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