Radioiodinated 1-(diethylaminopropyl)-4-phenylpiperazine: a potential brain imaging agent.

The preparation of radioiodinated 1-(diethylaminopropyl)-4-phenylpiperazine, an analog of HIPDM, and its tissue distribution in rats are described. The precursor undergoes facile electrophilic radioiodination with radionuclides of iodine at the no-carrier-added level to give isolated yields in the 69-85% range. Biodistribution studies indicate that the radiochemical is well extracted by the brain (1.68-1.79% ID) and activity is substantially retained for 4 h (greater than 67%). Brain-to-blood ratios during the 0.25-4.0 h period were 15-23:1. The brain uptake and retention as well as the high brain-to-blood ratios suggest the potential use of this agent for regional cerebral blood flow imaging.