Synthesis of 11C-labeled desipramine and its metabolite 2-hydroxydesipramine: potential radiotracers for PET studies of the norepinephrine transporter.

The antidepressant desipramine (DMI) and its principal metabolite 2-hydroxydesipramine (HDMI) have been radiolabeled with 11C for PET studies. The normethyl precursors of DMI and HDMI were synthesized from iminodibenzyl in 35% and 11% overall yield, respectively. Direct methylation of the normethyl precursor with [11C]CH3I, followed by HPLC purification, provided [11C]DMI and [11C]HDMI in 18-30% and 15-23% decay-corrected radiochemical yields, respectively, in a 45 min synthesis time from end of bombardment. The specific activities of the two radiotracers were >1459 Ci/mmol at the end of synthesis. [11C]DMI and [11C]HDMI have potential utility as PET radiotracers for the norepinephrine transporter.