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@ARTICLE{Schneider:862365,
author = {Schneider, Daniela and Oskamp, Angela and Holschbach,
Marcus and Neumaier, Bernd and Bauer, Andreas and Bier,
Dirk},
title = {{R}elevance of {I}n {V}itro {M}etabolism {M}odels to {PET}
{R}adiotracer {D}evelopment: {P}rediction of {I}n {V}ivo
{C}learance in {R}ats from {M}icrosomal {S}tability {D}ata},
journal = {Pharmaceuticals},
volume = {12},
number = {2},
issn = {1424-8247},
address = {Basel},
publisher = {MDPI},
reportid = {FZJ-2019-02699},
pages = {57},
year = {2019},
abstract = {The prediction of in vivo clearance from in vitro
metabolism models such as liver microsomes is an established
procedure in drug discovery. The potentials and limitations
of this approach have been extensively evaluated in the
pharmaceutical sector; however, this is not the case for the
field of positron emission tomography (PET) radiotracer
development. The application of PET radiotracers and
classical drugs differs greatly with regard to the amount of
substance administered. In typical PET imaging sessions,
subnanomolar quantities of the radiotracer are injected,
resulting in body concentrations that cannot be readily
simulated in analytical assays. This raises concerns
regarding the predictability of radiotracer clearance from
in vitro data. We assessed the accuracy of clearance
prediction for three prototypical PET radiotracers developed
for imaging the A1 adenosine receptor (A1AR). Using the
half-life (t1/2) approach and physiologically based scaling,
in vivo clearance in the rat model was predicted from
microsomal stability data. Actual clearance could be
accurately predicted with an average fold error (AFE) of
0.78 and a root mean square error (RMSE) of 1.6. The
observed slight underprediction (1.3-fold) is in accordance
with the prediction accuracy reported for classical drugs.
This result indicates that the prediction of radiotracer
clearance is possible despite concentration differences of
more than three orders of magnitude between in vitro and in
vivo conditions. Consequently, in vitro metabolism models
represent a valuable tool for PET radiotracer development.},
cin = {INM-2 / INM-5},
ddc = {610},
cid = {I:(DE-Juel1)INM-2-20090406 / I:(DE-Juel1)INM-5-20090406},
pnm = {573 - Neuroimaging (POF3-573)},
pid = {G:(DE-HGF)POF3-573},
typ = {PUB:(DE-HGF)16},
pubmed = {pmid:31013984},
UT = {WOS:000477028700012},
doi = {10.3390/ph12020057},
url = {https://juser.fz-juelich.de/record/862365},
}