Synthesis and evaluation of [11C]cyanoimipramine

[11C]Cyanoimipramine has been prepared by methylation of the desmethyl cyanoimipramine with [11C]methyl iodide. The chemically and radiochemically pure labelled product was obtained with a high specific activity (> 300 mCi/μmol). When 11C (or 3H)-cyanoimipramine was intravenously administered in mice, high accumulations were shown in brain and lung. The regional distribution of radioactivity in the rat brain 30 min after i.v. injection of [11C]cyanoimipramine showed that the radioactivity was high in receptor rich areas (striatum, cerebral cortex etc.) but low in receptor poor area (cerebellum). The in vivo stability of [3H]cyanoimipramine was quite stable in the mouse brain for at least 30 min. Thirty minutes after injection, the radioactivity in the cerebral cortex of the carrier-added state was reduced as compared with the carrier-free state. Taken together, the in vivo specific binding of [3H]cyanoimipramine in the cerebral cortex was estimated at about 40-50% of the total radioactivity. Furthermore, the distribution of [3H]cyanoimipramine in the mice forced to swim was examined. Significant changes in the distribution of [3H]cyanoimipramine were observed in the cerebral cortex. (author)