The storage of high-quality biopharmaceuticals is a major challenge for the industry. Proteins are easily affected by changes in ambient conditions and react sensitively to changes in their environment. Changes in the structure will have fatal consequences; in certain cases, they do not only result in a loss of efficacy, but may even cause pathological effects.
This means the process of storing an active protein substance must be the result of an exceptionally careful and sophisticated design process and all influencing factors must be known since the substance will often need to be stored for years.
The pharmaceutical industry has found deep-freezing to be a stable method of storing protein solutions. The active ingredient is cooled in freezing chambers or in controlled freezing containers until the whole bulk solution has reached the required temperature level. However, we know from practice that rearrangements and structural effects will occur in proteins even in the frozen state, which can also result in changes to their native structure.
The frozen protein solution becomes increasingly concentrated as ice crystals form during freezing. The auxiliary substances, such as buffer salts, gradually lose their effect depending on their solubility. Myriad of influencing parameters exist and their effects differ widely for each substance. This is why they are examined for each product individually in the lab, using tailor-made F&T equipment. The aim is to understand the product behaviour in one freeze and thaw cycle in order to be able to derive optimum process understanding from this knowledge.
Once the basic behaviour of the protein solution during freezing has been understood, the F&T processes developed in the lab will be scaled to pilot scale. The freezing process is analysed, optimised further and precisely defined. The specified process is the basis for industrial processing and thus an important element in the development of optimum storage of the protein substance.
Only at temperatures below the glass transition temperature can it be assumed that there will be no more movements and structural changes in the structure of the proteins in solution. Consequently, a temperature of below -70°C was defined as a prerequisite for the freezing system for particularly sensitive products.
While freezing containers on an industrial scale of up to 500 l are already established practice for an industrial freezing process in the moderate temperature range, the large-scale solution for freezing highly sensitive and active pharmaceutical proteins in a low temperature range of <-70°C needed a new development. The first 200 l freezing container for freezing down to -85°C emerged in a cooperation project, which was yet another result from the many years of cooperation between ZETA and Boehringer Ingelheim in the field of freezing processes.
The development of the new vessel included some major challenges for the ZETA engineering team.Together with the freezing systems, which serve the different process volumes, ZETA covers the entire development process of a freezing unit – from the product investigations to the freezing plant on an industrial scale. Professional project teams take the current stage of every project product into account. In this way, the mutual knowledge gain can be maximised through cooperation, the product quality can be maintained in the best possible way and the time to implement processes and set up plants can be accelerated in an optimum manner.
At the end theoretical calculations on freezing rates were empirically confirmed in the test series. These results enabled the customer to develop a concrete calculation model, which is the central element of a scientific publication commissioned.
The ZETA R&D Specialist Team is happy to answer further questions in detail!
Get in contact with Birgit Pittermann, ZETA Head of R&D