Regulation of CYP2B6 in primary human hepatocytes by prototypical inducers.
Article Details
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Faucette SR, Wang H, Hamilton GA, Jolley SL, Gilbert D, Lindley C, Yan B, Negishi M, LeCluyse EL
Regulation of CYP2B6 in primary human hepatocytes by prototypical inducers.
Drug Metab Dispos. 2004 Mar;32(3):348-58.
- PubMed ID
- 14977870 [ View in PubMed]
- Abstract
The objectives of this study were to evaluate the ability of 14 compounds, which differentially activate human pregnane X receptor (hPXR), to induce CYP2B6 expression and to compare CYP2B6 and CYP3A4 concentration- and time-dependent induction by select inducers. Three primary human hepatocyte preparations were treated daily for 3 days with three concentrations of all compounds. Additional concentration- and/or time-response studies were conducted with clotrimazole, phenytoin, phenobarbital, and rifampin in six preparations. CYP2B6 and CYP3A4 protein and activities were assessed by Western blotting, bupropion hydroxylation, and testosterone 6beta-hydroxylation, respectively. To evaluate hPXR activation by the 14 compounds, reporter gene assays were conducted using Huh7 cells cotransfected with hPXR and a CYP2B6 (NR1)5-LUC reporter plasmid. Clotrimazole, phenobarbital, rifampin, and ritonavir strongly induced CYP2B6 and activated hPXR; dexamethasone t-butylacetate and sulfinpyrazone induced CYP2B6 weakly and activated hPXR moderately; paclitaxel strongly activated hPXR but did not increase CYP2B6 expression; carbamazepine and phenytoin moderately or strongly increased CYP2B6 expression but weakly activated hPXR; and dexamethasone, methotrexate, probenecid, sulfadimidine, and troleandomycin demonstrated weak or negligible effects on CYP2B6 and hPXR. EC50 values for CYP2B6 and CYP3A4 induction by clotrimazole, phenobarbital, phenytoin, and rifampin were strongly correlated (r2 = 0.99) and were statistically indistinguishable for clotrimazole, phenytoin, and rifampin. Kinetic constants governing time-dependent induction by phenobarbital and rifampin were also similar between CYP2B6 and CYP3A4. These results indicate that CYP2B6 is highly inducible by known CYP3A4 inducers and suggest that hPXR is a major determinant of CYP2B6-inducible expression for many, but not all, compounds evaluated in this study.
DrugBank Data that Cites this Article
- Drug Targets
Drug Target Kind Organism Pharmacological Action Actions Carbamazepine Nuclear receptor subfamily 1 group I member 2 Protein Humans UnknownActivatorDetails Clotrimazole Nuclear receptor subfamily 1 group I member 2 Protein Humans UnknownActivatorDetails Phenobarbital Nuclear receptor subfamily 1 group I member 2 Protein Humans UnknownActivatorDetails Phenytoin Nuclear receptor subfamily 1 group I member 2 Protein Humans UnknownNot Available Details Ritonavir Nuclear receptor subfamily 1 group I member 2 Protein Humans UnknownActivatorDetails Sulfinpyrazone Nuclear receptor subfamily 1 group I member 2 Protein Humans UnknownActivatorDetails - Drug Enzymes
Drug Enzyme Kind Organism Pharmacological Action Actions Clotrimazole Cytochrome P450 2B6 Protein Humans UnknownInhibitorInducerDetails Fosphenytoin Cytochrome P450 2B6 Protein Humans UnknownInducerDetails Phenobarbital Cytochrome P450 2B6 Protein Humans UnknownInducerDetails Sulfinpyrazone Cytochrome P450 2B6 Protein Humans UnknownInducerDetails