Evaluation of ^99mTc-labeled iminodiacetic acid derivatives of substituted 2-aminopyrroles as hepatobiliary imaging agents I

N-(3-Cyano-4,5-dimethyl-2-pyrrylcarbamoylmethyl)iminodiacetic acid (IIa) and N-(3-cyano-4-methyl-5-benzyl-2-pyrrylcar-bamoylmethyl)iminodiacetic acid (IIb) were synthesized, labeled with technetium 99m, and compared with ^99mTc-labeled p-isopropylacet-anilidoiminodiacetic acid (I) for hepatobiliary activity in rats. All three compounds showed similar clearance of radioactivity from the blood. Comparison of the amount of radioactivity in various organs 1 hr after injection showed no significant difference between I and IIb. Compound IIa showed significantly less radioactivity in the GI tract and a higher amount in the kidneys and bladder.