Evaluation of Microsomal Incubation Conditions on CYP3A4-Mediated Metabolism of Cyclosporine A by a Statistical Experimental Design

Hermann, Monica; Kase, Eili Tranheim; Molden, Espen; Christensen, Hege

doi:10.2174/138920006776359275

Cited by 15 publications

(11 citation statements)

References 22 publications

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“…Buffer concentration did not alter the ratio of several testosterone metabolites from purified rat CYP2A1, CYP2B1, and CYP2C11 [14] or of midazolam metabolites from human liver microsomes [16], consistent with our findings that regioselectivity was insensitive to buffer concentration. However, a change in regioselectivity with pH was reported for the oxidation of testosterone by rat CYP2A1, CYP2B1, and CYP2C11 [14] and for cyclosporine metabolism of human CYP3A4 [15]. Likewise, our results revealed a change in regioselectivity with pH and additionally with buffer type.…”

Section: Discussionsupporting

confidence: 69%

Simultaneous measurement of CYP1A2 activity, regioselectivity, and coupling: Implications for environmental sensitivity of enzyme–substrate binding

Traylor

Chai

Clark

2011

Archives of Biochemistry and Biophysics

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The cytochrome P450 (CYP) reaction mechanism often yields a broad array of coupled and uncoupled products from a single substrate. While it is well known that reaction conditions can drastically affect the rate of P450 catalysis, their effects on regioselectivity and coupling are not well characterized. To investigate such effects, the CYP1A2 oxidation of 7-ethoxymethoxy-3-cyanocoumarin (EOMCC) was examined as a function of buffer type, buffer concentration, pH, and temperature. A high-throughput, optical method was developed to simultaneously measure the rate of substrate depletion, NADPH depletion, and generation of the O-dealkylated product. Increasing the phosphate buffer concentration and temperature increased both the NADPH and EOMCC depletion rates by 6-fold, whereas coupling was constant at 7.9% and the regioselectivity of O-dealkylation to other coupled pathways was constant at 21.7%. Varying the buffer type and pH increased NADPH depletion by 2.5-fold and EOMCC depletion by 3.5-fold; however, neither coupling nor regioselectivity was constant, with variations of 14.4% and 21.6%, respectively. Because the enzyme-substrate binding interaction is a primary determinant of both coupling and regioselectivity, it is reasonable to conclude that ionic strength, as varied by the buffer concentration, and temperature alter the rate without affecting binding while buffer type and pH alter both.

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Section: Discussionsupporting

confidence: 69%

Simultaneous measurement of CYP1A2 activity, regioselectivity, and coupling: Implications for environmental sensitivity of enzyme–substrate binding

Traylor

Chai

Clark

2011

Archives of Biochemistry and Biophysics

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“…Two oral curves could not be obtained because of discontinued consent and discharge of the patient, respectively. Other samples were missing because of transfer (4), discharge (1), clotted peripheral venous cannula (5) and other sampling problems (10). The CsA whole blood 12 h concentration profiles for all patients are shown in Figure 1.…”

Section: Resultsmentioning

confidence: 99%

“…The pharmacodynamics and pharmacokinetics of CsA are complex and, as a result, drug exposure is difficult to predict. CsA is extensively metabolized by cytochrome P4503A enzymes in the gut and liver to numerous active and inactive metabolites [5,6]. P-glycoprotein (P-gp) is the main transporter involved in CsA absorption and disposition [7].…”

Section: Introductionmentioning

confidence: 99%

Population pharmacokinetics of ciclosporin in haematopoietic allogeneic stem cell transplantation with emphasis on limited sampling strategy

Wilhelm¹,

Graaf²,

Veldkamp³

et al. 2012

Brit J Clinical Pharma

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WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT• The population pharmacokinetics and limited sampling strategies for ciclosporin monitoring have been extensively studied in renal and liver transplant recipients. Little is known about the pharmacokinetics of ciclosporin in patients undergoing haematopoietic allogeneic stem cell transplantation (HSCT).• It is anticipated that there is a difference in pharmacokinetics in patients after kidney or liver transplantation compared with patients undergoing stem cell transplantation, because of mucositis and interacting drugs (e.g. fluconazole).• Data on the pharmacokinetics of ciclosporin and the relationship between its systemic exposure, as reflected by the area under the curve (AUC), and the biological effect as graft vs. host-disease (GVHD) prophylaxis and graft vs. tumour (GVT) response are scarce in patients after HSCT. WHAT THIS STUDY ADDS• A pharmacokinetic model was developed for orally and intravenously administered ciclosporin, enabling an adequate estimate of the systemic exposure of ciclosporin in patients after HSCT. A limited sampling strategy was tested that may serve as a tool to study the optimum systemic exposure (AUC) of ciclosporin in HSCT to prevent GVHD but establish adequate GVT response and to guide therapeutic drug monitoring. AIMTo develop a population pharmacokinetic model of ciclosporin (CsA) in haematopoietic allogeneic stem cell transplantation to facilitate a limited sampling strategy to determine systemic exposure (area under the curve [AUC]), in order to optimize CsA therapy in this patient population. METHODSThe pharmacokinetics of CsA were investigated prospectively in 20 patients following allogeneic haematopoietic stem cell transplantation (HSCT). CsA was given twice daily, as a 3 h i.v. infusion starting at day 1 of the conditioning scheme, and orally later on, when oral intake was well tolerated. Fluconazole was given as antimycotic prophylaxis. Pharmacokinetic parameter estimation was performed using nonlinear mixed effect modelling as implemented in the NONMEM program. A first order absorption model with lag time was compared with Erlang frequency distribution and Weibull distribution models. The influence of demographic variables on the individual empirical Bayesian estimates of clearance and distribution volume was tested. Subsequently two limited sampling strategies (LSS) were evaluated: posterior Bayesian fitting and limited sampling equations. RESULTSTwenty patients were included and 435 samples were collected after i.v. and oral administration of CsA. A two compartment model with first order absorption best described the data. Clearance (CL) was 21.9 l h -1 (relative standard deviation [RSD] Ϯ 5.2%) with an inter-individual variability of 21%. The central volume of distribution (Vc) was 18.3 l (RSD Ϯ 8.7%) with an inter-individual variability of 29%. Bioavailability (F) was 0.71 (RSD Ϯ 9.9%) with and inter-individual variability of 25% and lag time (tlag) was 0.44 h (RSD 5.5%). Weight, body surface area, haematocrit, albumin, ALAT...

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“…Quetiapine (1 M for CYP3A4 and 5 M for CYP3A5) was incubated at 37°C in 118 mM Tris-H 2 SO 4 (pH 7.5), 0.5 mM MgSO 4 , and 1.6 mM NADPH, incubation conditions that were optimized by Hermann et al (2006). Microsomes were diluted in a solution (pH 7.4) consisting of 0.25 M sucrose, 10 mM Hepes, and 2 mM EDTA.…”

Section: Methodsmentioning

confidence: 99%

Metabolism of Quetiapine by CYP3A4 and CYP3A5 in Presence or Absence of Cytochrome B₅

Bakken¹,

Rudberg²,

Christensen³

et al. 2008

Drug Metab Dispos

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ABSTRACT:The antipsychotic drug quetiapine is extensively metabolized by CYP3A4, but little is known about the possible influence of the polymorphic enzyme CYP3A5. This in vitro study investigated the relative importance of CYP3A4 and CYP3A5 in the metabolism of quetiapine and compared the metabolic pattern by the two enzymes, in the presence or absence of cytochrome b 5 . Intrinsic clearance (CL int ) of quetiapine was determined by the substrate depletion approach in CYP3A4 and CYP3A5 insect cell microsomes with or without coexpressed cytochrome b 5 . Formation of the metabolites quetiapine sulfoxide, N-desalkylquetiapine, O-desalkylquetiapine, and 7-hydroxyquetiapine by CYP3A4 and CYP3A5 were compared in the different microsomal preparations. CL int of quetiapine by CYP3A5 was less than 35% relative to CYP3A4. Quetiapine, a dibenzothiazepine derivative, is an atypical antipsychotic drug used for the treatment of schizophrenia and acute episodes of mania. Recently, the U.S. Food and Drug Administration also approved quetiapine for the treatment of depressive episodes associated with bipolar disorder.Quetiapine is extensively metabolized in the liver by the cytochrome P450 (P450) system, primarily by CYP3A (Grimm et al., 1997(Grimm et al., , 2006. The major metabolic pathways of quetiapine are through sulfoxidation, N-and O-dealkylation, and, to a lesser degree, through 7-hydroxylation (Grimm et al., 1997) (Fig. 1). The pharmacologically inactive metabolite quetiapine sulfoxide is considered to be the main metabolite of quetiapine (DeVane and Nemeroff, 2001), whereas the most important active metabolite seems to be N-desalkylquetiapine (McIntyre et al., 2007). Studies indicate that N-desalkylquetiapine, unlike the parent compound, is a potent inhibitor of the noradrenergic transporter and has partial agonist activity at the 5-hydroxytryptamine 1A receptor (Goldstein et al., 2007;Jensen et al., 2008). In addition, N-desalkylquetiapine was found to possess antidepressive-like activity in a mouse model (Jensen et al., 2008). This suggests that the antidepressive activity of quetiapine is, at least partly, mediated by N-desalkylquetiapine. The active metabolite 7-hydroxyquetiapine is formed by CYP2D6 in addition to by CYP3A (Grimm et al., 2006). Because of the low plasma concentration of this metabolite (Gefvert et al., 1998), genetic polymorphism in CYP2D6 is unlikely to be of importance for the in vivo metabolism of quetiapine.CYP3A4 and CYP3A5 comprise the two main CYP3A isoforms in adults. The individual variability in phenotype is substantial for both enzymes, but this variability is linked to genetic polymorphism only for CYP3A5 (Westlind-Johnsson et al., 2003). CYP3A5 is expressed in approximately 10 to 30% of whites, 30% of Japanese, and 60% of African Americans (Kuehl et al., 2001;Burk and Wojnowski, 2004). The relative contribution of CYP3A5 to total hepatic CYP3A protein differs, but in some individuals CYP3A5 can constitute more than 50% of total CYP3A (Kuehl et al., 2001;Lin et al., 2002; WestlindJohns...

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Evaluation of Microsomal Incubation Conditions on CYP3A4-Mediated Metabolism of Cyclosporine A by a Statistical Experimental Design

Cited by 15 publications

References 22 publications

Simultaneous measurement of CYP1A2 activity, regioselectivity, and coupling: Implications for environmental sensitivity of enzyme–substrate binding

Simultaneous measurement of CYP1A2 activity, regioselectivity, and coupling: Implications for environmental sensitivity of enzyme–substrate binding

Population pharmacokinetics of ciclosporin in haematopoietic allogeneic stem cell transplantation with emphasis on limited sampling strategy

Metabolism of Quetiapine by CYP3A4 and CYP3A5 in Presence or Absence of Cytochrome B₅

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Evaluation of Microsomal Incubation Conditions on CYP3A4-Mediated Metabolism of Cyclosporine A by a Statistical Experimental Design

Cited by 15 publications

References 22 publications

Simultaneous measurement of CYP1A2 activity, regioselectivity, and coupling: Implications for environmental sensitivity of enzyme–substrate binding

Simultaneous measurement of CYP1A2 activity, regioselectivity, and coupling: Implications for environmental sensitivity of enzyme–substrate binding

Population pharmacokinetics of ciclosporin in haematopoietic allogeneic stem cell transplantation with emphasis on limited sampling strategy

Metabolism of Quetiapine by CYP3A4 and CYP3A5 in Presence or Absence of Cytochrome B5

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Metabolism of Quetiapine by CYP3A4 and CYP3A5 in Presence or Absence of Cytochrome B₅