Objective

Polysorbates 20 and 80 are the most used surfactants for the development of parenteral protein formulations, because of their beneficial safety and stabilisation profile. Although, showing excellent stabilisation properties, the stabilisation mechanism(s) of these surfactants for aqueous protein formulations are still unclear. Different stabilisation models have been discussed in the literature, among them the possible formation of protein-surfactant micelle complexes.

Methods

This study focusses on the determination of the self-association properties of compendial grade polysorbate 20 HP (PS 20 HP) and polysorbate 80 HP (PS 80 HP) with regard to the formed micelle size (by dynamic light scattering, DLS), the concentration upon which the surfactant molecules self-associate (cmr, critical micelle concentration range) to form micelles, and the related surface tension. Surface tension and micelle size were determined as a function of temperature, as well as composition of the formulation (presence of a buffer salt and influence of ionic strength).

Results

The critical micelle concentration range values (cmr) at 25 °C are between 15–75 μM for PS 20 HP, but considerably lower for PS 80 HP with 7–16 μM, depending only slightly on the formulation composition. With increasing temperature, the cmr decreases slightly. PS 80 HP forms larger micelles (R_h = 4.5 nm) compared with PS 20 HP (R_h = 3.5 nm) (25 °C). The temperature dependency of the micelle size is more pronounced for PS 80 HP.

Conclusions

Based on these results, the suggested stabilisation mechanism, especially for antibody formulations, by the formation of antibody-polysorbate micelle complexes, is critically discussed, and the current study shows that this stabilisation mechanism is not likely, for commonly used monoclonal antibody formulations.

中文翻译：

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聚山梨酯20 HP和80 HP水溶液的表面张力和自缔合特性：蛋白质稳定机制的见解

目的

聚山梨酯20和80是开发肠胃外蛋白质制剂最常用的表面活性剂，因为它们有益的安全性和稳定性。尽管显示出优异的稳定特性，但是这些表面活性剂用于水性蛋白质制剂的稳定机理仍然不清楚。文献中已经讨论了不同的稳定模型，其中可能形成蛋白质表面活性剂胶束复合物。

方法

这项研究的重点是确定相对于形成的胶束尺寸（通过动态光散射，DLS），浓缩级聚山梨酯20 HP（PS 20 HP）和聚山梨酯80 HP（PS 80 HP）的自缔合特性表面活性剂分子在其上自缔合（cmr，临界胶束浓度范围）形成胶束，并产生相关的表面张力。测定表面张力和胶束大小与温度以及制剂组成（缓冲盐的存在和离子强度的影响）的关系。

结果

对于PS 20 HP，在25°C时的临界胶束浓度范围值（cmr）在15–75μM之间，而对于PS 7 HP的7–16μM，其临界胶束浓度范围值（cmr）则要低得多，这仅取决于配方组成。随着温度升高，cmr会略有下降。与PS 20 HP（R _h = 3.5 nm）（25°C）相比，PS 80 HP形成较大的胶束（R _h = 4.5 nm ）。对于PS 80 HP，胶束尺寸的温度依赖性更为明显。

结论

基于这些结果，对通过抗体-聚山梨醇酯胶束复合物的形成而提出的稳定机制，特别是抗体制剂，进行了严格的讨论，当前的研究表明，对于常用的单克隆抗体制剂，这种稳定机制不太可能。