Monoiodo-D-tyrosine, an artificial amino acid radiopharmaceutical for selective measurement of membrane amino acid transport in the pancreas.

Using 11C-labeled natural amino acids, the functional diagnosis of tissue metabolism has been actively studied. Our interest has been focused on developing a clinically available 123I-labeled artificial amino acid with a single metabolic function. For this study, [123I]3-iodo-D-tyrosine ([123I]D-MIT) was selected. In vitro and in vivo studies using 125I-labeled D-MIT indicated that it showed a high pancreatic accumulation, selective affinity for membrane active transport systems, and was stable against enzymatic deiodination. A canine scintigraphic study using 123I-labeled D-MIT and kinetic analysis showed that it behaved as an "artificial amino acid" radiopharmaceutical with selective membrane amino acid transport affinity in the pancreas.