Synthesis and in vivo evaluation of a new fluorine-18 labeled dopamine D2 radioligand synthesis with benzofuran benzamide skeleton

✍ Scribed by Futoshi Takao; Shigeki Sasaki; Minoru Maeda; Toshimitsu Fukumura; Takashi Tahara; Kouji Masuda; Yuichi Ichiya

• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: French
• Weight: 314 KB
• Volume: 33
• Category: Article
• ISSN: 0022-2135
• DOI: 10.1002/jlcr.2580331204

✦ Synopsis

Abstract

N‐[(1‐Ethyl‐2‐pyrrolidinyl)methyl]‐5‐(2‐[^18^F]fluoroethyl)‐2,3‐dihydroben‐zofuran‐7‐carboxamide ([^18^F]5) was synthesized via nucleophilic substitution with K^18^F/Kryptofix222 complex in 5.4∼6.8% radiochemical yields with a specific activity of larger than 5.6 TBq/mmol (150 Ci/mmol) at the end of the 110 minutes synthetic period. Its in vivo affinity toward CNS dopamine D2 receptors was investigated using rats in order to evaluate as a radiotracer for the PET (positron emission tomography) study of the dopamine D2 receptors. In biodistribution experiments, [^18^F]5 exhibited striatal accumulation, although the whole brain radioactivity was cleared rapidly. The striatal/cerebellar radioactivity ratio, which corresponds to the ratio of a brain D2 receptor‐rich to poor region, gradually increased to about 12 at 60 minutes after the injection. The striatal uptake was inhibited with pretreated haloperidol, a dopamine D2 antagonist, indicating that the striatal accumulation was due to the specific binding with D2 receptors. Thus, [^18^F]5 appears to be a potential in vivo radiotracer for dopamine D2 receptors.