Polysorbates, especially polysorbates 80 (PS-80), are widely used in biotherapeutic formulation due to their capabilities to prevent the aggregation of proteins. Unfortunately, many studies have showed that the degradation of PS-80 can happen very easily via hydrolysis and oxidation. Transition metals iron (Fe) and copper (Cu) are the two potential root cause for the degradation process. The redox reaction of Fe(II) and Fe(III) generates the radicals, which trigger the degradation process. To prevent the degradation, chelating reagent such as EDTA can be added to chelate free iron in solutions. Similarly, citrate and histidine are also known for forming complexes with iron. To investigate the impact of iron on PS-80 degradation in citrate and histidine buffers, and to understand the mechanism of the iron-catalyzed oxidation of PS-80, we spiked Fe(II) and Fe(III) into four different matrices (water, histidine, acetate and citrate), respectively. The resulting solutions were analyzed for Fe(II) and Fe(III) by High performance liquid chromatograph coupled with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). To correlate the iron species ratio changes to PS-80 degradation, the samples were also analyzed by LC-MS. With the LC-MS results, we gained a better understanding of the iron-catalyzed oxidation of PS-80. Among the four matrix, no PS-80 degradation was observed in citrate buffer with Fe(III). By converting all iron species to Fe(III) in citrate buffer before adding PS-80, we can control the degradation of PS-80.
Learning Objectives:
Upon completion, participant will be able to gain a better understanding of the mechanism of metal induced PS-80 degradation.
Upon completion, participant will be able to understand the challenges of controlling PS-80 degradation and learn a novel approach to control PS-80 degradation.
Upon completion, participant will be able to learn analytical techniques to determine different metal species in pharmaceutical samples.