[125]I-Spectramide: A novel benzamide displaying potent and selective effects at the D2 dopamine receptor

Patricia M. Sánchez-Roa, Dimitri E. Grigoriadis, Alan A. Wilson, John Sharkey, Robert F. Dannals, Victor L. Villemagne, Dean F. Wong, Henry N. Wagner, Michael J. Kuhar

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


The new substituted benzamide Spectramide, (N-[2-[4-iodobenzyl-N-methylamino]-2-methoxy-4-ethyl]-5-chloro-methylamine] benzamide) labelled with 125I was used as a potent and highly selective dopamine-D2 receptor antagonist in rat striatal homogenates for in vitro receptor binding. Kinetic experiments demonstrated the reversibility of the binding and the estimated Kd from saturation analysis was 25 pM, with a Bmax of 20 pmol/g of tissue. Competition studies showed that spectramide did not interact potently with the D1 or dopamine-uptake site. Drugs known to interact with other receptor systems were weak competitors of the binding, while binding was potently inhibited by other D2 antagonists, such as spiperone and eticlopride. These data indicate that Spectramide binds selectively and with high affinity to the dopamine D2 receptors, and may prove to be a useful tool for the study of these receptors in vivo using PET or SPECT.

Original languageEnglish (US)
Pages (from-to)1821-1829
Number of pages9
JournalLife Sciences
Issue number19
StatePublished - 1989

ASJC Scopus subject areas

  • General Biochemistry, Genetics and Molecular Biology
  • Pharmacology, Toxicology and Pharmaceutics(all)


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