Preclinical evaluation of drug—drug interaction potential: present status of the application of primary human hepatocytes in the evaluation of cytochrome P450 induction

Li, Albert P.; Maurel, Patrick; Gómez-Lechón, Marı́a José; Cheng, Larry C.; Jurima-Romet, Malle

doi:10.1016/s0009-2797(97)00070-7

Cited by 123 publications

(55 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Assuming that the persistent metabolic effect we estimate is real, one possible mechanism for it is irreversible inactivation of the CYP3A4 enzyme responsible for S metabolism by R, possibly through the formation of metabolic intermediate complexes (Koudriakova et al, 1998). Return of metabolic capacity with such a mechanism would occur at a rate governed by the resynthesis rate of the relevant CYP3A4, rather than by the disappearance rate of plasma R, and this is compatible with our estimated 30-h half-life of persistence (Barry and Feely, 1990;Li et al, 1997). Although R (and N) are known to be (rapidly) reversible competitive inhibitors of CYP3A4 (Kempf et al, 1997;Lillibridge et al, 1998), that does not rule out an irreversible component as well.…”

Section: Ritonavir Nelfinavir and Saquinavir Interactionssupporting

confidence: 87%

Model-based Analysis of the Pharmacokinetic Interactions Between Ritonavir, Nelfinavir, and Saquinavir after Simultaneous and Staggered Oral Administration

Blaschke

Flexner³

et al. 2002

Drug Metab Dispos

View full text Add to dashboard Cite

ABSTRACT:Eighteen healthy human immunodeficiency virus-negative subjects participated in an open-label, six-period, incomplete Latinsquare crossover pharmacokinetic study. Each subject received two of the three possible pair-wise combinations of single-dose oral ritonavir (R) (400 mg), nelfinavir (N) (750 mg), and saquinavir (S) (800 mg), each pair on three occasions (simultaneous or staggered administration), each occasion at least 2 days after the last. A model-based analysis reveals the following major drug interactions under the conditions of this study: 1) R given simultaneously with S decreases S hepatic intrinsic clearance almost 50-fold relative to that predicted for S given alone and increases its gut bioavailability 90% (but decreases its rate of absorption 40%) relative to when N is given simultaneously; 2) N given simultaneously with S decreases S hepatic intrinsic clearance 10-fold relative to that predicted for S given alone; and 3) R inhibits S hepatic intrinsic clearance even after R plasma levels have become undetectable (>48 h after dosing), implying that R, when used as a pharmacokinetic enhancer, can be dosed less frequently than might be predicted from the duration of detectable systemic concentrations.Protease inhibitors (PIs 1 ) ritonavir (R), nelfinavir (N), and saquinavir (S) are primarily metabolized by CYP3A4 (and partially by other cytochromes P450) in the liver (Eagling et al., 1997;Fitzsimmons and Collins, 1997;Hsu et al., 1998a;Kim et al., 1998;Washington et al., 1998). They exhibit extensive pharmacokinetic (PK) interactions (Merry et al., 1997;Hsu et al., 1998b;Jarvis et al., 1998), but the degree to which those interactions occur at the level of hepatic metabolism, gut metabolism, or gut efflux transporters is still uncertain. Adult AIDS clinical trial group study 378 (ACTG 378), involving staggered versus simultaneous administration of the three PIs, was designed to shed light on these issues. The findings with respect to changes of AUC (proportional to the ratio of systemic clearance to bioavailability) are reported elsewhere (C. B. Washington, C. Flexner, L. B. Sheiner, S. L. Rosenkranz, M.A. Jacobson, T. F. Blaschke, submitted); they are considerable. This paper extends those findings by presenting a physiologically based population pharmacokinetic model applied to the full ACTG 378 data to assess and quantify the gut versus hepatic mechanisms responsible for the AUC changes and for any other PK interactions. Materials and MethodsData Source. ACTG 378 was an open-label, Latin-square design study of the effect of staggered versus simultaneous dosing on the PK profiles of the following three protease inhibitors: R, N, and S (we use the symbols R, N, S to refer not only to the drugs but to their concentrations; context should make clear which meaning is intended). A total of 18 human immunodeficiency virus-negative healthy volunteers participated in the study, and each was randomized to receive two of the three pairs (N ϩ R, N ϩ S, and R ϩ S) in two series of three occasions. T...

show abstract

Section: Ritonavir Nelfinavir and Saquinavir Interactionssupporting

confidence: 87%

Model-based Analysis of the Pharmacokinetic Interactions Between Ritonavir, Nelfinavir, and Saquinavir after Simultaneous and Staggered Oral Administration

Blaschke

Flexner³

et al. 2002

Drug Metab Dispos

View full text Add to dashboard Cite

show abstract

“…Compared with transformed cells, human primary hepatocyte cultures have been recognized as a more reliable in vitro model for evaluating the induction of drug-metabolizing enzymes in human liver (30,31). One possible reason for the maintenance of xenobiotic inducibility of drug-metabolizing enzymes in primary but not transformed cells is the retention of In agreement with our previous report, greater increases were observed with transfection of the PBREM/XREM reporter construct compared with the construct containing the PBREM alone (10).…”

Section: Phy Activates and Translocates Hcar In Vivo Insupporting

confidence: 85%

Human Constitutive Androstane Receptor Mediates Induction of CYP2B6 Gene Expression by Phenytoin

Wang

Faucette

Moore

et al. 2004

Journal of Biological Chemistry

139

100

View full text Add to dashboard Cite

Compared with its rodent orthologs, little is known about the chemical specificity of human constitutive androstane receptor (hCAR) and its regulation of hepatic enzyme expression. Phenytoin (PHY), a widely used antiepileptic drug, is a potent inducer of CYP2B6 in primary human hepatocytes, but does not activate human pregnane X receptor (PXR) significantly in cellbased transfection assays at the same concentrations associated with potent induction of CYP2B6. Based on this observation, we hypothesized that PHY may be a selective activator of hCAR. In primary human hepatocytes, expression of CYP2B6 reporter genes containing phenobarbital-responsive enhancer module (PBREM) or PBREM/xenobiotic-responsive enhancer module (XREM) response elements were activated up to 14-and 28-fold, respectively, by 50 M PHY. By contrast, parallel experiments in HepG2 cell lines co-transfected with an hPXR expression vector did not show increased reporter activity. These results indicated that a PXR-independent pathway, which is retained in primary hepatocytes, is responsible for PHY induction of CYP2B6. Further experiments revealed that PHY effectively translocates hCAR from the cytoplasm into the nucleus in both primary human hepatocytes and CAR ؊/؊ mice. Compared with vehicle controls, PHY administration significantly increased CYP2B6 reporter gene expression, when this reporter construct was delivered together with hCAR expression vector into CAR ؊/؊ mice. However, PHY did not increase reporter gene expression in CAR ؊/؊ mice in the absence of hCAR vector, implying that CAR is essential for mediating PHY induction of CYP2B6 gene expression. Taken together, these observations demonstrate that, in contrast to most of the known CYP2B6 inducers, PHY is a selective activator of CAR in humans.Induction of cytochrome P450 2B (CYP2B) 1 expression by xenobiotics, including clinically used drugs, is mediated by activation of the nuclear receptors constitutive androstane receptor (CAR) and/or pregnane X receptor (PXR) through response elements located in the promoter region of CYP2B genes. In contrast to rodent CYP2B genes, mounting evidence suggests that human PXR (hPXR) may be a key receptor in the regulation of human CYP2B6 gene expression (1-3). hPXR ligands, including rifampicin (RIF), phenobarbital (PB), troglitazone, clotrimazole (CLZ), and SR12813 have been reported to induce CYP2B6 gene expression (1, 4 -7). Recently, fourteen commercially available compounds, including weak, moderate, and strong inducers of CYP2B6 and CYP3A4, were used to compare the potency and magnitude of CYP2B6 and CYP3A4 induction and activation of hPXR in primary cultured hepatocytes and hepatoma cell-based reporter gene assays, respectively. Results from these studies indicate that CYP2B6 induction is highly correlated with the activation of hPXR for most compounds (3). Among the efficacious CYP2B6 inducers evaluated, most activate hPXR but not hCAR, such as RIF and CLZ (CLZ was even reported as a hCAR deactivator by Moore et al. (8)), whereas others can a...

show abstract

“…In contrast to transformed cell lines, primary cultures of human hepatocytes represent the most reliable in vitro model for evaluating the xenobiotic-mediated induction of CYP in human liver (29,34,38). One possible explanation for this phenomenon is that primary hepatocytes retain most of the endogenous cellular and nuclear cofactors that are essential for normal liver function.…”

Section: Fig 3 Pxr/rxr and Car/rxr Heterodimers Bind To Cyp2b6-xremmentioning

confidence: 99%

A Novel Distal Enhancer Module Regulated by Pregnane X Receptor/Constitutive Androstane Receptor Is Essential for the Maximal Induction of CYP2B6 Gene Expression

Wang¹,

Faucette²,

Sueyoshi³

et al. 2003

Journal of Biological Chemistry

203

161

View full text Add to dashboard Cite

CYP2B6 plays an important role in the metabolism of a variety of structurally unrelated xenobiotics, including the anticancer drugs cyclophosphamide and ifosfamide. Previous studies have shown that the nuclear receptors constitutive androstane receptor (CAR) and pregnane X receptor (PXR) are involved in the transcriptional regulation of CYP2B genes through the phenobarbital-responsive enhancer module (PBREM). However, for human CYP2B6 the relatively weak response of the PBREM to PXR and CAR activation in transfection assays fails to describe the potent induction observed in primary human hepatocyte cultures. In this report, a novel nuclear receptor response module located ؊8.5 kilobases upstream from the CYP2B6 encoding region is described. Several potential PXR/CAR binding motifs were identified within the distal regulatory cluster. In electrophoretic mobility shift assays, one DR4 motif showed the strongest binding to both PXR and CAR. Transient transfection assays in HepG2 cells demonstrated that the novel distal response cluster could be activated by PXR and CAR. In primary human hepatocytes, both PBREM and the distal responsive element were activated individually by endogenous nuclear receptors upon exposure to prototypical inducers. However, in both HepG2 cells and primary human hepatocytes maximal reporter activation was observed in a construct containing both PBREM and the distal responsive element. In mouse tail-vein injection experiments, a construct containing both the distal responsive element and the proximal PBREM exhibited a strong synergistic expression in phenobarbital-treated mice. These results show that a novel xenobiotic-responsive enhancer module in the distal region of the CYP2B6 promoter (CYP2B6-XREM) together with the PBREM mediates optimal drug-induced expression of CYP2B6. The cytochrome P450 (CYP)1 gene superfamily plays a critical role in the biotransformation of structurally diverse classes of xenobiotics, including drugs, environmental pollutants, and endogenous compounds such as steroid hormones, vitamins, and fatty acids (1). Predominantly expressed in liver, members of the CYP1-3 families exhibit broad substrate specificity and metabolize the majority of administered drugs. Although human CYP2B6 was thought historically to play only a minor role in drug metabolism, more recent estimates suggest that CYP2B6 is involved in the metabolism of nearly 25% of drugs on the market today (2), such as the anticancer drugs cyclophosphamide, ifosfamide (3), and tamoxifen (4), the anti-retrovirals efavirenz and nevirapine (5), the anesthetics ketamine and propofol (6, 7), and the central nervous system active agents mephobarbital, bupropion, and selegiline (9, 10).2 Moreover, recent studies using more selective and specific immunochemical detection methods demonstrate that the average relative abundance of CYP2B6 in human liver ranges from 2 to 10% of the total P450 content compared with an earlier report of 0.2% (11)(12)(13)(14). In addition, significant interindividual differences in hepati...

show abstract

Preclinical evaluation of drug—drug interaction potential: present status of the application of primary human hepatocytes in the evaluation of cytochrome P450 induction

Cited by 123 publications

References 31 publications

Model-based Analysis of the Pharmacokinetic Interactions Between Ritonavir, Nelfinavir, and Saquinavir after Simultaneous and Staggered Oral Administration

Model-based Analysis of the Pharmacokinetic Interactions Between Ritonavir, Nelfinavir, and Saquinavir after Simultaneous and Staggered Oral Administration

Human Constitutive Androstane Receptor Mediates Induction of CYP2B6 Gene Expression by Phenytoin

A Novel Distal Enhancer Module Regulated by Pregnane X Receptor/Constitutive Androstane Receptor Is Essential for the Maximal Induction of CYP2B6 Gene Expression

Contact Info

Product

Resources

About