100% Control of Controlled Ice Nucleation Vials by Camera-Supported Optical Inspection in Freeze-Drying

Freeze-drying is the drying technology of choice for sensitive biological drugs. On the one side, it is admired for its suitability for the stabilization of sensitive molecules. On the other side, it is a time-consuming production step posing challenges in process development and technology transfer. The application of controlled ice nucleation is one elegant approach to shorten freeze-drying times significantly and at the same time increase batch homogeneity. However, a reliable 100% control of the controlled nucleation step in each vial is essential, considering the impact of the nucleation temperature on product quality attributes. In this study, we introduce a camera-supported optical inspection method that utilizes the different superficial cake structures seen in controlled and random nucleated lyophilizates. Derived from the grayscale analysis, the new distinguishing criterion "average edge brightness" is introduced. Four different formulations containing Sucrose, Trehalose, and/or bovine serum albumin were freeze dried with random or controlled nucleation and analyzed with the new technology. A proof of concept is provided by the analysis of a similar-to-market lyophilized monoclonal antibody formulation freeze-dried with three different freezing protocols covering different nucleation profiles. For all investigated formulations and process conditions, the clear discrimination of controlled and randomly nucleated vials was possible. By this, the technology allowed for reliable, noninvasive, and automatable 100% monitoring of controlled nucleation success after freeze-drying.