A kit formulation for the labelling of lipiodol with generator-produced 188Re

A lyophilised kit formulation for the efficient labelling of lipiodol with generator-produced Re-188 is described. This method involves the reaction of [(ReO4)-Re-188-O-VII](-) (37-370 MBq) with SnCl2 as a reducing agent, potassium oxalate as a reduction promoter, ascorbic acid as antioxidant and sodium gluconate as a weak chelate. The intermediate compound Na[(ReO)-Re-188-O-V(gluc)(2)] reacts with the sodium salt of a dithiobenzoate ligand to give the neutral complex [(118)Re(III)n(PhCS3)(2)(PhCS2)]. This complex is then quantitatively extracted with lipiodol to afford a stable solution. Radiochemical purity (RCP) was greater than 90% and the yield of extraction was about 88%. The role of the different kit components has been studied in detail to find the most efficient formulation (amount of reducing agent, antioxidant). The use of 0.8 mg of stannous chloride, with 40 mg of potassium oxalate and 30 mg of ascorbic acid, was found necessary. The stability of the Re-188-radiolabelled lipiodol has been investigated, in the presence of plasma. The radiolabelled lipiodol (Re-188-SSS lipiodol) is stable at least 48 h (RCP = 91.0 +/- 4.0%). Copyright (C) 2004 John Wiley Sons, Ltd.