Evaluation of Packaging Materials in Freeze-Drying: Use of Polymer Caps and Nested Vials and Their Impact on Process and Product Attributes

Current trends in the pharmaceutical industry led to a demand for more flexible manufacturing processes with smaller batch sizes. Prepackaged nested vials that can be processed as a unit were introduced into the market to fulfill this need. However, vial nests provide a different thermal environment for the vials compared to a hexagonal packaging array and could therefore influence product temperature profiles, primary drying times, and product quality attributes. Polymer caps with the possibility of vial closure inside the freeze-drying chamber were developed to remove the risks and need of a crimping process. A general concern with the use of such caps is the possibility of an increase in resistance to water vapor flow out of the vial. This case study investigated the effect of the LyoSeal(®) and PLASCAP(®) polymer caps and EZ-fill(®) nests on the freeze-drying process. Amorphous and partially crystalline model formulations were freeze-dried. Process data and product quality attributes were compared for regularly stoppered vials and vials with polymer caps as well as vials in a hexagonal packaging array and nested vials. The results indicated no increased resistance or impeded water vapor flow by the polymer caps. Differences in the macro- and microscopic appearances of products and a trend towards lower product temperatures were observed for the investigated nest type compared to a regular hexagonal packaging array. Consequently, the polymer caps could be used as an alternative to regular stoppers without affecting freeze-drying process data or product quality attributes, while the different thermal environment of nested vials should be considered.