COMPARATIVE EFFICACIES OF 3,4,3-LIHOPO AND DTPA FOR ENHANCING THE EXCRETION OF PLUTONIUM AND AMERICIUM FROM THE RAT AFTER SIMULATED WOUND CONTAMINATION AS NITRATES

With DTPA as a comparison, the siderophore analogue 3,4,3-LIHOPO has b een examined for its ability to remove Pu-238 and Am-241 from the rat after subcutaneous (s.c.) and intramuscular (i.m.) injection of about 200 Bq of each actinide (0.3 ng Pu, 1.6 ng Am). After the s.c. deposit ion of Pu-238 and Am-241, both ligands were more effective after local administration than (in decreasing order) their repeated interperiton eal (i.p.) injection, single i.p. injection and continuous infusion. D osages of 3 mumol kg-1 of 3,4,3,-LIHOPO were at least as effective as 30 mumol kg-1 DTPA after each mode of administration. The most effecti ve regimen of those investigated for s.c. Pu-238 and Am-241 involved l ocal administration of 30 mumol kg-1 of 3,4,3-LIHOPO at 30 min followe d by i.p. injections at 6 h, 1, 2 and 3 day. By day 7 after exposure, the amounts of Pu-238 and Am-241 retained in the body were 2 and 7% of those in controls, respectively and 10 and four times less than when DTPA was administered using the same regimen. The ligand 3,4,3-LIHOPO was more effective for Pu-238 and Am-241 after their i.m. injection. T his was attributed to the greater retention of these actinides at the wound site (97 versus 67%) when treatment commenced. After a single lo cal injection of 30 mumol kg-1 at 30 min, the amounts of Pu-238 and Am -241 retained in the body at 7 day were 0.9 and 0.8% of controls. Thes e values were 34 and 27 times less than after local and repeated i.p. injections of DTPA at dosages of 30 mumol kg-1. It is concluded that t he administration of 3,4,3-LIHOPO represents potentially a most signif icant advance in the treatment of wound contamination by Pu-238 and Am -241 by chelating agents.