Chemical fate of the nicotinic acetylcholinergic radiotracer [123I]5-IA-85380 in baboon brain and plasma

Ronald M. Baldwin, Sami S. Zoghbi, Julie K. Staley, Eric Brenner, Mohammed S. Al-Tikriti, Louis Amici, Masahiro Fujita, Robert B. Innis, Gilles Tamagnan

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


The fate of the nicotinic acetylcholinergic receptor radiotracer [123I]5-IA-85380 ([123I]5-IA) was studied in baboon by analyzing the chemical composition of brain tissue and plasma after intravenous administration of the tracer. Acetonitrile denaturation and high-performance liquid chromatography (HPLC) analysis showed predominantly unchanged (91-98%) parent tracer in all brain tissues examined, compared to significant metabolism (23% parent) in the plasma at 90 min postinjection, and control tissue recovery of 95-98%. [123I]5-IA was distributed to the thalamus with a standardized uptake value of 9.2 (0.04% dose/g) or a concentration 5.8 times higher than that of the cerebellum. The HPLC behavior of a synthesized sample of one hypothesized metabolite, 5-iodo-3-pyridinol (5-IP), was consistent with plasma radiometabolite fraction. Since only parent radiotracer compound was found in brain tissue, these results add confidence that information derived from single photon emission computed tomography images of 123I activity in the brain after [123I]5-IA administration can be interpreted as distribution of an intact radiotracer.

Original languageEnglish (US)
Pages (from-to)549-554
Number of pages6
JournalNuclear Medicine and Biology
Issue number4
StatePublished - May 2006


  • (S)-5-[I]iodo-3-(2-azetidinylmethoxy)pyridine
  • 5-iodo-3-pyridinol
  • Metabolites
  • Nicotinic acetylcholine receptor
  • Pharmacokinetics
  • SPECT tracer validation
  • [I]5-IA-85380

ASJC Scopus subject areas

  • Molecular Medicine
  • Radiology Nuclear Medicine and imaging
  • Cancer Research


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