Abstract
Introduction: A novel [{sup 18}F]-radiolabelled phenoxyanilide, [{sup 18}F]-FEPPA, has been synthesized and evaluated, in vitro and ex vivo, as a potential positron emission tomography imaging agent for the peripheral benzodiazepine receptor (PBR). Methods: [{sup 18}F]-FEPPA and two other radiotracers for imaging PBR, namely [{sup 11}C]-PBR28 and [{sup 11}C]-PBR28-d3, were synthesised and evaluated in vitro and ex vivo as potential PBR imaging agents. Results: [{sup 18}F]-FEPPA is efficiently prepared in one step from its tosylate precursor and [{sup 18}F]-fluoride in high radiochemical yields and at high specific activity. FEPPA displayed a K{sub i} of 0.07 nM for PBR in rat mitochondrial membrane preparations and a suitable lipophilicity for brain penetration (log P of 2.99 at pH 7.4). Upon intravenous injection into rats, [{sup 18}F]-FEPPA showed moderate brain uptake [standard uptake value (SUV) of 0.6 at 5 min] and a slow washout (SUV of 0.35 after 60 min). Highest uptake of radioactivity was seen in the hypothalamus and olfactory bulb, regions previously reported to be enriched in PBR in rat brain. Analysis of plasma and brain extracts demonstrated that [{sup 18}F]-FEPPA was rapidly metabolized, but no lipophilic metabolites were observed in either preparation and only 5% radioactive metabolites were present in brain
More>>
Wilson, Alan A;
[1]
Department of Psychiatry, University of Toronto, Toronto, Ontario, M5T 1R8 (Canada)], E-mail: alan.wilson@camhpet.ca;
Garcia, Armando;
Parkes, Jun;
[1]
McCormick, Patrick;
[1]
Institute of Medical Science, University of Toronto, Toronto, Ontario, M5S 1A8 (Canada)];
Stephenson, Karin A;
[1]
Houle, Sylvain;
Vasdev, Neil;
[1]
Department of Psychiatry, University of Toronto, Toronto, Ontario, M5T 1R8 (Canada)]
- PET Centre, Centre for Addiction and Mental Health, Toronto, Ontario, M5T 1R8 (Canada)
Citation Formats
Wilson, Alan A, Department of Psychiatry, University of Toronto, Toronto, Ontario, M5T 1R8 (Canada)], E-mail: alan.wilson@camhpet.ca, Garcia, Armando, Parkes, Jun, McCormick, Patrick, Institute of Medical Science, University of Toronto, Toronto, Ontario, M5S 1A8 (Canada)], Stephenson, Karin A, Houle, Sylvain, Vasdev, Neil, and Department of Psychiatry, University of Toronto, Toronto, Ontario, M5T 1R8 (Canada)].
Radiosynthesis and initial evaluation of [{sup 18}F]-FEPPA for PET imaging of peripheral benzodiazepine receptors.
United Kingdom: N. p.,
2008.
Web.
doi:10.1016/j.nucmedbio.2007.12.009.
Wilson, Alan A, Department of Psychiatry, University of Toronto, Toronto, Ontario, M5T 1R8 (Canada)], E-mail: alan.wilson@camhpet.ca, Garcia, Armando, Parkes, Jun, McCormick, Patrick, Institute of Medical Science, University of Toronto, Toronto, Ontario, M5S 1A8 (Canada)], Stephenson, Karin A, Houle, Sylvain, Vasdev, Neil, & Department of Psychiatry, University of Toronto, Toronto, Ontario, M5T 1R8 (Canada)].
Radiosynthesis and initial evaluation of [{sup 18}F]-FEPPA for PET imaging of peripheral benzodiazepine receptors.
United Kingdom.
https://doi.org/10.1016/j.nucmedbio.2007.12.009
Wilson, Alan A, Department of Psychiatry, University of Toronto, Toronto, Ontario, M5T 1R8 (Canada)], E-mail: alan.wilson@camhpet.ca, Garcia, Armando, Parkes, Jun, McCormick, Patrick, Institute of Medical Science, University of Toronto, Toronto, Ontario, M5S 1A8 (Canada)], Stephenson, Karin A, Houle, Sylvain, Vasdev, Neil, and Department of Psychiatry, University of Toronto, Toronto, Ontario, M5T 1R8 (Canada)].
2008.
"Radiosynthesis and initial evaluation of [{sup 18}F]-FEPPA for PET imaging of peripheral benzodiazepine receptors."
United Kingdom.
https://doi.org/10.1016/j.nucmedbio.2007.12.009.
@misc{etde_21119201,
title = {Radiosynthesis and initial evaluation of [{sup 18}F]-FEPPA for PET imaging of peripheral benzodiazepine receptors}
author = {Wilson, Alan A, Department of Psychiatry, University of Toronto, Toronto, Ontario, M5T 1R8 (Canada)], E-mail: alan.wilson@camhpet.ca, Garcia, Armando, Parkes, Jun, McCormick, Patrick, Institute of Medical Science, University of Toronto, Toronto, Ontario, M5S 1A8 (Canada)], Stephenson, Karin A, Houle, Sylvain, Vasdev, Neil, and Department of Psychiatry, University of Toronto, Toronto, Ontario, M5T 1R8 (Canada)]}
abstractNote = {Introduction: A novel [{sup 18}F]-radiolabelled phenoxyanilide, [{sup 18}F]-FEPPA, has been synthesized and evaluated, in vitro and ex vivo, as a potential positron emission tomography imaging agent for the peripheral benzodiazepine receptor (PBR). Methods: [{sup 18}F]-FEPPA and two other radiotracers for imaging PBR, namely [{sup 11}C]-PBR28 and [{sup 11}C]-PBR28-d3, were synthesised and evaluated in vitro and ex vivo as potential PBR imaging agents. Results: [{sup 18}F]-FEPPA is efficiently prepared in one step from its tosylate precursor and [{sup 18}F]-fluoride in high radiochemical yields and at high specific activity. FEPPA displayed a K{sub i} of 0.07 nM for PBR in rat mitochondrial membrane preparations and a suitable lipophilicity for brain penetration (log P of 2.99 at pH 7.4). Upon intravenous injection into rats, [{sup 18}F]-FEPPA showed moderate brain uptake [standard uptake value (SUV) of 0.6 at 5 min] and a slow washout (SUV of 0.35 after 60 min). Highest uptake of radioactivity was seen in the hypothalamus and olfactory bulb, regions previously reported to be enriched in PBR in rat brain. Analysis of plasma and brain extracts demonstrated that [{sup 18}F]-FEPPA was rapidly metabolized, but no lipophilic metabolites were observed in either preparation and only 5% radioactive metabolites were present in brain tissue extracts. Blocking studies to determine the extent of specific binding of [{sup 18}F]-FEPPA in rat brain were problematic due to large perturbations in circulating radiotracer and the lack of a reference region. Conclusions: Further evaluation of the potential of [{sup 18}F]-FEPPA will require the employment of rigorous kinetic models and/or appropriate animal models.}
doi = {10.1016/j.nucmedbio.2007.12.009}
journal = []
issue = {3}
volume = {35}
place = {United Kingdom}
year = {2008}
month = {Apr}
}
title = {Radiosynthesis and initial evaluation of [{sup 18}F]-FEPPA for PET imaging of peripheral benzodiazepine receptors}
author = {Wilson, Alan A, Department of Psychiatry, University of Toronto, Toronto, Ontario, M5T 1R8 (Canada)], E-mail: alan.wilson@camhpet.ca, Garcia, Armando, Parkes, Jun, McCormick, Patrick, Institute of Medical Science, University of Toronto, Toronto, Ontario, M5S 1A8 (Canada)], Stephenson, Karin A, Houle, Sylvain, Vasdev, Neil, and Department of Psychiatry, University of Toronto, Toronto, Ontario, M5T 1R8 (Canada)]}
abstractNote = {Introduction: A novel [{sup 18}F]-radiolabelled phenoxyanilide, [{sup 18}F]-FEPPA, has been synthesized and evaluated, in vitro and ex vivo, as a potential positron emission tomography imaging agent for the peripheral benzodiazepine receptor (PBR). Methods: [{sup 18}F]-FEPPA and two other radiotracers for imaging PBR, namely [{sup 11}C]-PBR28 and [{sup 11}C]-PBR28-d3, were synthesised and evaluated in vitro and ex vivo as potential PBR imaging agents. Results: [{sup 18}F]-FEPPA is efficiently prepared in one step from its tosylate precursor and [{sup 18}F]-fluoride in high radiochemical yields and at high specific activity. FEPPA displayed a K{sub i} of 0.07 nM for PBR in rat mitochondrial membrane preparations and a suitable lipophilicity for brain penetration (log P of 2.99 at pH 7.4). Upon intravenous injection into rats, [{sup 18}F]-FEPPA showed moderate brain uptake [standard uptake value (SUV) of 0.6 at 5 min] and a slow washout (SUV of 0.35 after 60 min). Highest uptake of radioactivity was seen in the hypothalamus and olfactory bulb, regions previously reported to be enriched in PBR in rat brain. Analysis of plasma and brain extracts demonstrated that [{sup 18}F]-FEPPA was rapidly metabolized, but no lipophilic metabolites were observed in either preparation and only 5% radioactive metabolites were present in brain tissue extracts. Blocking studies to determine the extent of specific binding of [{sup 18}F]-FEPPA in rat brain were problematic due to large perturbations in circulating radiotracer and the lack of a reference region. Conclusions: Further evaluation of the potential of [{sup 18}F]-FEPPA will require the employment of rigorous kinetic models and/or appropriate animal models.}
doi = {10.1016/j.nucmedbio.2007.12.009}
journal = []
issue = {3}
volume = {35}
place = {United Kingdom}
year = {2008}
month = {Apr}
}