title: In vivo use of a radioiodinated somatostatin analogue: dynamics, metabolism, and binding to somatostatin receptor-positive tumors in man.
abstract: Somatostatin analogues, labeled with gamma-emitting radionuclides, are of potential value in the localization of somatostatin receptor-positive tumors with gamma camera imaging. We investigated the application in man of a radioiodinated analogue of somatostatin, 123I-Tyr-3-octreotide, which has similar biologic characteristics as the native peptide. The radiopharmaceutical is cleared rapidly from the circulation (up to 85% of the dose after 10 min) mainly by the liver. Liver radioactivity is rapidly excreted into the biliary system. Until 3 hr after injection, radioactivity in the circulation is mainly in the form of 123I-Tyr-3-octreotide. Thereafter, plasma samples contain increasing proportions of free iodide. Similarly, during the first hours after injection, radioactivity in the urine exists mainly in the form of the unchanged peptide. Thereafter, a progressive increase in radioiodide excretion is observed, indicating degradation of the radiopharmaceutical in vivo. Fecal excretion of radioactivity amounts to only a few percent of the dose. The calculated median effective dose equivalent is comparable with values for applications of other 123I-radiopharmaceuticals (0.019 mSv/MBq).
authors.affiliation: Department of Nuclear Medicine, University Hospital Dijkzigt, Rotterdam, The Netherlands.
authors.forename: W H
authors.initials: WH
authors.lastname: Bakker
authors.forename: E P
authors.initials: EP
authors.lastname: Krenning
authors.forename: W A
authors.initials: WA
authors.lastname: Breeman
authors.forename: P P
authors.initials: PP
authors.lastname: Kooij
authors.forename: J C
authors.initials: JC
authors.lastname: Reubi
authors.forename: J W
authors.initials: JW
authors.lastname: Koper
authors.forename: M
authors.initials: M
authors.lastname: de Jong
authors.forename: J S
authors.initials: JS
authors.lastname: Laméris
authors.forename: T J
authors.initials: TJ
authors.lastname: Visser
authors.forename: S W
authors.initials: SW
authors.lastname: Lamberts
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D009369:Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism; D015282:Octreotide / Q000031:analogs & derivatives* / Q000378:metabolism; D011877:Radionuclide Imaging; D017981:Receptors, Neurotransmitter / Q000378:metabolism*; D017481:Receptors, Somatostatin
chemical_list: D007457:Iodine Radioisotopes; D017981:Receptors, Neurotransmitter; D017481:Receptors, Somatostatin; C045210:3-Tyr-octreotide; D015282:Octreotide