SYNTHESIS OF 1-(TRANS-[I-123]IODOPROPEN-2-YL)-4- (4-CYANOPHENOXYMETHYL)PIPERIDINE - A SELECTIVE SIGMA-RECEPTOR RADIOLIGAND FOR SPECT

odopropen-2-yl)-4-(4-cyanophenoxymethyl)piperidine has been prepared a s a novel sigma receptor ligand for SPECT. This ligand was found to be selective in vitro for the sigma receptor site (Ki(sigma) = 21.7 nM) when tested in a variety of neuroreceptor binding assays. The lipophil icity of this ligand (log P-7.5 = 3.36) is appropriate for good brain uptake and relatively low non-specific binding. Radioiodination was ac complished using classical electrophilic iododestannylation methods an d specific activity of the purified product was > 2100 mCi/mu mole. Ra diochemical yields were 60-80% EOS and radiochemical purities were > 9 9%. The average time of synthesis and purification was 35 minutes.