Biodistribution, pharmacokinetic and radiation dosimetry of 111In-DTPA hexa lactoside

Objectives 111In-DTPA hexa lactoside is a newly developed radiopharmaceutical which has a high affinity to ASGPR (asialoglycoprotein receptor) on the surfaces of hepatocytes. Thus, 111In-DTPA hexa lactoside can be used for evaluation of the hepatocytic function and the monitoring of liver disease progress. In the present study, We investigated the biodistribution and pharmacokinetic of 111In-DTPA hexa lactoside in mice and provide estimates of radiation doses in humans.

Methods 111In-DTPA hexa lactoside was prepared by reacting 111InCl3 with DTPA hexa lactoside with high radiochemical purity of ~95%. The biodistribution study was evaluated in healthy BALB/c mice at selected times after intravenous (tail vein) injection of 111In-DTPA hexa lactoside. The pharmacokinetic and radiation doses were projected on the basis of the organ residence times.

Results The largest amounts of radioactivity were taken up by the liver (73.0 ± 9.1 percentage injected dose at 3 min),with a half-life at α-phase of 2.6 h and a half-life at β-phase of 612 h, while all other organs showed relatively low radioactivity accumulation. 111In-DTPA hexa lactoside was cleared rapidly from the blood, with a half-life at α-phase of 0.12 min and a half-life at β-phase of 6.36 min, and mainly excreted through the renal system. The projected whole-body dose in humans adult of about 70 kg was 0.137 mSv/Bq. The radioactivity distributed mainly to the liver, lower large intestine, testes and uterus. The projected doses were 0.0115, 0.0272, 0.0279 and 0.0563 mSv/Bq using the tissue-weighting factors of the International Commission on Radiological Protection (ICRP), publications 60.

Conclusions 111In-DTPA hexa lactoside showed high uptake in liver, slower liver eliminate and rapid blood clearance. The further clinical measurements are needed for a more detailed estimation. The present studies suggest that 111In-DTPA hexa lactoside is a new potential radiopharmaceutical for liver function diagnosis