聚乙二醇化重组人粒细胞集落刺激因子的药代动力学与组织分布研究

摘要

目的 研究聚乙二醇化重组人粒细胞集落刺激因子(PEG-rhG-CSF)在动物体内的药代动力学与组织分布.方法 猕猴给予不同剂量(30、100和300μg/kg)的PEG-rhG-CSF,酶联免疫吸附法(ELISA)测定猕猴血浆中PEG-rhG-CSF浓度;[(125)I]标记示踪法结合分子排阻色潜法观察PEG-rhG-CSF在Wistar大鼠各组织中的分布情况.结果 猕猴单次sc PEG-rhG-CSF后血药浓度及系统暴露随给药剂量呈非线性增加.低、中、高剂量组达峰时间(T(max))为6.67～12.00h,全身清除率(CL)顺序减小,药-时曲线下面积(AUC)与给药剂量不成正比.sc给药的绝对生物利用度为47.5%.与临床使用剂量的rhG-CSF(10μg/kg)相比,猕猴sc中剂量PEG-rhG-CSF后C(max)、AUC分别为(1671±357)林叭和(45 156±9407(μg·h)/L,均明显高于rhG-CSF组(P< 0.05); PEG-rhG-CSF组的T(1/2β)为(13±3)h,较rhG-CSF组的T(1/2β)(1.52±0.08)h显著增加(P< 0.05);而CL为(2.3±0.5)ml/(h·kg),较rhG-CSF组的CL(19.6±2.4)ml/(h·kg)显著降低(P< 0.01).大鼠sc[125I]PEG-rhG-CSF后血清、肾、肺等组织放射性较高,2h血清原形药物浓度达峰,肺、肠道、膀胱等组织在给药后分布较慢,8h放射性达峰值.尿液中主要为小分子[125I」降解代谢产物;未观察到药物与血浆蛋白的结合.结论 将rhG-CSF进行PEG化修饰可以显著降低系统清除率,延长体内半衰期,增加药物暴露,可达到长效目的.药物主要分布于血管床,并代谢为小分子从泌尿系统排泄,不易透过血脑屏障.%Objective To study the pharmaeokineties and tissue distribution of pegylated recombinant human granuloeyte colony-stimulating factor (PEG-rhG-CSF) in animals. Methods Rhesus monkeys were administered PEG-rhG-CSF at various doses (30, 100 and 300 μg/kg). Enzyme-linked immunosorbent assay (ELISA) was used to determine the concentrations of PEG-rhG-CSF in plasma of rhesus monkeys. [125I] labeled tracing methad combined with size exclusion chromatography method was utilized to investigate tissue distribution of PEG-rhC-CSF in Wistar rats. Results After Rhesus monkeys were given PEG-rhG-CSF by subcutaneous administration, the concentration and systemic exposure level in plasma increased as non-linear kinetics following with the dosage. The peak time (Tmax) was between 6.67-12.00 h. Among the groups of PEC-rhG-CSF 30, 100 and 300 μg/kg, the clearance (CL) decreased in turn, and area under curve (AUC) was out of direct proportion to the dosage. The absolute bioavailability was 47.5 ％ after sc administration. After given PEG-rhG-CSF 100 μg/kg, the maximum concentration (Cmax),AUC were(1671 ± 357)μg/L and(45156 ± 9407) (μg.h)/L, respectively, which were obviously higher than that of rhG-CSF group with clinical dosage 10 μg/kg (P＜ 0.05). Tv2β of PEG-rhG-CSF group was( 13 ± 3) h, which was significantly increased compared with that of rhG-CSF group which was( 1.52 ± 0.08) h (P＜ 0.05). Meanwhile, CL of PEG-rhG-CSF group was(2.3 ± 0.5) ml/(h·kg),which was significantly lower thall than of rhG-CSF group with (19.6 ± 24) ml/(h·kg) (P＜ 0.01). Total radioactivity in serum,kindey and lung was high in rats given [125I] PEG-rhG-CSF. The concentration of intact [125I] PEG-rhG-CSF in serum reached the maximum at 2h, while other tissues, like lung, stool in bowel and urinary bladder, were distributed slowly after administration, in which the radioactive concentrations arrived the maximum at 8 h. Micromolecular metabolites of [125I] PEG-rhG-CSF were mainly existed in the urine. The conjugation of drug and plasma protein was not observed. Conclusion rhG-CSF modified with PEG can decrease the systemic clearance, prolong the circulating half-life, elevate in vivo exposure level, achieve the purpose of prolonged action. The drug is mainly distributed over vascular bed and metabolized to micromolecnle excreting by urinary system. PEC-rhG-CSF is difficult to permeate through the blood-brain barrier.