Decorporation of thorium-228 from the rat by 3,4,3-LIHOPO and DTPA after simulated wound contamination

1 With DTPA as a comparison, the siderophore analogue 3,4,3-LIHOPO has been examined for its ability to remove 228Th nitrate from the rat after subcutaneous (sc) and intramuscular (im) injection to simulate wound contamination. The commencement of treat ment was delayed 30 min, 6 h or 1 d and the animals killed at 7 d. 2 In all cases 3,4,3-LIHOPO was appreciably more effec tive than DTPA although the efficacy of treatment and the relative effectiveness of the ligands decreased rapidly with their delay in administration. 3 Optimum removal with both ligands occurred when initial local administration at 30 min after exposure was followed by repeated intraperitoneal injection at 6 h, 1, 2 and 3 d. Under these conditions the body con tent of 228Th was reduced to 20% of controls after sc injection and 15% after im injection. The correspond ing values using repeated DTPA administration were 80% and 54%. 4 It is concluded that 3,4,3-LIHOPO represents, poten tially, a considerable advance on DTPA, the current agent of choice for the treatment of wounds contami nated by 228Th.