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@ARTICLE{Schneider:868015,
author = {Schneider, Daniela and Oskamp, Angela and Holschbach,
Marcus and Neumaier, Bernd and Bier, Dirk and Bauer,
Andreas},
title = {{I}nfluence of binding affinity and blood plasma level on
cerebral pharmacokinetics and {PET} imaging characteristics
of two novel xanthine {PET} radioligands for the {A}1
adenosine receptor},
journal = {Nuclear medicine and biology},
volume = {82-83},
issn = {0969-8051},
address = {Amsterdam [u.a.]},
publisher = {Elsevier Science},
reportid = {FZJ-2019-06608},
pages = {1 - 8},
year = {2020},
abstract = {The suitability of novel positron emission tomography (PET)
radioligands for quantitative in vivo imaging is affected by
various physicochemical and pharmacological parameters. In
this study, the combined effect of binding affinity,
lipophilicity, protein binding and blood plasma level on
cerebral pharmacokinetics and PET imaging characteristics of
three xanthine-derived A1 adenosine receptor (A1AR)
radioligands was investigated in rats.A comparative
evaluation of two novel cyclobutyl-substituted xanthine
derivatives,
8-cyclobutyl-3-(3-[18F]fluoropropyl)-1-propylxanthine
([18F]CBX) and
3-(3-[18F]fluoropropyl)-8-(1-methylcyclobutyl)-1-propylxanthine
([18F]MCBX), with the reference A1AR radioligand
8-cyclopentyl-3-(3-[18F]fluoropropyl)-1-propylxanthine
([18F]CPFPX) was conducted. This evaluation included in
vitro competition binding assays, in vitro autoradiography
and in vivo PET imaging. Differences in cerebral
pharmacokinetics and minimal scan duration required for
quantification of cerebral distribution volume (VT) were
assessed.Measured Ki values of non-labeled CBX, MCBX and
CPFPX were 10.0 ± 0.52 nM, 3.3 ± 0.30 nM and 1.4 ± 0.15
nM, respectively (n = 3–4). In vitro autoradiographic
binding patterns in rat brain were comparable between the
radioligands, as well as the fraction of non-specific
binding $(1.0–1.9\%).$ In vivo cerebral pharmacokinetics
of the novel cyclobutyl-substituted xanthines differed
considerably from that of [18F]CPFPX. Brain uptake and VT of
[18F]CBX were substantially lower despite the higher
concentration of radiotracer in plasma. [18F]MCBX showed
comparable uptake and VT, but faster cerebral kinetics than
[18F]CPFPX. However, the faster kinetics of [18F]MCBX did
not enable the quantification of cerebral VT in a shorter
scan time.The combined effect of individual physicochemical
and pharmacological properties of a radiotracer on its PET
imaging characteristics cannot be readily predicted. In vivo
performance of the xanthine A1AR radioligands was mainly
influenced by binding affinity; plasma concentrations and
cerebral kinetics were of secondary importance.},
cin = {INM-5 / INM-2},
ddc = {570},
cid = {I:(DE-Juel1)INM-5-20090406 / I:(DE-Juel1)INM-2-20090406},
pnm = {573 - Neuroimaging (POF3-573)},
pid = {G:(DE-HGF)POF3-573},
typ = {PUB:(DE-HGF)16},
pubmed = {pmid:31838339},
UT = {WOS:000528670200001},
doi = {10.1016/j.nucmedbio.2019.12.001},
url = {https://juser.fz-juelich.de/record/868015},
}