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Analysis of the metabolites of [I‐123]β‐CIT in plasma of human and nonhuman primates
Author(s) -
Heinz Andreas,
Jones Douglas W.,
Gorey Julia G.,
Knable Michael B.,
Lee Kan Sam,
Saunders Richard C.,
Weinberger Daniel R.
Publication year - 1997
Publication title -
synapse
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.809
H-Index - 106
eISSN - 1098-2396
pISSN - 0887-4476
DOI - 10.1002/(sici)1098-2396(199703)25:3<306::aid-syn10>3.0.co;2-u
Subject(s) - human plasma , nonhuman primate , neuroscience , computational biology , cognitive science , psychology , pharmacology , chemistry , biology , evolutionary biology , chromatography
[I‐123]β‐CIT is a single photon emission computed tomography (SPECT) radioligand that has been used for in vivo studies of the dopamine and serotonin transporters. Two metabolite peaks of β‐CIT have been observed by high performance liquid chromatography (HPLC), but neither has been chemically identified. One major metabolite is clearly hydrophilic. Previous reports have not agreed on the amount of the second metabolite and the extent to which it may cross the blood‐brain barrier. To clarify this controversy, we have studied β‐CIT metabolites using a protein precipitation method and an organic extraction method followed by HPLC separation. Plasma from both human and nonhuman (rhesus) primates was analyzed. Concentrations of the second metabolite were substantially lower in rhesus than in human for nearly equal parent concentrations. Furthermore, in rhesus the second metabolite is partially soluble in the organic solvent ethyl acetate, whereas in human it is essentially insoluble. These observations account for the contradictions in the literature. The hydrophilic nature of the human metabolite renders it unlikely that it crosses the blood‐brain barrier in sufficient quantities to interfere with the quantitative assessment of dopamine transporter densities. Synapse 25:306–308, 1997. © 1997 Wiley‐Liss, Inc. This article is a US government work and, as such, is in the public domain in the United States of America.