Temperature Based Process Characterization of Pharmaceutical Freeze-Thaw Operations

Abstract

In biopharmaceutical production processes, freeze-thaw operations are used to ensure product integrity during long hold times, but they also introduce additional stresses such as freeze concentration gradients that might lead to a loss of protein activity. Process characterization of freeze-thaw operations at different scales should be conducted with attention to freezing time and boundary effects to ensure the product stability throughout the process and process development. Currently, process characterization often relies on one or very few temperature probes that detect freezing times based on raw temperature, which is largely influenced by freezing-point depression in case of concentrated solutions. A method to detect freezing based on the second derivative of temperature measurements from Fiber-Bragg-Grating sensors is presented to overcome this issue. The applicability of the method is demonstrated by process characterization of a novel small-scale freeze-thaw device with minimized boundary effects using freezing times of purified water and concentrated formulations. Freezing times varied from 35 to 81 min for temperatures between −60 and −20°C and impacted freeze concentration profiles. Furthermore, freezing time estimations based on the Plank equation revealed model limitations due to start-up temperature gradients, that can be corrected by an empirically extended Plank model. As a hypothesis, we conclude that freezing temperature, from a freeze concentration view, is less important in containers with small characteristic freezing distances such as freeze bags. Using a 2D-resolved temperature profile, a shift of the last point to freeze position from top to bottom of a container was observed when freezing above −30°C.

Raman spectroscopy as a process analytical technology to investigate biopharmaceutical freeze concentration processes

“…For higher freezing temperatures, the freeze concentration at the time of freezing increases with temperature. The correlation of freezing time t to the negative inverse of cooling temperature T cooling ( t ∼ −1/ T cooling ) as well as similar freeze concentration behavior in frozen bulk media was shown previously (Weber & Hubbuch, 2021).…”

“…The Raman probe and capillary for sampling are depicted in gray and green, respectively. Images were adapted from Weber and Hubbuch (2021). PTFE, polytetrafluoroethylene…”

“…In addition, the inlay insulates the bottom of a freezing chamber which reduces boundary effects further. An in‐depth device and process characterization has been described previously (Weber & Hubbuch, 2021).…”

“…However, the complex solidification of multicomponent solutions frozen in pharmaceutical applications currently lacks the process understanding necessary to overcome scalability issues. In the past, studies have been performed on novel freeze–thaw devices (Geraldes et al, 2020; Roessl et al, 2014; Shamlou et al, 2007; Weber & Hubbuch, 2021) with the aim of improved scalability and processes were mostly characterized by solute concentration in the frozen bulk (Kolhe & Badkar, 2011; Miller et al, 2013; Reinsch et al, 2015; Rodrigues et al, 2012). However, in large‐scale freezing processes, freeze concentration profiles are a result of the interplay of diffusive and convective mass fluxes.…”

Injection of an improperly stored proprotein convertase subtilisin/kexin type 9 monoclonal antibody in a patient with secondary dyslipidemia from nephrotic syndrome: a case report

“…Frozen drug-induced rash and allergic reactions should be considered. The frozen drug was exposed to a variety of stressors throughout the freezing process, including cold denaturation, freeze concentration, ice crystal formation, and potential excipient crystallization [14]. This rash might have occurred due to the specific protein precipitate in the frozen drug.…”