名称:
Biodistribution and Imaging of 1-(2-Deoxy-β-D-Ribofuranosyl)-2,4-Difluoro-5-[123/125I]Iodobenzene (dRF[123/125I]IB), A Nonpolar Thymidine-Mimetic Nucleoside, in Rats and Tumor-Bearing Mice
摘要:
1-(2-Deoxy-beta-D-ribofuranosyl)-2,4-difluoro-5-iodobenzene (dRFIB) is a Putative bioisostere of iododeoxyuridine (IUdR). The advantages of dRFIB over IUdR for in vivo studies include resistance to both phosphorolytic cleavage of the nucleoside bond and de-iodination. dRFIB was radioiodinated (dRF(123/125)IB) by copper-catalyzed exchange using commercial sodium [I-123/125]iodide. The in vivo biodistribution of dRF[I-125]IB in BALBc mice and imaging of dRF[I-123]IB in Sprague-Dawley rats are reported. In vivo data for rats show rapid clearance of radioactivity from blood (> 95% LD in 15 minutes), extensive excretion in urine (56%ID/24 hours), concentration in the hepatobiliary-small intestine system and very little fecal excretion (similar to 3% ID/24 hours). Pharmacokinetic data for dRF[I-125]IB (i.v. 48.7 ug/kg) in rats (t(1/2)[h] = 0.51 +/- 0.14, AUC(inf)[mu g.min/mL] = 3.7 +/- 0.4, Cl[L/kg/h] = 0.75 +/- 0.12, Vss[L/kg] = 0.96 +/- 0.18) corfirm. previously reported dose-dependent pharmacokinetics. Scintigraphic images of rats dosed with dRF[I-123]I were compatible with rapid soft-tissue clearance and extensive accumulation of radioactivity in bladder/urine and liver/small intestine. In tumor bearing mice, thyroid and stomach radioactivity was indicative of moderate deiodination. An unidentified polar radioactive metabolite was detected in serum.