(372b) Spray Drying Proteins: Advances in Process Understanding Using the Model Protein Human Serum Albumin

Biopharmaceuticals, such as monoclonal antibodies and protein therapeutics, steadily increase in importance in the pharmaceutical industry. Advances in research, with the need for biopharmaceutical products to treat various diseases speed up the development of new protein-based drugs and the production of these valuable entities. Transferring proteins from liquid state to solid state has already been shown to be beneficial for the proteins’ stability and enables milder storage condition ¹. So far, freeze-drying is the gold standard when it comes to transferring protein solutions to protein powder on an industrial scale. However, freeze drying is a cost-and, energy-intensive process with common drying times from hours to days ^2,3. Spray drying, as an alternative, enables continuous protein drying with flexible process design, at atmospheric conditions and milder temperatures enable avoidance of temperature induced denaturation. However, commonly spray dried powders exhibit larger residual moisture as drying takes place in the order of seconds ^2,3.

Therefore, we investigated at first optimal process parameter sets for a spray drying process at mild temperatures. With the findings, different spray drying process parameter sets for the model protein human serum albumin (HSA) were selected for optimal spray drying at low residual moisture and high yields. Spray drying HSA with these sets was performed under low bioburden conditions with the drying gas being nitrogen. Further, the drying process was monitored in terms of inlet drying gas, and outlet drying gas conditions, as well as temperatures of the feed and product. Besides the process investigation, the impact of the process sets on the properties of the protein is tested with a standardized set of methods after spray drying in solid and resolubilized state. Further, we set up a model to gain further insight and enable the linkage of process knowledge and protein properties for future process development.

The talk will highlight the lessons learned from the primary process parameter investigation at mild conditions and from spray drying the model protein HSA. Process knowledge will be included gained from investigations on the influence on the protein properties. A comparison will be drawn with spray dried HSA and the developed model used to depict the spray drying process. We aim to support development for spray drying as alternative technology and industrialization to fully exploit its benefits for protein-based therapeutics.

Literature Cited

1. Maltesen MJ, van de Weert M. Drying methods for protein pharmaceuticals. Drug Discov. Today Technol. 2008;5(2-3):e81-8.
2. Ratti C. Freeze-Drying Process Design. In: Ahmed J, Rahman MS, editors. Handbook of Food Process Design. Hoboken: Wiley-Blackwell [Imprint]; John Wiley & Sons, Incorporated, 2012:621–647.
3. Langford A, Bhatnagar B, Walters R, Tchessalov S, Ohtake S. Drying of Biopharmaceuticals: Recent Developments, New Technologies and Future Direction. Jpn. J. Food Eng. 2018;19(1):15–24.