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Preparation and Examination of Labelled Stereoisomers in Vivo by Pet

  • Christer Halldin
  • Tetsuya Suhara
  • Lars Farde
  • Göran Sedvall

Abstract

The preparation and PET-examination of radiolabeled stereoisomers following administration i.v. are discussed as an approach for radioligand development. Stereospecificity has been demonstrated for drug binding to plasma proteins. Active transport across membranes is also sterospecific, whereas diffusion is related to lipophilicity which like other physicochemical properties is identical for an enatiomeric pair. Of major importance is that stereospecificity is a basic criterion on specific binding to a receptor, an enzyme or a transport mechanism. The enantiomer with specific binding should have a higher accumulation in a target region in vivo than that with no biochemical activity. Comparative PET studies with enantiomers have been suggested as a method to differentiate specific from nonspecific binding, which is the key problem in quantitative modeling. The usefulness of this method has been demonstrated by PET for several enantiomeric pairs and data regarding this topic with the enantiomers of the dopamine D-2 and D-l receptor antagonists [11C]raclopride and [11C]SCH 23390 are demonstrated in this communication. Another dopamine D-l receptor antagonist, [11C]SCH 39166, and one of its three inactive stereoisomers [11C]SCH 39165 are used together as an example where HPLC plasma metabolite analysis may demonstrate that stereoisomers can bind to plasma proteins differently. Data obtained with the enantiomers of other radiotracers for PET such as [11C]piquindone, [11C]deprenyl, [11C]nicotine and [11C]methionine are also reviewed.

Keywords

Positron Emission Tomography Positron Emission Tomography Study Methyl Iodide Ethyl Iodide Enantiomeric Pair 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer Science+Business Media New York 1995

Authors and Affiliations

  • Christer Halldin
    • 1
  • Tetsuya Suhara
    • 1
  • Lars Farde
    • 1
  • Göran Sedvall
    • 1
  1. 1.Department of Psychiatry and Psychology, Karolinska InstituteKarolinska HospitalStockholmSweden

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