Potential Ho-166 radiopharmaceuticals for intravascular radiation therapy (IVRT)-I : [Ho-166] holmium labeled ethylene dicysteine

The use of beta (-) emitting radionuclides in the control of restenosis in post angioplasty patients is currently under intense investigation at many leading cardiovascular research centers. P-32 coated metallic stents, Ir-19 2 wire source and balloons filled with an appropriate radionuclide solution such as of Re-188, attached to catheter are being studied. Ho-166 has comp arable radionuclidic properties to that of Re-188, can be more easily produ ced and hence is an attractive alternative to Re-188. Ethylene dicysteine c omplex of Ho-166 was prepared and its pharmacological behavior studied. Opt imum conditions for the preparation of complex with respect to the reaction time, ligand concentration, pH of the reaction mixture as well as reaction temperature were standardized. The stability of the labeled complex at roo m temperature as well as at 4 degreesC was determined. Biodistribution patt ern of the injected complex in Wistar rats was estimated at 10 min, 30 min and 3 h post injection. This study indicated that >90% of the injected Ho-1 66-EC complex was excreted in urine within 3 h post injection, with insigni ficant retention in any major organ. These studies reveal that Ho-166-EC co uld be a viable substitute for Re-188 compounds in radioactive liquid-fille d balloon IVRT. (C) 2001 Elsevier Science Inc. All rights reserved.