Comparison of Enzyme Kinetic Parameters Obtained In Vitro for Reactions Mediated by Human CYP2C Enzymes Including Major CYP2C9 Variants

Abstract

Cytochrome P450 (CYP) 2C enzymes contribute to the metabolism of about 30% of all drugs. Known polymorphisms of the respective enzymes and drug-drug interactions have a major impact on the efficacy and safety of some CYP2C substrate drugs. In vivo - in vitro correlations including prediction of the effect of such covariates requires quantitative information on enzyme kinetics. In this article there will be a summary of the values of the Michaelis-Menten constant (K(m)), the maximal velocity (V(max)) and the intrinsic clearance (Cl(int); V(max)/K(m)) for 84 substrates (100 reactions) reported to be mediated by CYP2C9 (variant enzymes CYP2C9.1, CYP2C9.2 and CYP2C9.3), CYP2C8 and/or CYP2C19. Particularly contradictory findings for the same reactions call for some standardization in the assessment of enzyme kinetics.

High warfarin sensitivity in carriers of CYP2C9*35 is determined by the impaired interaction with P450 oxidoreductase

“…The CYP2C9 variant that contains only this mutation is known as CYP2C9.2 and its expression causes a moderately reduced enzyme activity toward several substrates including warfarin, diclofenac and losartan. 9,11,47 This is in line with our data obtained in the HEK293 cell system showing reduced activity of CYP2C9-R144C toward S-warfarin in NADPH-PORsupported system. However, the structural basis for the reduced catalytic activity of CYP2C9-R144C remains elusive.…”

“…Figure S2A) mediated by CYP2C9.1 and CYP2C9-R144C followed the Michaelis-Menten kinetics, which is in line with previously reported data. 9,11,12 However, the rate of both S-warfarin and diclofenac metabolism in the presence of CYP2C9 variants containing the Arg125Leu substitution, that is, CYP2C9-R125L and CYP2C9.35, was at the level of the background activity in the mock-transfected cells (Figure 2 and Supplementary Figures S1A and S2A). Identical results were obtained using yet another CYP2C9 substrate, losartan (results not shown).…”

“…7,8 The CYP2C9*2 and *3 variant alleles cause significantly decreased activity toward many other drugs, such as diclofenac, 9 losartan 10 and others. 11,12 The molecular and structural basis for altered catalytic properties of polymorphic CYP enzyme variants is often poorly studied. However, the recent advances in resolution of three-dimensional structures of many CYPs including CYP2C9 13,14 allowed the development of various computational approaches that are currently applied for quantitative prediction of pharmacokinetics, interaction between the enzyme and its substrates, and also redox partners.…”

Inhibition of human cytochrome P450 enzymes by hops (Humulus lupulus) and hop prenylphenols

“…Enzymes of the 2C subfamily account for approximately 25% of total human liver cytochrome P450 (Ioannides, 1996) and metabolize a large number of drugs. For example, CYP2C8 is responsible for the metabolism of statins that are widely prescribed to combat hypercholesterolemia (Rokitta and Fuhr, 2010), and CYP2C9 is responsible for the metabolism of many clinically important drugs such as the anticoagulant drug warfarin and many nonsteroidal anti-inflammatory drugs (Goldstein and De Morais, 1994). Therefore, inhibition of CYP2C enzymes by hop dietary supplements might be worth further investigation in clinical trials as a potential source of drug-botanical interactions.…”

Cytochrome P450 1B1 and 2C9 Genotypes and Risk of Ischemic Vascular Disease, Cancer, and Chronic Obstructive Pulmonary Disease

“…Compared with CYP2C9*1, CYP2C9*2 and CYP2C9*3 metabolize warfarin and other substrates more slowly [15,16,71]. Computational analysis of the interaction between the enzyme and substrate has further established that the binding pocket is deformed in CYP2C9*2 and CYP2C9*3 for a number of substrates, explaining the decreased activity [72].…”