A new standard for lyophilizer characterization, comparability and efficient technology transfers

Abstract

This paper details the implementation of the ΔT and ΔP methodologies—recently introduced in the literature—for monitoring of mass flow during sublimation, demonstrating their application across multiple pharmaceutical companies. As a relatively new approach, this work is assessing its benefits, limitations, and potential enhancements. The mass flow of sublimated vapor per vial is the key parameter proposed to characterize the lyophilization process and for process transfer. Traditional methods like Tunable Diode Laser Absorption Spectroscopy (TDLAS) are expensive and difficult to implement in existing commercial equipment. The ΔT method measures the temperature difference between the inlet and outlet of the heat transfer fluid (usually silicone oil) circulating in the shelves. The sublimation process is endothermic, consuming heat and causing a slight temperature drop, which can be quantified to derive sublimation flow rates. The ΔP method utilizes the pressure difference between the chamber and the condenser, which occurs due to the vapor flow during sublimation. Both methods provide comparable data, validating their effectiveness in monitoring sublimation flow. The methods allow for monitoring of the primary drying segment of a freeze-drying process without the need for expensive equipment. They can be used to ensure that the freeze-drying cycle operates as intended, facilitating process transfers and scale-ups. The findings suggest that even older freeze-drying equipment can be retrofitted to utilize these methods, enhancing operational efficiency. The methodologies have been tested using process data by multiple pharmaceutical companies. The results indicate that the pressure drop and calorimetric methods are effective, cost-efficient alternatives to traditional monitoring techniques. They provide valuable insights into the freeze-drying process, helping optimize lyophilization cycle times. They also help establish equivalence between the primary drying endpoints at laboratory and industrial scales. These methodologies are suggested as a best practice for future technology transfers and process monitoring helping to ensure product quality, efficiency and consistency in biopharmaceutical manufacturing and contribute to the digital twin for lyophilization.