Optimization of a PEGylation process

Abstract: The PEGylation process is a covalent attachment between a protein (the pharmaceutical) and poly ethylene glycol (PEG) and since the beginning in 1977 PEGylation processes have been used to improve pharmaceuticals. PEGylation of a pharmaceutical achieves improved properties like greater solubility in water, longer residence time in vivo and extended shelf life. The PEGylation process is in general conducted with a batch reactor connected to a size exclusion chromatography (SEC) column or more common an ion exchange chromatography (IEC) column. The batch reactor achieves a yield of monoPEGylated protein at approximately 60 % and a 10 % yield of multiPEGylated proteins. Other processes are still under development like the size exclusion reaction chromatography (SERC). The report contains two parts, an experimental part and a simulation part. The experimental section tests the batch reactor in order to calibrate the kinetic constants. Experiments with a SERC column were also conducted. The simulation section created models for the batch reactor, the SEC column and the SERC column. The batch reactor model includes four reactions, three PEGylation reactions and one deactivation reaction. Both the SEC column and the SERC column are described with the General rate model. The SERC column is combined with a recirculation cycle and optimized for different objectives. The experimental results show fast kinetic reactions for the PEGylation that is suitable for the SERC column. The SERC column experiments resulted in a selective monoPEGylated protein production. The simulations resulted in a monoPEGylated protein yield at 82.3 % when recirculating the unPEGylated protein nine times. In future research a more detailed recirculation cycle can be simulated and validated with experiments. Also an automated injection loop where the reactants are mixed when entering the SERC column is able to improve the results.