Lidocaine metabolism in human liver microsomes by cytochrome P450IIIA4

Bargetzi, Mario; Aoyama, Toshifumi; Gonzalez, Frank J.; Meyer, Urs

doi:10.1038/clpt.1989.180

Cited by 243 publications

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“…Several human liver P450 from the subfamilies involved in xenobiotic oxidation have already been expressed in different systems, including recombinant simian virus 40 in COS cells and references therein; Romkes et al, 1991;Veronese et al, 1991), recombinant vaccinia viruses in human hepatoma Hep G2 cells (Aoyama et al, 1990a and1990b, and references therein) and recombinant plasmids in the yeast Succharomyces cerevisiae (Yasumori et al, 1989;Brian et al, 1989;Brian et al, 1990;Renaud et al, 1990;Eugster et al, 1990;Ching et al, 1991; Truan, G., Cullin, C., Reisdorf, P., Urban, P. and Pompon, D., unpublished results). P450 NF25 (CYP3A4) is important in pharmacology and toxicology, not only because it is probably the major form of human liver (Guengerich and Turvy, 1991) but also because it is involved in the metabolism of numerous widely used drugs such as nifedipine (Guengerich et al, 1986a), erythromycin and troleandomycin (Renaud et al, 1990 and references therein), quinidine (Guengerich et al, 1986b), cyclosporin A (Kronbach et al, 1988;Aoyama et al, 1989;Combalbert et al, 1989), 1 7a-ethynylestradiol (Guengerich, 1988), midazolam (Kronbach et al, 1989), lidocaine (Bargetzi et al, 1989;Imaoka et al, 1990), and diltiazem (Pichard et al, 1990). P450 NF25 was recently functionally expressed in S. cerevisiue (Renaud et al, 1990;Brian et al, 1990).…”

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confidence: 99%

Optimization of yeast‐expressed human liver cytochrome P450 3A4 catalytic activities by coexpressing NADPH‐cytochrome P450 reductase and cytochrome b₅

Peyronneau

Renaud

Truan

et al. 1992

European Journal of Biochemistry

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Human liver P450 NF25 (CYP3A4) had been previously expressed in Succhuromyces cerevisiue using the inducible GALIO-CYCl promoter and the phosphoglycerate kinase gene terminator [Renaud, J. p., Cullin, C., Pompon, D., Beaune, P. and Mansuy, D. (1990) Eur. J. Biochem. 194,. The use of an improved expression vector [Urban, P., Cullin, C. and Pompon, D. (1990) Biochimie 72,463 -4721 increased the amounts of P450 NF25 produced/culture medium by a factor of five, yielding up to 10 nmol/l. The availability of recently developed host cells that simultaneously overexpress yeast NADPH-P450 reductase and/or express human liver cytochrome b5, obtained through stable integration of the corresponding coding sequences into the yeast genome, led to biotechnological systems with much higher activities of yeast-expressed P450 NF25 and with much better ability to form P450 NF25 -iron-metabolite complexes. %fold, g-fold, and 30-fold rate increases were found respectively for nifedipine 1,4-oxidation, lidocaine N-deethylation and testosterone 6@-hydroxylation between P450 NF25-containing yeast microsomes from the basic strain and from the strain that both overexpresses yeast NADPH-P450 reductase and expresses human cytochrome b5. Even higher turnovers (15-fold, 20-fold and 50-fold rate increases) were obtained using P450 NF25-containing microsomes from the yeast just overexpressing yeast NADPH-P450 reductase in the presence of externally added, purified rabbit liver cytochrome b5. This is explained by the fact that the latter strain contained the highest level of NADPH-P450 reductase activity. It is noteworthy that for the three tested substrates, the presence of human or rabbit cytochrome b, always showed a stimulating effect on the catalytic activities and this effect was saturable. Indeed, addition of rabbit cytochrome b5 to microsomes from a strain expressing human cytochrome b5 did not further enhance the catalytic rates. The yeast expression system was also used to study the formation of a P450-NF25 -iron-metabolite complex. A P450 Fe(I1)-(RNO) complex was obtained upon oxidation of Nhydroxyamphetamine, catalyzed by P450-NF25-containing yeast microsomes. In microsomes from the basic strain expressing P450 NF25, 10% of the starting P450 NF25 was transformed into this metabolite complex, whereas more than 80% of the starting P450 NF25 led to complex formation in microsomes from the strain overexpressing yeast NADPH-P450 reductase. These results show that specific activities of yeast-expressed P450 NF25 may be artificially low, owing to limiting amounts of the associated microsomal redox proteins and emphasize the importance of controlling the amounts of the different components of the monooxygenase complex in order to optimize these catalytic activities, especially when the expression system is to be used for demonstrating metabolic capacities towards new substrates.

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confidence: 99%

Optimization of yeast‐expressed human liver cytochrome P450 3A4 catalytic activities by coexpressing NADPH‐cytochrome P450 reductase and cytochrome b₅

Peyronneau

Renaud

Truan

et al. 1992

European Journal of Biochemistry

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“…Bargetzi et al (1989) have suggested that CYP3A4 contributes in a major way to the biotransformation of lidocaine to MEGX in humans. In this study, an antiserum directed against human CYP3A4 dose-dependently inhibited MEGX formation in human liver microsomes.…”

Section: Discussionmentioning

confidence: 99%

“…However, it is not clear what substrate concentration was used in this study. On the basis of the above in vitro studies (Bargetzi et al 1989;Imaoka et al 1990), it has been suggested that CYP3A4 is the major enzyme mediating lidocaine biotransformation in humans (Dollery 1999).…”

Section: Discussionmentioning

confidence: 99%

“…The primary metabolite of lidocaine is monoethylglycinexylidide (MEGX). Previous in vitro studies with human liver microsomes have suggested that the oxidative N-deethylation of lidocaine to MEGX is catalysed mainly by CYP3A4 (Bargetzi et al 1989;Imaoka et al 1990). Accordingly, CYP3A4 is generally assumed to be the major CYP isoform involved in the metabolism of lidocaine in humans (Dollery 1999).…”

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1999

Pharmacology & Toxicology

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CYP3A4 is generally believed to be the major CYP enzyme involved in the biotransformation of lidocaine in man; however, recent in vivo studies suggest that this may not be the case. We have examined the effects of the CYP3A4 inhibitors erythromycin and ketoconazole and the CYPlA2 inhibitor fluvoxamine on the N-deethylation, i.e. formation of monoethylglycinexylidide (MEGX), and 3-hydroxylation of lidocaine by human liver microsomes. The experiments were carried out at lidocaine concentrations of 5 pM (clinically relevant concentration) and 800 pM. The formation of both MEGX and 3-hydroxylidocaine was best described by a two-enzyme model. At 5 pM of lidocaine, fluvoxamine was a potent inhibitor of the formation of MEGX (ICso 1.2 pM). Ketoconazole and erythromycin also showed an inhibitory effect on MEGX formation, but ketoconazole (IC50 8.5 pM) was a much more potent inhibitor than erythromycin (ICso 200 pM). At 800 pM of lidocaine, fluvoxamine (ICs0 20.7 pM) and ketoconazole (IC50 20.4 pM) displayed a modest inhibitory effect on MEGX formation, whereas erythromycin was a weak inhibitor (ICS0 >250 pM). The 3-hydroxylation of lidocaine was potently inhibited by fluvoxamine at both lidocaine concentrations (ICso 0.16 pM at 5 pM and 1.8 pM at 800 pM). Erythromycin and ketoconazole showed a clear inhibitory effect on the 3-hydroxylation of lidocaine at 5 pM of lidocaine (ICso 9.9 pM and 13.9 pM, respectively), but did not show a consistent effect at 800 pM of lidocaine (IC50 ,250 pM and 75.0 pM, respectively). Although further studies are needed to elucidate the role of distinct CYP enzymes in the biotransformation of lidocaine in humans, the findings of this study suggest that while both CYPIA2 and CYP3A4 are involved in the metabolism of lidocaine by human liver microsomes, CYPlA2 is the more important isoform at clinically relevant lidocaine concentrations.

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“…Studies have mg lidocaine irrespective of body weight. In study II, we studied all shown that the N-deethylation of lidocaine is catalyzed by our department's patients with histologically proven cirrhosis who the microsomal P-450 isoenzyme, III A4, 1 and that MEG-X were assigned a MEG-X test for clinical reasons. In addition, we formation depends on liver function.…”

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The low-dose monoethylglycinexylidide test: Assessment of liver function with fewer side effects

et al. 1997

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tients with chronic active hepatitis and cirrhosis. [4][5][6][7] Other The hepatic metabolism of lidocaine (1 mg/kg intravestudies have speculated that the test could replace histology nously) to its metabolite monoethylglycinexylidide for the diagnosis of cirrhosis. [8][9][10] However, in addition to the (MEG-X) is the basis of the standard MEG-X test. To retest's diagnostic value, its side effects must be considered. duce the lidocaine-induced side effects, we evaluated the The majority of authors have reported a low preva-MEG-X formation after 0.5 and 1 mg/kg lidocaine intravelence. 3,4,8,10,11 Only one study reported side effects in almost nously in subjects with normal (n Å 5) and severely imall tested individuals. 9 Surprisingly, the symptoms following paired liver function (n Å 7) (study I). From this study, lidocaine injection were not related to the degree of hepatic a low-dose test (MEG-X concentration 30 minutes after histological changes or to the Child class. 9 Because of these 50 mg lidocaine intravenously [MEG-X 30min ] normalized contradictory findings, the safety of the MEG-X test has been to standard MEG-X test results) was developed. Sensory questioned, and further studies were recommended. 12,13 Most side effects from this low dose and from the standard lidocaine-induced side effects are dose-dependent. In con-MEG-X test were compared in a double-blind, randomtrast, lidocaine clearance and the MEG-X formation rate are ized, cross-over study (study II) comprising 15 individudose-independent. 14 To date, it has not been evaluated als with normal liver function and 45 patients with cirwhether this first-order kinetic model holds true for patients rhosis (15 Child A, 15 Child B, and 15 Child C). In study I, with advanced cirrhosis. If this were the case, it should be MEG-X formation rate was dose-independent in patients possible to reduce side effects by extrapolating MEG-X values with severely impaired liver function. In study II, norobtained with lower lidocaine doses to standard MEG-X test malized MEG-X test results (ranging from°4 to 120 mg/ results. Therefore, we studied (study I) the dose-dependent L) were virtually identical to the standard test results pharmacokinetics of lidocaine in patients with severely im-(mean difference: 01.9 mg/L; 95% confidence interval paired liver function. In a second double-blind randomized [CI]: 05.3; 1.5 mg/L). Fewer individuals experienced side controlled study (study II), we assessed the sensory quality effects (30% vs. 53%) with the low-dose test (P Å .0013).and intensity of patients' side effects with the aim of finding In a multivariate analysis, the Child-Pugh score was intheir relationship to lidocaine dosage and liver function. and 0.5 mg/kg body weight to individuals with normal (n Å 5) and severely impaired liver function (n Å 7). To compare the low-dose versus the standard MEG-X test (study II: double-blind, randomized, Lidocaine is metabolized to its principal metabolite, monocross-over design), we injected 1 mg/kg body weight lidocaine and 50 ...

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Lidocaine metabolism in human liver microsomes by cytochrome P450IIIA4

Cited by 243 publications

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Optimization of yeast‐expressed human liver cytochrome P450 3A4 catalytic activities by coexpressing NADPH‐cytochrome P450 reductase and cytochrome b₅

Optimization of yeast‐expressed human liver cytochrome P450 3A4 catalytic activities by coexpressing NADPH‐cytochrome P450 reductase and cytochrome b₅

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The low-dose monoethylglycinexylidide test: Assessment of liver function with fewer side effects

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Lidocaine metabolism in human liver microsomes by cytochrome P450IIIA4

Cited by 243 publications

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Optimization of yeast‐expressed human liver cytochrome P450 3A4 catalytic activities by coexpressing NADPH‐cytochrome P450 reductase and cytochrome b5

Optimization of yeast‐expressed human liver cytochrome P450 3A4 catalytic activities by coexpressing NADPH‐cytochrome P450 reductase and cytochrome b5

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The low-dose monoethylglycinexylidide test: Assessment of liver function with fewer side effects

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Optimization of yeast‐expressed human liver cytochrome P450 3A4 catalytic activities by coexpressing NADPH‐cytochrome P450 reductase and cytochrome b₅

Optimization of yeast‐expressed human liver cytochrome P450 3A4 catalytic activities by coexpressing NADPH‐cytochrome P450 reductase and cytochrome b₅