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Simulating the influence of plasma protein on measured receptor affinity in biochemical assays reveals the utility of Schild analysis for estimating compound affinity for plasma proteins

Blakeley, D; Sykes, D A; Ensor, P; Bertran, E; Aston, P J; Charlton, Steven J.

Simulating the influence of plasma protein on measured receptor affinity in biochemical assays reveals the utility of Schild analysis for estimating compound affinity for plasma proteins Thumbnail


Authors

D Blakeley

D A Sykes

P Ensor

E Bertran

P J Aston

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STEVEN CHARLTON Steven.Charlton@nottingham.ac.uk
Professor of Molecular Pharmacology and Drug Discovery



Abstract

© 2015 The British Pharmacological Society. Background and Purpose Plasma protein binding (PPB) influences the free fraction of drug available to bind to its target and is therefore an important consideration in drug discovery. While traditional methods for assessing PPB (e.g. rapid equilibrium dialysis) are suitable for comparing compounds with relatively weak PPB, they are not able to accurately discriminate between highly bound compounds (typically >99.5%). The aim of the present work was to use mathematical modelling to explore the potential utility of receptor binding and cellular functional assays to estimate the affinity of compounds for plasma proteins. Plasma proteins are routinely added to in vitro assays, so a secondary goal was to investigate the effect of plasma proteins on observed ligand-receptor interactions. Experimental Approach Using the principle of conservation of mass and the law of mass action, a cubic equation was derived describing the ligand-receptor complex [LR] in the presence of plasma protein at equilibrium. Key Results The model demonstrates the profound influence of PPB on in vitro assays and identifies the utility of Schild analysis, which is usually applied to determine receptor-antagonist affinities, for calculating affinity at plasma proteins (termed KP). We have also extended this analysis to functional effects using operational modelling and demonstrate that these approaches can also be applied to cell-based assay systems. Conclusions and Implications These mathematical models can potentially be used in conjunction with experimental data to estimate drug-plasma protein affinities in the earliest phases of drug discovery programmes.

Citation

Charlton, S. J., Blakeley, D., Sykes, D. A., Ensor, P., Bertran, E., Aston, P. J., & Charlton, S. J. (2015). Simulating the influence of plasma protein on measured receptor affinity in biochemical assays reveals the utility of Schild analysis for estimating compound affinity for plasma proteins. British Journal of Pharmacology, 172(21), 5037-5049. https://doi.org/10.1111/bph.13263

Journal Article Type Article
Acceptance Date Jul 17, 2015
Online Publication Date Oct 22, 2015
Publication Date 2015-11
Deposit Date Dec 13, 2019
Publicly Available Date Mar 28, 2024
Journal British Journal of Pharmacology
Print ISSN 0007-1188
Electronic ISSN 1476-5381
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 172
Issue 21
Pages 5037-5049
DOI https://doi.org/10.1111/bph.13263
Public URL https://nottingham-repository.worktribe.com/output/3180420
Publisher URL https://bpspubs.onlinelibrary.wiley.com/doi/full/10.1111/bph.13263