Preparation of rhenium-188-tin colloid as a radiation synovectomy agent and comparison with rhenium-188-sulfur colloid

As a generator-produced beta-emitting radionuclide, the importance of Re-188 for radionuclide therapy is increasing rapidly. We prepared Re-188-tin colloid and compared its properties with Re-188-sulfur colloid. Labeling efficiencies reached >98% for tin colloid at 2 h and 89-94% for sulfur colloid at 3 h. All the preparations were stable for 72 h in water, serum, and synovial fluid. If labeled at higher temperature, the particle size of tin colloid increased. The residual radioactivity of Re-188-sulfur colloid in disposable polypropylene syringes after injecting mice was high (62.0 +/- 7.0%) due to its hydrophobic nature, while that of Re-188-tin colloid was low (2.9 +/- 1.6%). Although both Re-188-tin colloid and Re-188-sulfur colloid might be useful for radionuclide therapy, we conclude that Re-188-tin colloid is more advantageous over Re-188-sulfur colloid, due to higher labeling efficiency, control of the particle size, and lower residual activity in the injection syringes. (C) 2000 Elsevier Science Ltd. All rights reserved.