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 188Re for radionuclide therapy is increasing rapidly. We prepared 188Re-tin colloid and compared its properties with 188Re-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 188Re-sulfur colloid in disposable polypropylene syringes after injecting mice was high (62.0+/-7.0%) due to its hydrophobic nature, while that of 188Re-tin colloid was low (2.9+/-1.6%). Although both 188Re-tin colloid and 188Re-sulfur colloid might be useful for radionuclide therapy, we conclude that 188Re tin colloid is more advantageous over 188Re sulfur colloid, due to higher labeling efficiency, control of the particle size, and lower residual activity in the injection syringes.