游离125I与血浆蛋白的结合及其对血药浓度测定的影响

通过体内、外实验, 研究了游离125I与血浆蛋白的结合及其在三氯乙酸(TCA)沉淀后的沉淀百分率, 并与125I-RGD-Sak在SD大鼠中不同时间血药浓度的结果进行了比较. 结果表明, 游离125I能与血浆蛋白结合, 并为TCA所沉淀, 且在一定范围内, 游离125I与血浆蛋白结合后的沉淀百分率与温育时间及游离125I的活度无关. 体内、外实验中, 游离125I与血浆蛋白结合后的沉淀百分率分别为(1.26±0.14)%及(1.38±0.33)%. 沉淀物中含有吸附在沉淀物表面的游离125I, 该吸附需要用TCA沉淀2~3次才能去除. 采用125I核素示踪法进行生物类制品的药代动力学研究时, 应对游离125I的影响进行校正.

Influence of Ionic 125I Bound to Plasma Protein on Measurement of Labeled Drug Concentration in Blood

The aim of this study was to investigate the influence of ionic 125I on the results of pharmacokinetics study for biologic products. The ionic 125I bound to plasma protein was studied through measuring precipitation rates of plasma protein bound ionic 125I after TCA precipitation in vitro and in vivo, with which precipitation rates of 125I-RGD-Sak in plasma of SD rats at different time were compared. The results of the experiment show that ionic 125I could be bound to plasma protein and be deposited by TCAin vitro: (1.26±0.14)%; in vivo: (1.38±0.33)%]. The precipitation rates were independent of the reaction time(10 to 1440 min) and ionic 125I activity(14500 to 120000 count/min). Also, ionic 125I attached to the surface of precipitate contributed a lot to the precipitation rate, which could be eliminated after 2 to 3 times TCA precipitation. The influence of the ionic 125I should be calibrated in 125I tracing method applied to pharmacokinetics study for biological products.