title: Evaluation of fluorescence- and mass spectrometry-based CYP inhibition assays for use in drug discovery.
abstract: The potential for metabolism-related drug-drug interactions by new chemical entities is assessed by monitoring the impact of these compounds on cytochrome P450 (CYP) activity using well-characterized CYP substrates. The conventional gold standard approach for in vitro evaluation of CYP inhibitory potential uses pooled human liver microsomes (HLM) in conjunction with prototypical drug substrates, often quantified by LC-MS/MS. However, fluorescent CYP inhibition assays, which use recombinantly expressed CYPs and fluorogenic probe substrates, have been employed in early drug discovery to provide low-cost, high-throughput assessment of new chemical entities. Despite its greatly enhanced throughput, this approach has been met with mixed success in predicting the data obtained with the conventional gold standard approach (HLM+LC-MS). The authors find that the predictivity of fluorogenic assays for the major CYP isoforms 3A4 and 2D6 may depend on the quality of the test compounds. Although the structurally more optimized marketed drugs yielded acceptable correlations between the fluorogenic and HLM+LC-MS/MS assays for CYPs 3A4, 2D6, and 2C9 (r2 = 0.5-0.7; p < 0.005), preoptimization, early discovery compounds yielded poorer correlations (r2 < or = 0.2) for 2 of these major isoforms, CYPs 3A4 and 2D6. Potential reasons for the observed differences are discussed.
authors.affiliation: ADME Profiling Cambridge, Metabolism and Pharmacokinetics, Global Discovery Chemistry, Novartis Institutes for Biomedical Research, Cambridge, Massachusetts 02139, USA. leslie.bell@novartis.com
authors.forename: Leslie
authors.initials: L
authors.lastname: Bell
authors.forename: Shari
authors.initials: S
authors.lastname: Bickford
authors.forename: Phong Hung
authors.initials: PH
authors.lastname: Nguyen
authors.forename: Jianling
authors.initials: J
authors.lastname: Wang
authors.forename: Timothy
authors.initials: T
authors.lastname: He
authors.forename: Bailin
authors.initials: B
authors.lastname: Zhang
authors.forename: Yannick
authors.initials: Y
authors.lastname: Friche
authors.forename: Alfred
authors.initials: A
authors.lastname: Zimmerlin
authors.forename: Laszlo
authors.initials: L
authors.lastname: Urban
authors.forename: Dejan
authors.initials: D
authors.lastname: Bojanic
mesh_terms: D065607:Cytochrome P-450 Enzyme Inhibitors; D015195:Drug Design; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000494:pharmacology; D013050:Spectrometry, Fluorescence / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D065607:Cytochrome P-450 Enzyme Inhibitors; D004791:Enzyme Inhibitors