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Quantitative pharmacological analysis of antagonist binding kinetics at CRF 1 receptors in vitro and in vivo
Author(s) -
Ramsey Simeon J,
Attkins Neil J,
Fish Rebecca,
van der Graaf Piet H
Publication year - 2011
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.2011.01390.x
Subject(s) - in vivo , receptor , receptor–ligand kinetics , in vitro , kinetics , chemistry , antagonist , pharmacology , biophysics , biochemistry , biology , physics , microbiology and biotechnology , quantum mechanics
BACKGROUND AND PURPOSE A series of novel non‐peptide corticotropin releasing factor type‐1 receptor (CRF 1 ) antagonists were found to display varying degrees of insurmountable and non‐competitive behaviour in functional in vitro assays. We describe how we attempted to relate this behaviour to ligand receptor‐binding kinetics in a quantitative manner and how this resulted in the development and implementation of an efficient pharmacological screening method based on principles described by Motulsky and Mahan. EXPERIMENTAL APPROACH A non‐equilibrium binding kinetic assay was developed to determine the receptor binding kinetics of non‐peptide CRF 1 antagonists. Nonlinear, mixed‐effects modelling was used to obtain estimates of the compounds association and dissociation rates. We present an integrated pharmacokinetic–pharmacodynamic (PKPD) approach, whereby the time course of in vivo CRF 1 receptor binding of novel compounds can be predicted on the basis of in vitro assays. KEY RESULTS The non‐competitive antagonist behaviour appeared to be correlated to the CRF 1 receptor off‐rate kinetics. The integrated PKPD model suggested that, at least in a qualitative manner, the in vitro assay can be used to triage and select compounds for further in vivo investigations. CONCLUSIONS AND IMPLICATIONS This study provides evidence for a link between ligand offset kinetics and insurmountable/non‐competitive antagonism at the CRF 1 receptor. The exact molecular pharmacological nature of this association remains to be determined. In addition, we have developed a quantitative framework to study and integrate in vitro and in vivo receptor binding kinetic behaviour of CRF 1 receptor antagonists in an efficient manner in a drug discovery setting.