Biodistribution and excretion of 153Gd-labeled gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid following repeated intravenous administration to rats.
OBJECTIVE
We investigated the distribution of radioactivity in tissues and organs and its disappearance following repeated intravenous (i.v.) administration of 153Gd-labeled gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) to rats.


METHODS
A high total dose of 250 mumol/kg of 153Gd-labeled Gd-EOB-DTPA (a daily injection of 50 mumol/kg is equivalent to 92.5 kBq per animal on 5 consecutive days) was given to conscious rats by fast i.v. injection via a tail vein. The organ distribution and the body elimination into urine and feces were investigated at time points 3, 7, 14, and 21 days following the last injection; five animals were used at each time point. All samples were measured by gamma counting of 153Gd over a 10-min period.


RESULTS
The radioactivity quickly disappeared from the body, mostly through feces. In the liver, no radioactivity could be detected at 3 days postinjection. At 21 days postinjection, only 0.002% of the gadolinium injected was detected, the vast majority (approximately 95%) of which was found in the kidneys.


CONCLUSIONS
After repeated i.v. administration of a total dose of 250 mumol/kg of 153Gd-labeled Gd-EOB-DTPA, the elimination from the body was found to be 99.998% complete. Only negligible long-term retention of radioactive gadolinium was observed despite the relatively high dose injected. No perceptible evidence for decomplexation of Gd-EOB-DTPA could be found.
Mühler
A
A
Research Laboratories of Schering AG, Berlin, Germany.
Weinmann
H J
HJ
D000818:Animals; D003287:Contrast Media / Q000493:pharmacokinetics*; D005682:Gadolinium / Q000493:pharmacokinetics; D019786:Gadolinium DTPA / Q000493:pharmacokinetics*; D007262:Infusions, Intravenous; D008099:Liver / Q000378:metabolism*; D008297:Male; D011868:Radioisotopes / Q000493:pharmacokinetics; D051381:Rats; D017208:Rats, Wistar; D014018:Tissue Distribution
D003287:Contrast Media; D011868:Radioisotopes; C073590:gadolinium ethoxybenzyl DTPA; D005682:Gadolinium; D019786:Gadolinium DTPA