous freeze-drying has been found to improve heat transfer uniformity and reduce the primary drying duration by 2–4 times. As far as the structure of lyophilized products is concerned, SEM micrographs of the lyophilized samples showed that this technology improves vial-to-vial and intravial homogeneity.