Synthesis and biological distribution of radiolabeled ammineruthenium (III)-amino acid complexes as potential pancreatic imaging agents.
Meyer CD, Davis MA, Periana CJ.
Complexes of ammine[103Ru]ruthenium(III) with L-histidine, beta-(4-pyridyl)-alpha-alanine, and S-[beta-(4-pyridyl)ethyl]-L-cysteine were synthesized in low specific activity and evaluated in mice as potential radiodiagnostic agents for pancreatic imaging. The biological distribution of each complex was determined in normal mice at 15 min, 1 h, and 2 h following intravenous administration. All four complexes were rapidly cleared through the kidneys, with 50% of the injected dose concentrated in the urine within 15 min. None of the complexes showed a tendency to accumulate in any major organ. Major differences in distribution were found in lungs, heart, spleen, stomach, intestine, bone, and soft tissues. A significant relative difference in pancreatic uptake was observed. Only the beta-(4-pyridyl)-alpha-alanine complex exhibited pancreas to liver ratios significantly greater than 1. The pancreas to liver ratio of 17 was reached 1 h following injection of this ruthenium complex, which is considerably higher than commonly reported values of 2.5 for [75Se]selenomethionine. The beta-(4-pyridyl)-alpha-alanine complex is therefore a promising candidate for evaluation as a pancreatic imaging agent when labeled with cyclotron-produced ruthenium-97.