Structure-distribution relationships of radiopharmaceuticals. Correlation between the reversed-phase capacity factors for Tc-99m phenylcarbamoylmethyliminodiacetic acids and their renal elimination.

Capacity factors (k') have been obtained for twenty-eight different phenyl substituted phenylcarbamoylmethyliminodiacetic acids (HIDAs) using reversed-phase high-performance liquid chromatography (HPLC). They have been shown to be a useful measure of the lipophilicity of the ligands and their technetium-99m complexes. When k' for the ligands or log Poct for the Tc-99m complexes was plotted against theoretical lipophilicity, three groups of HIDAs were observed. The membership of each group is determined by the degree of ortho substitution. The effect of lipophilicity on protein binding allows the use of ligand capacity factors to predict the routes of elimination of various Tc-HIDAs.