Baek Youngbin, Yang Deyu, Singh Nripen, Arunkumar Abhiram, Ghose Sanchayita, Li Zheng Jian, Zydney Andrew L
Dept. of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802.
Product Development, Bristol-Myers Squibb, Devens, MA, 01434.
Biotechnol Prog. 2017 Nov;33(6):1555-1560. doi: 10.1002/btpr.2544. Epub 2017 Sep 4.
Diafiltration is used for final formulation of essentially all biotherapeutics. Several studies have demonstrated that buffer/excipient concentrations in the final diafiltered product can be different than that in the diafiltration buffer due to interactions between buffer species and the protein product. However, recent work in our lab has shown variations in solution pH that are largely independent of the protein concentration during the first few diavolumes. Our hypothesis is that these pH variations are due to nonidealities in the acid-base equilibrium coefficient. A model was developed for the diafiltration process accounting for the ionic strength dependence of the pK . Experimental results obtained using phosphate and histidine buffers were in excellent agreement with model predictions. A decrease in ionic strength leads to an increase in the pK for the phosphate buffer, causing a shift in the solution pH, even under conditions where the initial feed and the diafiltration buffer are at the same pH. This effect could be eliminated by matching the ionic strength of the feed and diafiltration buffer. The experimental data and model provide new insights into the factors controlling the pH profile during diafiltration processes. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1555-1560, 2017.
渗滤用于基本上所有生物治疗药物的最终制剂。多项研究表明，由于缓冲液成分与蛋白质产品之间的相互作用，最终渗滤产物中的缓冲液/辅料浓度可能与渗滤缓冲液中的不同。然而，我们实验室最近的工作表明，在最初的几个渗滤体积期间，溶液pH值的变化在很大程度上与蛋白质浓度无关。我们的假设是，这些pH值变化是由于酸碱平衡系数的非理想性。针对渗滤过程开发了一个模型，该模型考虑了pK对离子强度的依赖性。使用磷酸盐和组氨酸缓冲液获得的实验结果与模型预测非常吻合。离子强度的降低会导致磷酸盐缓冲液的pK增加，从而导致溶液pH值发生变化，即使在初始进料和渗滤缓冲液处于相同pH值的条件下也是如此。通过使进料和渗滤缓冲液的离子强度匹配，可以消除这种影响。实验数据和模型为控制渗滤过程中pH值分布的因素提供了新的见解。©2017美国化学工程师学会生物技术进展，33:1555 - 1560，2017。
