Sm and In DTPA derivatives with high hepatic specificity: in vivo and in vitro studies

Two DTPA derivatives, a mono-amide derivative containing an iodinated synthon, DTPA-IOPsp (L ) and the ligand DTPA(BOM) 1 3 153 31 111 31 (BOM5benzyloxymethyl) (L ), radiolabelled with Sm and In , were studied as potential hepatospecific gamma scintigraphic 2 agents. In vivo studies with Wistar rats show that the main excretory pathway for all the chelates studied is the hepatobiliary system. The complexes of L show even greater hepatobiliary specificity than L , perhaps as a consequence of longer blood circulation times due to 2 1 153 31 111 31 31 their strong affinity towards HSA. The Sm chelates are also more hepatospecific than the corresponding In chelates. The La 31 1 and In chelates of L and L show some structural and dynamic differences in aqueous solution, as studied by H NMR spectroscopy. 1 2 31 31 While only two nona-coordinated isomers were observed for the La complexes with both ligands, its number is much larger in the In complexes, with both octaand hepta-coordinated species (with unbound side arms), as well as structural isomers for each coordination number.  2002 Elsevier Science Inc. All rights reserved.