ISSN:
1619-7089
Keywords:
Key words: Technetium-99m
;
Mixed-ligand complexes
;
Chemical stability
;
Reactivity in vivo and in vitro
;
Glutathione
;
Challenge experiments
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract. ”3+1” technetium-99m mixed-ligand complexes as relevant to the development of a third generation of 99mTc radiopharmaceuticals were investigated in vivo and in vitro in the blood of rats. Surprisingly, in whole blood the complexes, which proved to be stable in saline, PBS of pH 7.4 and in plasma, were converted into two radioactive, more hydrophilic metabolites. Small structural differences in the complex molecule have a profound influence on the rate of metabolism of the complexes. To obtain an understanding of this unexpected reactivity, transchelation reactions with glutathione (GSH) were hypothesized and this hypothesis substantiated by challenge experiments carried out with a series of 99mTc and analogous rhenium complexes and GSH. In vitro studies in human plasma, whole blood and erythrocytes also revealed conversion of the complexes, though, at a much slower rate. Structural parameters influencing the stability of the complexes and consequences for the radiopharmaceutical design are discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s002590050284
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