Polysorbate 20 (PS20) is a commonly used surfactant in biopharmaceutical formulations. It is a heterogeneous surfactant containing a distribution of fatty acid esters, which are subject to hydrolytic degradation, generating free fatty acids (FFAs). The FFAs can form visible or subvisible particles in drug product on stability. A previous FFA solubility model, developed by our group, predicts solubility limits for the three most prevalent FFA degradation products of PS20: lauric, myristic, and palmitic acid. The model takes into account two formulation parameters, pH and PS20 concentration, and their effect on FFA solubility. This work identifies a third parameter that has an impact on FFA solubility: PS20 ester distribution. When PS20 is hydrolytically degraded, the ester distribution of the remaining surfactant changes on stability. Ester distribution is known to influence the critical micelle concentration (CMC) of PS20 such that the monoesters have a much higher CMC compared to the higher-order esters (HOE). We hypothesize that as PS20 degrades, the CMC changes, affecting the proportion of PS20 that is present in micelles and capable of sequestering and solubilizing FFAs in these micelles. Here, PS20 was separated into monoester, HOE, and polyol fractions. The monoester and HOE fractions were mixed together to generate the mock degradation profiles of hydrolytically degraded PS20. FFA solubility was measured as a function of the concentration of these mock-degraded (MD) PS20s. The results indicate that ester distribution does have an impact on FFA solubility, especially at higher MD PS20 concentrations. HOEs solubilize up to 30 μg/mL more lauric acid than an equivalent amount of monoesters at a MD PS20 level of 0.06% w/v. With the addition of % HOE peak area fraction as a third parameter representing the ester distribution of PS20, the refined FFA solubility model more accurately predicts FFA solubility in protein formulations at 5 °C. The refined model suggests that drug products containing trace levels of host cell proteins (HCPs) that preferentially degrade HOEs of PS20 are at a higher risk of particle formation.

中文翻译：

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改进对生物制药药物产品中游离脂肪酸颗粒形成的预测：在聚山梨酯 20 降解过程中结合酯分布。

聚山梨醇酯 20 (PS20) 是生物制药配方中常用的表面活性剂。它是一种多相表面活性剂，含有脂肪酸酯的分布，这些脂肪酸酯会发生水解降解，产生游离脂肪酸 (FFA)。FFA 可以在稳定的药物产品中形成可见或不可见的颗粒。我们小组开发的先前 FFA 溶解度模型预测了 PS20 三种最常见的 FFA 降解产物的溶解度极限：月桂酸、肉豆蔻酸和棕榈酸。该模型考虑了两个配方参数，pH 值和 PS20 浓度，以及它们对 FFA 溶解度的影响。这项工作确定了对 FFA 溶解度有影响的第三个参数：PS20 酯分布。当 PS20 水解降解时，剩余表面活性剂的酯分布会随着稳定性发生变化。已知酯分布会影响 PS20 的临界胶束浓度 (CMC)，因此与高阶酯 (HOE) 相比，单酯具有更高的 CMC。我们假设随着 PS20 降解，CMC 会发生变化，从而影响胶束中存在的 PS20 的比例，并且能够隔离和溶解这些胶束中的 FFA。在这里，PS20 被分离成单酯、HOE 和多元醇部分。将单酯和 HOE 部分混合在一起以生成水解降解的 PS20 的模拟降解曲线。FFA 溶解度作为这些模拟降解 (MD) PS20 浓度的函数进行测量。结果表明，酯分布确实对 FFA 溶解度有影响，尤其是在较高的 MD PS20 浓度下。在 0.06% w/v 的 MD PS20 水平下，HOE 比等量的单酯多溶解多达 30 μg/mL 的月桂酸。添加 % HOE 峰面积分数作为代表 PS20 酯分布的第三个参数后，改进的 FFA 溶解度模型更准确地预测了 5 °C 下蛋白质制剂中的 FFA 溶解度。改进后的模型表明，含有痕量宿主细胞蛋白 (HCP) 的药物产品会优先降解 PS20 的 HOE，因此形成颗粒的风险更高。