New fluorine-substituted analogue of eticlopride with high affinity toward dopamine D2 receptors.

Aiming at the development of positron-emitting ligands with specific and high affinity toward dopamine D2 receptors in the central nervous system, we synthesized a new fluorinated eticlopride derivative. A fluorine atom was introduced at the C-4 position of the pyrrolidine ring of eticlopride, a dopamine D2 antagonist of the benzamide series. The in vitro binding affinity of this ligand toward the D2 receptor was found to be as potent as eticlopride, suggesting that the corresponding 18F-labelled compound may be useful as an in vivo radioligand for positron emission tomography.