Synthesis and biological evaluation of Tc-99m- cyclopentadienyltricarbonyltechnetium-labeled octreotide

Todd W. Spradau, W. Barry Edwards, Carolyn J. Anderson, Michael J. Welch, John A. Katzenellenbogen

Research output: Contribution to journalArticlepeer-review


Octreotide was labeled at its N-terminus with Tc-99m- cyclopentadienyltricarbonyltechnetium, and the biodistribution of the labeled conjugate was studied in adult female Sprague-Dawley rats. The synthesis began with the preparation of Tc-99m-(methoxycarbonylcyclopentadienyl) tricarbonyltechnetium from Tc-99m-pertechnetate using a novel double ligand transfer reaction; it was completed in a total of five steps, with an 8% overall radiochemical yield (15% decay-corrected). The 99mTc- cyclopentadienyltricarbonyltechnetium-labeled octreotide conjugate (99mTc- CpTT-octreotide) showed receptor-mediated uptake in the pancreas and adrenals, which was blocked (80% and 93%, respectively) by excess unlabeled octreotide. These studies illustrate a new method for labeling a peptide with Tc-99m through an organometallic linkage that is stable, nonpolar, and low molecular weight; it complements labeling approaches that utilize inorganic metal complexes.

Original languageEnglish (US)
Pages (from-to)1-7
Number of pages7
JournalNuclear Medicine and Biology
Issue number1
StatePublished - Jan 1999


  • Cyclopentadienyltricarbonyltechnetium
  • Double ligand transfer
  • Octreotide
  • Somatostatin
  • Technetium- 99m

ASJC Scopus subject areas

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


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