Zäh Maximilian, Brandenbusch Christoph, Groël Sebastian, Winter Gerhard, Sadowski Gabriele
Laboratory of Thermodynamics, Department of Biochemical and Chemical Engineering, TU Dortmund University, Emil-Figge-Street 70, Dortmund 44227, Germany.
Department of Pharmacy, LMU Munich, Chair of Pharmaceutical Technology and Biopharmaceutics, Butenandtstr. 5, Munich 81377, Germany.
Mol Pharm. 2025 Feb 3;22(2):918-926. doi: 10.1021/acs.molpharmaceut.4c01106. Epub 2025 Jan 14.
Lyophilization remains a key method for preserving sensitive biopharmaceuticals such as monoclonal antibodies. Traditionally, stabilization mechanisms have been explained by vitrification, which minimizes molecular mobility in the lyophilized cake, and water replacement, which restores molecular interactions disrupted by water removal. This study proposes a novel design strategy that combines water activity and glass-transition temperature as the main indicators to predict long-term stability in lyophilized formulations. The water activity, calculated as the product of water activity coefficient and (residual) water content, serves as a mutual indicator of molecular interactions and influence of residual water content in the lyophilizate. By predicting beneficial excipient combinations through activity coefficient calculations using the perturbed-chain statistical association fluid theory model and calculating using the Gordon-Taylor equation, the study identifies favorable excipient systems, such as sucrose/ectoine mixtures, providing formulation windows that offer broad stability ranges. The approach was validated with stability studies, confirming that formulations within a water activity range of 0.025-0.25 exhibit high (long-term) stability. This work advances formulation development by integrating water-excipient interactions and residual moisture content into a predictive model, moving beyond traditional empirical methods and offering a robust pathway to the design of stable biopharmaceutical formulations. This makes it possible to achieve high/favorable water activities despite low residual moisture (thus, high glass-transition temperatures) with plausible excipient concentrations and combinations.
冻干仍然是保存单克隆抗体等敏感生物药物的关键方法。传统上，稳定机制可以通过玻璃化作用来解释，玻璃化作用可使冻干饼中的分子流动性降至最低，以及通过水置换来解释，水置换可恢复因水分去除而破坏的分子相互作用。本研究提出了一种新颖的设计策略，该策略将水分活度和玻璃化转变温度作为主要指标，以预测冻干制剂的长期稳定性。水分活度通过水分活度系数与（残余）水分含量的乘积计算得出，它是分子相互作用以及冻干物中残余水分含量影响的共同指标。通过使用扰动链统计缔合流体理论模型通过活度系数计算预测有益的辅料组合，并使用戈登-泰勒方程进行计算，该研究确定了有利的辅料体系，如蔗糖/依克多因混合物，提供了具有广泛稳定性范围的制剂窗口。该方法通过稳定性研究得到验证，证实水分活度在0.025 - 0.25范围内的制剂表现出高（长期）稳定性。这项工作通过将水-辅料相互作用和残余水分含量整合到一个预测模型中，推动了制剂开发，超越了传统的经验方法，并为设计稳定的生物药物制剂提供了一条可靠的途径。这使得在残留水分含量较低（因此玻璃化转变温度较高）的情况下，通过合理的辅料浓度和组合实现高/有利的水分活度成为可能。
