Distribution and excretion of lanthanides: comparison between europium salts and complexes

Abstract

Europium (152,154Eu) was intravenously injected into rats as: (i) the chloride salt at pH 7.4, (ii) the chloride salt at pH 3, (iii) the albumin complex and (iv) the DTPA complex, and tissue uptake was determined 24 h later. For the chlorides, the target organ for uptake was liver (about 60% of dose) whilst europium complexes were rapidly excreted in urine and were predominantly taken up into the kidney (about 0.5% of dose) and bone. Liver uptake of EuCl3, pH 7.4, corresponded to that of a colloidal material with most 152Eu present in the non-hepatocyte population; however, EuCl3, pH 3, was handled in a different manner, with significant uptake by hepatocytes. The differing tissue distributions of EuCl3 and Eu-albumin suggest that plasma albumin does not readily bind injected EuCl3. Renal uptake of europium, although a relatively low proportion of the injected dose, was associated with many subcellular fractions, including lysosomes, suggesting significant intracellular uptake and thus possible retention.

Systemically-delivered biodegradable PLGA alters gut microbiota and induces transcriptomic reprogramming in the liver in an obesity mouse model

“…This, coupled with an acute experiment involving bile duct ligation, by which we achieved experimental obstruction of the extrahepatic biliary system, allowed us to determine with a high degree of confidence that PLGA NPs and their degradation products accumulate in the lower GIT via the liver. Since europium complexes are eliminated through glomerular filtration in kidneys 33 , the europium fluorescence signal in the GIT is highly suggestive that at least a part of the PLGA polymer (or a portion of its non-degraded particles) is still attached to the europium label following hepatobiliary excretion. Even though there is currently a wide nano-scale range available, the nanoparticle size (100 nm) chosen in this study is commonly used in drug delivery research; most importantly, many investigators report off-target nanoparticle clearance by liver (> 80% of the injected dose in many cases), which is likely driven by the size of liver sinusoidal endothelial fenestrations, ranging from 100 to 150 nm 34 .…”

Lanthanide-based tools for the investigation of cellular environments

“…The salt was taken up by the liver, while the albumin complex was excreted rapidly into the urine, suggestive of a weak interaction between Eu 3+ and albumin in serum. 87 Intriguingly, La 2 (CO 3 ) 2 is a potential noncalcium phosphate binding drug. Its surprisingly low systemic toxicity is ascribed to its low solubility in physiological fluids.…”

The therapeutic application of lanthanides

“…Work sponsored by Johnson Matthey at the University of Surrey, UK, highlighted the ease with which the lanthanides formed precipitates with phosphate, frequently a challenge for the investigator. 29,30 In collaboration with Shire Pharmaceuticals a project was initiated to examine lanthanides as phosphate binders for hyperphosphatemia. In vitro phosphate binding studies comparing a number of lanthanide salts and complexes identified lanthanum carbonate as having good phosphate binding properties.…”