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Solid phase preparations of 99m Tc labeled radiopharmaceuticals
Author(s) -
Rao Ponugoti S.,
Li Hongyu,
Reddy Kishan C.,
Thakur Mathew L.
Publication year - 2002
Publication title -
journal of labelled compounds and radiopharmaceuticals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.432
H-Index - 47
eISSN - 1099-1344
pISSN - 0362-4803
DOI - 10.1002/jlcr.550
Subject(s) - chemistry , matrix (chemical analysis) , valency , colloid , reducing agent , nuclear chemistry , radiochemistry , vial , chromatography , tin , organic chemistry , philosophy , linguistics
For the preparation of most 99m Tc radiopharmaceuticals, SnCl 2 has remained the agent of choice for reduction of Tc 7+ to lower valency states, which facilitates its chelation by compounds of diagnostic importance. We have developed a simple technique in which SnCl 2 lyophilized in a glass vial, either alone or on a solid matrix of polymeric microspheres (beads), was used. Tin‐113 ( t 1/2 – 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 99m Tc‐ labeled peptides, in which SnCl 2 was used as a reducing agent for radiolabeling, a procedure well established in our laboratory. Labeling efficiencies for all four peptides using SnCl 2 on solid phase was greater than 95%, as compared to less than 90% ( P =0.05) for SnCl 2 lyophilized without the solid matrix. Colloid formation was less than 3% in either case. The stability of SnCl 2 was greater than six months for solid matrix, and less for that without the microspheres. The 113 Sn measured as a daughter product 113m In indicated that release of SnCl 2 from microspheres in reaction mixture was 85±3%, as compared to 80±5% lyophilized alone. The recovery of 99m Tc in solution from microspheres was 95–100%. 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.