应用整体自显影定量技术开展的单多次给药后大鼠组织分布比较研究

Tissue distribution by quantitative whole body autoradiography after single and repeated administration in rats

目的:应用整体自显影定量技术(QWBA),比较单次和重复多次给药后大鼠体内的组织分布情况,以指导人体放射性物质平衡试验设计。方法:按15 mg·kg^(-1)剂量,分别灌胃给予雄性Long-Evans(LE)大鼠0,7和14次的非放射性标记药物VPS-01(qd) 24 h后单次灌胃给予100μCi/15 mg·kg^(-1)的[14C]VPS-01(分别定义为0+1,7+1和14+1给药组);于给予放射性标记药物后的3,24,168和504 h每组处死1只大鼠,收集尸体并立即冷冻。使用大型冰冻切片机(Leica CM3600 XP)切片,适当处理后使用磷显像技术获得切片中各组织和感兴趣区域的放射性强度。结果:采用3种不同方式给药后总放射性均广泛分布于各组织中,VPS-01和/或其相关代谢产物与黑色素存在结合的现象。与0+1给药组比,7+1给药组中大鼠各组织放射性浓度及暴露量均显著降低;据大鼠组织暴露量估算的人体单次口服[14C]VPS-01可给予的最大放射性剂量从61.6增加到611μCi。14+1给药组大鼠的组织放射性浓度和暴露量更低,但与7+1组无显著性差异。结论:具有组织共价结合导致体内消除缓慢的药物在物质平衡试验中易引起人体放射性暴露量高,如先重复给予受试者数次非放射性标记药物,待人体内达到稳态后单次给予14C-标记药物,可显著降低受试者辐射暴露、加大人体放射性剂量可选择范围并增加循环血液中放射性浓度而易于代谢产物的鉴定。

Objective: Tissue distribution after single and repeated doses in rats was compared by quantitative whole body autoradiography technique (QWBA) to guide the design of human radioactive mass balance study.Methods: Male Long Evans (LE) rats were given,by gavage,0,7 and 14 doses (once a day) of non-radiolabeled drug VPS-01,at 15 mg·kg^(-1),followed by a single dose of [14C]VPS-01 at 100 μCi/15 mg·kg^(-1),po,at 24 h post last non-radioactive dose (defined as 0 + 1,7 + 1 and 14 + 1 groups,respectively). And then,after 3,24,168 and 504 h of radiolabeled drug administration,one rat from each group was sacrificed and carcasses were collected and frozen immediately,followed by sliced using Leica CM3600XP. After proper treatment,the radioactivity level of each tissue and region of interest in the slices were obtained by phosphorus imaging technology. Results: The total radioactivity of VPS-01 and/or its related metabolites was observed bound to melanin. Compared with 0 + 1 group,the radiation concentration and exposure of rats in 7 + 1 group significantly reduced,and the maximum radiation dose of [14C]VPS-01 in humans could accordingly increase from 61. 6 μCi to 611 μCi. However,no significant difference of exposure was observed between 14 + 1 group and 7 + 1 group. Conclusion: Drugs with slow elimination due to tissue covalent binding are easy to result in high radiation exposure in the human body in the mass balance study. If the subjects are given non-radiolabeled drugs repeatedly for several times to reach a steady state in human body before a single dose of the 14C-drug is given,the radiation exposure of subjects can be significantly reduced,the optional range of human radiation dose can be increased,and the radioactivity in the circulating blood will be increased,facilitating metabolite identification.