Technetium Tagged Radiopharmaceuticals

Receptor Specific Agents-technetium Tagged Radiopharmaceuticals... 

Radiopharmaceutical formulations based on "mTc may be divided into two major classes.635 The Class I formulations include what may be described as technetium tagged materials. These may be particles such as cells or colloidal substances, or they may be molecular species such as proteins or other large biological molecules. The essential feature of these agents is that their biodistribution behaviour is determined by the nature of the substrate material. Thus the attachment of a "mTc label should have little or no effect on their biodistribution. However, it cannot necessarily be assumed that this will be the case, especially when relatively low molecular weight substrates are involved. 

Tc pharmaceuticals based on coordination complexes with functionalized ligands are also known as Tc essentials those concerning labeled particles and macromolecules are called Tc-tagged radiopharmaceuticals. A variety of chelating agents have been developed for complex formation with certain oxidation states of technetium, providing the structural requirements for uptake and retention (Schwochau 2000). Examples of Tc essentials are shown in Fig. 2.3.1. 

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