In recent years, biological drugs containing proteins have been increasingly used in pharmacy. In order to stabilize proteins in liquid parenteral pharmaceutical forms, several excipients must be added to the formulation, including polysorbates. Polysorbates are often used in pharmacy as well-tested surfactants that improve the physico-chemical properties of soaps, cosmetics, eye drops, and food. Despite all their good properties, they tend to break down in two ways: by hydrolysis and auto-oxidation. Such decomposition has a strong impact on the quality or stability of the medicine, as this alone is inadequate when the polysorbate is decomposed. In order to avoid this, a good evaluation and characterization of polysorbates is necessary, i.e., the content and composition of only these should be determined, which is mostly done using analytical techniques of liquid chromatography and nuclear magnetic resonance, as well as using mass spectrometry.
As part of the master's thesis, we investigated the effectiveness of the oxidation of polysorbate 20 and polysorbate 80 with different oxidants, at different temperatures and exposure times. Intentional oxidation allows us to better understand the various mechanisms of polysorbate degradation in biological drugs. To evaluate the content and purity of polysorbates, we used the method of high-resolution liquid chromatography coupled with a charged aerosol detector. We found that 2,2'-azobis-(2-methyl-propionamidine)-dihydrochloride is the most effective of the tested oxidants. Oxidation took place faster at elevated temperature and took place to a greater extent after a longer time. Saidoxidant was then used for the intentional degradation of polysorbates in the presence of various antioxidants and we determined which antioxidant inhibits oxidation best. We found that with the addition of the antioxidant ascorbate, the oxidation of polysorbate still takes place. Added mannitol only partially inhibited polysorbate oxidation, while added methionine completely inhibited oxidation. The oxidation of polysorbates was also confirmed by a complementary method - nuclear magnetic resonance spectroscopy.
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