Scale-up procedure for primary drying process in lyophilizer by using the vial heat transfer and the drying resistance

The objective of this study is to design primary drying conditions in a production lyophilizer based on a pilot lyophilizer. Although the shelf temperature and the chamber pressure need to be designed to maintain the sublimation interface temperature of the formulation below the collapse temperature, it is difficult to utilize a production lyophilizer to optimize cycle parameters for manufacturing. In this report, we assumed that the water vapor transfer resistance (Rp) in the pilot lyophilizer can be used in the commercial lyophilizer without any correction, under the condition where both lyophilizers were operated in the high efficiency particulate air (HEPA)-filtrated airflow condition. The shelf temperature and the drying time for the commercial manufacturing were designed based on the maximum Rp value calculated from the pilot lyophilizer (1008 vials) under HEPA-filtrated airflow condition and from the vial heat transfer coefficient of the production lyophilizer (6000 vials). And, the cycle parameters were verified using the production lyophilizer of 60000 vials. It was therefore concluded that the operation of lab- or pilot-scale lyophilizer under HEPA-filtrated airflow condition was one of important factors for the scale-up.