Stabilizing Polysorbate 20 and 80 Against Oxidative Degradation

Polysorbates are stabilizers typically required in therapeutic protein formulations. On account of their chemical structure, polysorbates are prone to degradation, which can render a pharmaceutical product instable or incompliant. The purpose of this study was to investigate if the addition of butylhydroxytoluene (BHT) and butylhydroxyanisole (BHA) protects polysorbate 20 (PS20) and polysorbate 80 (PS80) against oxidative degradation. PS20 and PS80 solutions containing BHA, BHT—or as control without an antioxidant—were stressed by exposure to air at 40°C for 7 weeks. The following assays were performed: ferrous oxidation-xylenol orange assay, liquid chromatography coupled to UV and mass spectrometry (MS), pH measurement, liquid chromatography fluorescence micelle assay, headspace–gas chromatography coupled with MS. PS20 and PS80 solutions containing an antioxidant were found to be more stable, as demonstrated by lower peroxide levels, lower free fatty acid contents, stable pH, intact polysorbate micelle structure/composition, and less volatile degradants. PS20 and PS80 solutions containing BHT or BHA are more stable against oxidative degradation compared to nonstabilized solutions. It might be beneficial to formulate bulk polysorbate with the antioxidant(s) to ensure stabilization during all process steps.