Synthesis and in vivo evaluation of 122I- and 131I-labelled iodoperidol, a potential agent for the tomographic assessment of cerebral perfusion.

Iodoperidol (IP), an iodinated analogue of the antipsychotic drug haloperiodol, was evaluated as a cerebral blood flow radiopharmaceutical for PET or SPECT. IP was labelled with 131I or 122I (76% beta +, t1/2 = 3.6 min) in greater than 75% radiochemical yield via electrophilic aromatic iododestannylation. [131I]IP showed high cerebral uptake (1.9% of injected dose after 5 min) and good brain retention for the rat, with very low blood levels (brain/blood ratio = 35 at 2 h post injection). PET imaging of a dog demonstrated that [122I]IP has high selectivity for brain localization and good retention, and indicates that this class of compounds holds promise for development as perfusion radiopharmaceuticals.