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 treatment 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 effective 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 content of ²²⁸Th was reduced to 20% of controls after sc injection and 15% after im injection. The corresponding values using repeated DTPA administration were 80% and 54%. 4 It is concluded that 3,4,3-LIHOPO represents, potentially, a considerable advance on DTPA, the current agent of choice for the treatment of wounds contaminated by ²²⁸Th.