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Radiosynthesis of the candidate β‐amyloid radioligand [ 11 C]AZD2184: Positron emission tomography examination and metabolite analysis in cynomolgus monkeys
Author(s) -
Andersson Jan D.,
Varnäs Katarina,
Cselényi Zsolt,
Gulyás Balázs,
Wensbo David,
Finnema Sjoerd J.,
Swahn BrittMarie,
Svensson Samuel,
Nyberg Svante,
Farde Lars,
Halldin Christer
Publication year - 2010
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/syn.20782
Subject(s) - radioligand , radiosynthesis , positron emission tomography , pittsburgh compound b , in vivo , chemistry , nuclear medicine , metabolite , methyl iodide , ex vivo , radiochemistry , brain positron emission tomography , positron , preclinical imaging , pathology , alzheimer's disease , medicine , in vitro , biochemistry , biology , physics , microbiology and biotechnology , disease , medicinal chemistry , quantum mechanics , electron
β‐Amyloid accumulation is associated with the pathogenesis of Alzheimer's disease (AD). AZD2184, a new radioligand for high‐contrast positron emission tomography (PET) imaging of Aβ‐deposits, has recently been developed and characterized in vitro and in rodents ex vivo. The objective of this study was to label AZD2184 with carbon‐11, to perform in vivo characterization of [ 11 C]AZD2184 ([ 11 C] 5 ) in the cynomolgus monkey brain as well as whole‐body dosimetry, and to examine the metabolism of the labeled radioligand. [ 11 C] 5 was prepared by a two‐step radiosynthesis starting with the reaction of 5‐(6‐( tert ‐butyldimethylsilyloxy)benzo[d]thiazol‐2‐yl)pyridin‐2‐amine with [ 11 C]methyl iodide followed by deprotection using water. Four brain PET measurements in two cynomolgus monkeys and one whole‐body PET measurement were performed with [ 11 C] 5 . There was a high and rapid brain uptake (2.2–3.4% of injected dose at 2 min). The distribution of brain radioactivity was fairly uniform, with early to late‐brain concentration ratios (peak vs. 60 min) higher for [ 11 C] 5 than ratios previously reported for [ 11 C]PIB (8.2 and 4.6, respectively). Based on the whole‐body data, it was estimated that an effective dose in an adult male would be 6.2 μSv/MBq and thus would be safe from a radiation point of view for multiple scans within the same year. [ 11 C] 5 shows binding characteristics, suggesting low levels of white‐matter retention, and may thus provide improved contrast when compared with currently used PET radioligands for visualization of Aβ‐deposits. On the basis of the labeling chemistry and the results of the biological evaluation, we conclude that [ 11 C] 5 should be useful for routine clinical studies. Synapse 64:733–741, 2010. © 2010 Wiley‐Liss, Inc.