Labeling of tributylstannyl Iomazenil with Radioiodine using Different Oxidizing Agents

Benzodiazepine receptor tracer (I125) iomazenil (Ro 16-0154, I M Z) was prepared by the reaction of its tributylstannyl precursor (I M-Sn Bu3) with Na125 in the presence of different oxidizing agents such as lactoperoxidase, chloramine-T and iodogen amount. The effects of different reaction parameters such as temperature, reaction time, oxidizing agent concentration, Ph and substrate concentration. Also the stability of the labeled product has been investigated. Chromatographic analysis of the reaction mixture by TLC using ethanol:ethylacetate (1:1) and by HPLC using methanol : water (55:45) as eluent showed that the optimum radiochemical yield of the final product is 94% and the radiochemical purity is 99%. Also HPLC chromatographic analysis indicated that the undesired side products especially the chlorinated products in case of chloramine-T is greater than that in case of other oxidizing agents It's found that, in case of using lactoperoxidase method, minimum undesired side products were produced, therefore high radiochemical purity was produced