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Gobbi L, Mercier J, Bang-Andersen B, Nicolas JM, Reilly J, Wagner B, Whitehead D, Briard E, Maguire RP, Borroni E, Auberson YP. A Comparative Study of in vitro Assays for Predicting the Nonspecific Binding of PET Imaging Agents in vivo. ChemMedChem 2019; 15:585-592. [PMID: 31797561 DOI: 10.1002/cmdc.201900608] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 11/27/2019] [Indexed: 01/23/2023]
Abstract
Nonspecific binding (NSB) is a key parameter in optimizing PET imaging tracers. We compared the ability to predict NSB of three available methods: LIMBA, rat fu,brain , and CHI(IAM). Even though NSB is often associated with lipophilicity, we observed that logD does not correlate with any of these assays, clearly indicating that lipophilicity, while influencing NSB, is insufficient to predict it. A cross-comparison of the methods showed that all three correlate and are useful predictors of NSB. The three assays, however, rank the molecules slightly differently, illustrating the challenge of comparing molecules within a narrow chemical space. We also noted that CHI(IAM) values more effectively predict VNS , a measure of in vivo NSB in the human brain. CHI(IAM) measurements might be a closer model of the actual physicochemical interaction between PET tracer candidates and cell membranes, and seems to be the method of choice for the optimization of in vivo NSB.
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Affiliation(s)
- Luca Gobbi
- Pharma Research and Early Development, Roche Innovation Center Basel F. Hoffmann-La Roche Ltd., 4070, Basel, Switzerland
| | - Joël Mercier
- UCB Early Solutions, UCB Biopharma sprl, 1420, Braine-l'Alleud, Belgium
| | - Benny Bang-Andersen
- Molecular Discovery and Innovation, H. Lundbeck A/S, 9 Ottiliavej, 2500, Valby, Denmark
| | | | - John Reilly
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Fabrikstrasse 2, 4056, Basel, Switzerland
| | - Björn Wagner
- Pharma Research and Early Development, Roche Innovation Center Basel F. Hoffmann-La Roche Ltd., 4070, Basel, Switzerland
| | - David Whitehead
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Fabrikstrasse 2, 4056, Basel, Switzerland
| | - Emmanuelle Briard
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Fabrikstrasse 2, 4056, Basel, Switzerland
| | - R Paul Maguire
- UCB Early Solutions, UCB Biopharma sprl, 1420, Braine-l'Alleud, Belgium
| | - Edilio Borroni
- Pharma Research and Early Development, Roche Innovation Center Basel F. Hoffmann-La Roche Ltd., 4070, Basel, Switzerland
| | - Yves P Auberson
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Fabrikstrasse 2, 4056, Basel, Switzerland
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Elfving B, Bjørnholm B, Knudsen GM. Interference of anaesthetics with radioligand binding in neuroreceptor studies. Eur J Nucl Med Mol Imaging 2003; 30:912-5. [PMID: 12715241 DOI: 10.1007/s00259-003-1171-8] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Evaluations of new emission tomography ligands are usually carried out in animals. In order to keep the animals in a restricted position during the scan session, anaesthesia is almost inevitable. In ex vivo rat studies we investigated the interference of ketamine/xylazine, zoletile mixture, isoflurane and halothane with the serotonin re-uptake site, the serotonin(2A) receptor and the dopamine re-uptake site by use of [(3)H]-(S)-citalopram, [(18)F]altanserin and [(125)I]PE2I, respectively. Ketamine/xylazine decreased the target-to-background ratio (mean +/- SD) of [(3)H]-( S)-citalopram from 1.5+/-0.19 to 0.81+/-0.19 (P<0.05), whereas isoflurane and halothane increased the ratio from 1.5+/-0.19 to 1.9+/-0.24 and 2.1+/-0.13 (P<0.05), respectively. Only with the zoletile mixture did the ratio remain unaltered. None of the tested anaesthetics affected the target-to-background ratio of [(18)F]altanserin. The [(125)I]PE2I target-to-background ratio decreased with both ketamine/xylazine (from 12.4+/-0.81 to 10.1+/-1.4, P<0.05) and isoflurane (from 12.4+/-0.81 to 9.5+/-1.1, P<0.05) treated rats, whereas treatment with zoletile mixture and halothane left the ratio unaltered. It is concluded that prior to performance of neuroreceptor radioligand studies, the possible interaction between radioligands and anaesthetics should be carefully evaluated.
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Affiliation(s)
- Betina Elfving
- Neurobiology Research Unit N9201, University hospital Rigshospitalet, Copenhagen, Denmark.
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