Improved freeze-dried kit for the preparation of 188 ReN-DEDC/lipiodol for the therapy of unresectable hepatocellular carcinoma.

Rhenium-188-N-(DEDC)2 /lipiodol (abbreviated as 188 ReN-DEDC, where DEDC = monoanionic diethyldithiocarbamate) is a clinically proven radiopharmaceutical for the therapy of unresectable hepatocellular carcinoma (HCC) through trans arterial radioembolization (TARE). A two-vial freeze-dried kit for the preparation of [188 ReN(DEDC)2 ] complex using sodium perrhenate (Na188 ReO4 ) obtained from a commercial Tungsten-188/Rhenium-188 generator had been reported earlier. This method required addition of stipulated volume of glacial acetic acid into vial 1 by the user for efficient preparation of [188 ReN]2+ intermediate. An error in this step can result in low radiochemical yield of [188 ReN]2+ intermediate as well as sub-optimal pH of the reaction mixture for the second step, leading to poor radiochemical purity of 188 ReN-DEDC complex. In the present work, a solution to this problem was found by including an oxalate buffer of pH = 3 in vial 1, eliminating the need for the addition of glacial acetic acid by the user. This modification not only made the kits more user-friendly, it resulted in significant improvement in the kinetics of formation of [188 ReN]2+ intermediate, wherein > 95% radiochemical purity could be achieved within 5 min incubation at ambient temperature. Moreover, the novel route for the preparation of [188 ReN]2+ intermediate may be applied to any radiopharmaceutical based on 188 ReN-core.