人血浆中铂(Pt)的未结合部分的定量对于评估化疗药物顺铂的药代动力学是重要的。在这项研究中,我们试图将使用Nanosep®过滤器的未结合Pt的回收率与1)传统过滤器(Centrifree®,Centrisart®,Amicon®)或三氯乙酸(TCA)蛋白沉淀,and2)unbound,绑定,和临床标本中的总Pt浓度。对于测试的过滤器,1)分子量截止值的影响,2)离心力,和3)评估人血浆中Pt结合的总Pt浓度。使用电感耦合等离子体质谱法定量Pt。在添加0.9μg/mLPt的人血浆中,未结合的Pt的百分比在较高的离心速度下增加。相比之下,在TCA蛋白沉淀后,未结合的Pt的百分比最高(42.1%)。当总Pt≤0.9μg/mL时,未结合的Pt(~20-30%)在过滤器中是一致的。相反,当血浆中添加超过0.9μg/mL的Pt时,使用超滤,未结合的Pt的百分比从36.5%增加到48%,与TCA沉淀的63.4%至79%相比。在接受含顺铂化疗的患者中,在浓度超过0.9μg/mL时,未结合的Pt的分数在35%至90%之间。此外,血浆中未结合的Pt分数与未结合的Pt浓度(R2=0.738)和总Pt浓度(R2=0.335)相关。总之,这项研究表明,1)未结合铂的百分比受体外和临床标本中总铂和未结合铂水平的影响,和2)使用Nanosep®过滤器的超滤是定量人血浆中未结合的Pt浓度的可行方法。
Quantification of the unbound portion of platinum (Pt) in human plasma is important for assessing the pharmacokinetics of the chemotherapeutic drug cisplatin. In this study, we sought to compare the recovery of unbound Pt using Nanosep® filters to 1) traditional filters (Centrifree®, Centrisart®, Amicon®) or trichloroacetic acid (TCA) protein precipitation, and 2) unbound, bound, and total Pt concentrations in clinical specimens. For the tested filters, the impact of 1) molecular weight cut-offs, 2) centrifugation force, and 3) total Pt concentration on Pt binding in human plasma was evaluated. Pt was quantified using inductively coupled-plasma mass spectrometry. In human plasma spiked with 0.9 μg/mL Pt, the percent of unbound Pt increased at higher centrifugation speeds. By comparison, the percent of unbound Pt was highest (42.1%) following TCA protein precipitation. When total Pt was ≤0.9 μg/mL, unbound Pt (∼20-30%) was consistent across filters. Conversely, when plasma was spiked with Pt exceeding 0.9 μg/mL, the percent of unbound Pt increased from 36.5 to 48% using
ultrafiltration, compared to 63.4% to 79% with TCA precipitation. In patients receiving cisplatin-containing chemotherapy, the fraction of unbound Pt at concentrations exceeding 0.9 μg/mL ranged between 35 and 90%. Moreover, the unbound fraction of Pt in plasma correlated with the concentration of unbound (R2 = 0.738) and total Pt (R2 = 0.335). In summary, this study demonstrates that 1) the percent of unbound Pt is influenced by total and unbound Pt levels in vitro and in clinical specimens, and 2)
ultrafiltration with Nanosep® filters is a feasible method for quantifying unbound Pt concentrations in human plasma.