PREPARATION OF [I-125] 3H2-LOPIPERIDOL-A BY EXCHANGE RADIOIODINATION

Preparation of radiolabeled peridinyl)-2,4,6-triiodo-1,3-benzenedicarb oxamide, ([I-125]-3H(2-iopiperidol-A), a nonionic radiographic contras t agent, was achieved by HAuCl4 mediated exchange radioiodination. [I- 125]-lopiperidol-A was isolated by reversed-phase HPLC in 83% radioche mical yield. The radiochemical purity of isolated [I-125]-3H2-iopiperi dol-A was 98.7% and the specific activity was 6.6 mCi/mu mol. The role of HAuCl4 in facilitating exchange radioiodination of 3H2-iopiperidol -A, however, appears to be a complex process not limited to the produc tion of electrophilic iodine ion.