| Abstrakt: |
For the preparation of most 99mTc radiopharmaceuticals, SnCl2 has remained the agent of choice for reduction of Tc7+ to lower valency states, which facilitates its chelation by compounds of diagnostic importance. We have developed a simple technique in which SnCl2 lyophilized in a glass vial, either alone or on a solid matrix of polymeric microspheres (beads), was used. Tin-113 (t1/2 115 d) was used as a tracer, which facilitated quantitative assessment of loss or release of tin in the reaction mixtures. The feasibility and efficacy of this technique were examined for preparations of four 99mTc- labeled peptides, in which SnCl2 was used as a reducing agent for radiolabeling, a procedure well established in our laboratory. Labeling efficiencies for all four peptides using SnCl2 on solid phase was greater than 95%, as compared to less than 90% (P=0.05) for SnCl2 lyophilized without the solid matrix. Colloid formation was less than 3% in either case. The stability of SnCl2 was greater than six months for solid matrix, and less for that without the microspheres. The 113Sn measured as a daughter product 113mIn indicated that release of SnCl2 from microspheres in reaction mixture was 85±3%, as compared to 80±5% lyophilized alone. The recovery of 99mTc in solution from microspheres was 95100%. The large size of the microspheres used (649 μm) eliminated the risk of drawing them through a needle in a syringe used for injection of a preparation. Copyright © 2002 John Wiley & Sons, Ltd. |
Plný text