A new series of Tc-99m-labeled hepatobiliary tracers: N'-acyl- and N'-sulfonyl ethylenediamine-N,N-diacetic acids

Various Tc-99m-labeled N'-substituted derivatives of ethylenediamine-N,N-diacetic acid (EDDA) are evaluated as hepatobiliary imaging agents. N-substituted aromatic acyl and aromatic sulfonyl derivatives of EDDA, labeled with Tc-99m, were administered to rabbits and golden hamsters, and the distribution indicated clearance by the hepatobiliary system. N'-aromatic sulfonyl EDDAs were labeled with Tc-99m by the SnCl2 method with more than 99% yield. Clearance of Tc-99m-p-toluenesulfonyl EDDA from the blood and the liver was as rapid as that of TC-99m N-(2,6-diethylphenylcarbamoylmethyl)iminodiacetic acid (Tc-99m benzenesulfonyl EDDA lowered urinary excretion. It is concluded that the sulfonyl EDDAs provide a fruitful source for Tc-99m-labeled hepatobiliary radiopharmaceuticals.

Complex formed from 3-hydroxy-4-formylpyridine, glutamic acid, and technetium--a possible cholescintigraphic agent

In order to obtain a technetium-99m-labeled cholescintigraphic agent suitable for kit preparation, reactions of a variety of aromatic aldehydes, amino acids, and [99mTc] pertechnetate were examined under mild conditions. Aqueous solutions of the three reactants were heated in a boiling-water bath and the products analyzed by means of thin-layer chromatography for the formation of organic technetium complexes. 3-Hydroxy-4-formylpyridine (HFP) and 1-methyl-3-hydroxy-4-formylpyridinium chloride (N-Me-HFP) formed the complex with excellent yields, whereas 3-hydroxy-2-formylpyridine, 4-nitrosalicylaldehyde, salicylaldehyde, and isonicotinaldehyde did not. The complex is concluded to be the Tc-99m chelate of the Schiff base formed from the aldehyde and amino acbbits administered with the complex of HFP, glutamic acid and Tc-99m. The results indicate that it is promising as a cholescintigraphic agent.