1
|
Ferlini Agne G, Somogyi AA, Sykes B, Knych H, Franklin S. Identification and kinetics of microsomal and recombinant equine liver cytochrome P450 enzymes responsible for in vitro metabolism of omeprazole. Biochem Pharmacol 2023:115635. [PMID: 37285945 DOI: 10.1016/j.bcp.2023.115635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 05/26/2023] [Accepted: 05/31/2023] [Indexed: 06/09/2023]
Abstract
In humans, omeprazole is metabolised by cytochrome P450 (CYP450) CYP2C19 and CYP3A4 with differences in CYP2C19 genotypes leading to variable response to therapy. Despite a wide use of omeprazole in horses with evidence of variable therapeutic efficiency, information regarding enzymatic metabolism is not currently available. This study aims to describe the in vitro kinetics of omeprazole metabolism and determine which enzyme(s) are responsible for omeprazole metabolism in horses. Omeprazole (0-800 uM) was incubated with liver microsomes and a panel of equine recombinant CYP450s (eq-rCYP). Metabolite concentrations were quantified by LC-MS and the kinetics of metabolites' formation were calculated by non-linear regression analysis. The in vitro liver microsomes formed three metabolites (5-hydroxy-omeprazole, 5-O-desmethyl-omeprazole and omeprazole-sulfone). The 5-O-desmesthyl-omeprazole formation was best fitted to a two enzyme Michaelis-Menten (MM) model with the high affinity site Clint double that of the low affinity site. For 5-hydroxy-omeprazole the best fit was to a 1 enzyme MM model with a Clint higher than for 5-O-desmesthyl-omeprazole (0.12 vs 0.09 pmol/min/pmol P450). The formation of omeprazole-sulfone was negligible. Recombinant CYP3A89 and CYP3A97 produced substantial amounts of 5-hydroxy-omeprazole (1551.72 ng/mL and 1665.33 ng/mL, respectively), while 5-O-desmethyl-omeprazole and omeprazole-sulfone were formed to a much lesser extent by multiple eq-rCYP from the CYP2C and CYP3A family. In vitro metabolism of omeprazole in horses is different to that in humans, with major metabolites produced by the CYP3A family. The current study provides the basis for further investigations of CYP450 single nucleotide polymorphisms that could affect omeprazole metabolism and therapeutic efficacy.
Collapse
Affiliation(s)
- Gustavo Ferlini Agne
- School of Animal and Veterinary Sciences, University of Adelaide, Roseworthy, South Australia, Australia.
| | - Andrew A Somogyi
- Discipline of Pharmacology, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - Ben Sykes
- School of Veterinary Medicine, Massey University, Palmerston North, NZ
| | - Heather Knych
- K.L. Maddy Equine Analytical Pharmacology Laboratory, School of Veterinary Medicine, University of California-Davis, Davis, CA, USA
| | - Samantha Franklin
- School of Animal and Veterinary Sciences, University of Adelaide, Roseworthy, South Australia, Australia
| |
Collapse
|
2
|
Resina L, El Hauadi K, Sans J, Esteves T, Ferreira FC, Pérez-Madrigal MM, Alemán C. Electroresponsive and pH-Sensitive Hydrogel as Carrier for Controlled Chloramphenicol Release. Biomacromolecules 2023; 24:1432-1444. [PMID: 36821593 PMCID: PMC10889591 DOI: 10.1021/acs.biomac.2c01442] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Multiresponsive hydrogels, which are smart soft materials that respond to more than one external stimulus, have emerged as powerful tools for biomedical applications, such as drug delivery. Within this context and with the aim of eliminating the systematic administration of antibiotics, special attention is being paid to the development of systems for controlled delivery of antibiotic for topical treatment of bacterial infections. In this work, an electro-chemo responsive hydrogel able to release chloramphenicol (CAM), a broad spectrum antibiotic also used for anticancer therapy, is proposed. This has been prepared by grafting poly(acrylic acid) (PAA) to sodium alginate (Alg) and in situ encapsulation of poly(3,4-ethylenedioxythiophene) nanoparticles loaded with CAM (PEDOT/CAM NPs), which were obtained by emulsion polymerization. Although the response to electrical stimuli of PEDOT was the main control for the release of CAM from PEDOT/CAM NPs, the release by passive diffusion had a relatively important contribution. Conversely, the passive release of antibiotic from the whole engineered hydrogel system, Alg-g-PAA/PEDOT/CAM, was negligible, whereas significant release was achieved under electrostimulation in an acid environment. Bacterial tests and assays with cancer cells demonstrated that the biological activity of CAM remained after release by electrical stimulation. Notably, the successful dual-response of the developed hydrogel to electrical stimuli and pH changes evidence the great prospect of this smart material in the biomedical field, as a tool to fight against bacterial infections and to provide local cancer treatment.
Collapse
Affiliation(s)
- Leonor Resina
- Departament d'Enginyeria Química and Barcelona Research Center for Multiscale Science and Engineering, EEBE, Universitat Politècnica de Catalunya, C/Eduard Maristany 10-14, 08019 Barcelona, Spain
- iBB - Institute for Bioengineering and Biosciences, Department of Bioengineering, Instituto Superior Técnico - Universidade de Lisboa, Avenida Rovisco Pais 1, 1049-001 Lisboa, Portugal
- Associate Laboratory i4HB-Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Avenida Rovisco Pais 1, 1049-001 Lisboa, Portugal
| | - Karima El Hauadi
- Departament d'Enginyeria Química and Barcelona Research Center for Multiscale Science and Engineering, EEBE, Universitat Politècnica de Catalunya, C/Eduard Maristany 10-14, 08019 Barcelona, Spain
| | - Jordi Sans
- Departament d'Enginyeria Química and Barcelona Research Center for Multiscale Science and Engineering, EEBE, Universitat Politècnica de Catalunya, C/Eduard Maristany 10-14, 08019 Barcelona, Spain
| | - Teresa Esteves
- iBB - Institute for Bioengineering and Biosciences, Department of Bioengineering, Instituto Superior Técnico - Universidade de Lisboa, Avenida Rovisco Pais 1, 1049-001 Lisboa, Portugal
- Associate Laboratory i4HB-Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Avenida Rovisco Pais 1, 1049-001 Lisboa, Portugal
| | - Frederico Castelo Ferreira
- iBB - Institute for Bioengineering and Biosciences, Department of Bioengineering, Instituto Superior Técnico - Universidade de Lisboa, Avenida Rovisco Pais 1, 1049-001 Lisboa, Portugal
- Associate Laboratory i4HB-Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Avenida Rovisco Pais 1, 1049-001 Lisboa, Portugal
| | - Maria M Pérez-Madrigal
- Departament d'Enginyeria Química and Barcelona Research Center for Multiscale Science and Engineering, EEBE, Universitat Politècnica de Catalunya, C/Eduard Maristany 10-14, 08019 Barcelona, Spain
| | - Carlos Alemán
- Departament d'Enginyeria Química and Barcelona Research Center for Multiscale Science and Engineering, EEBE, Universitat Politècnica de Catalunya, C/Eduard Maristany 10-14, 08019 Barcelona, Spain
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, 08028 Barcelona, Spain
| |
Collapse
|
3
|
Shruthi E, Yallappa S, Mallikarjuna NM, Talavara V, Dhananjaya BL, Vaidya VP. 8‐Nitronaphthofuran Fused Urea Derivatives as Potential Antimicrobial Agents: Synthesis, Characterization and Pharmacological Studies. ChemistrySelect 2023. [DOI: 10.1002/slct.202204979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Affiliation(s)
- E. Shruthi
- Department of Chemistry Kuvempu University Shankaraghatta 577451, Shivammoga District Karnataka India
| | - S. Yallappa
- Department of Chemistry AMC Engineering College Bangalore 560083 Karnataka India
| | - N. M. Mallikarjuna
- Department of Chemistry Kuvempu University Shankaraghatta 577451, Shivammoga District Karnataka India
| | - V. Talavara
- Department of Chemistry Kuvempu University Shankaraghatta 577451, Shivammoga District Karnataka India
| | - B. L. Dhananjaya
- Toxicology and Drug Discovery Unit Jain University Jakksandra post, Kanakapura Taluk Ramanagara 562112 Karnataka India
| | - V. P. Vaidya
- Department of Chemistry Kuvempu University Shankaraghatta 577451, Shivammoga District Karnataka India
| |
Collapse
|
4
|
Chen CJ, Gillett A, Booth R, Kimble B, Govendir M. Pharmacokinetic Profile of Doxycycline in Koala Plasma after Weekly Subcutaneous Injections for the Treatment of Chlamydiosis. Animals (Basel) 2022; 12:ani12030250. [PMID: 35158574 PMCID: PMC8833767 DOI: 10.3390/ani12030250] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/14/2022] [Accepted: 01/17/2022] [Indexed: 11/16/2022] Open
Abstract
Simple Summary Doxycycline is an antimicrobial used for treating chlamydial infections in various species, including the koala. The dose and route of administration used initially are based on first principles. Therefore, this study investigates the absorption, distribution, metabolism, and excretion of subcutaneous doxycycline injections, and evaluates the suitability of the current dosage regimen for inhibiting chlamydial pathogens. The results suggest that the current doxycycline dosage remained therapeutically effective for up to six days after each dose, with some accumulation over successive doses. All koalas in the study improved clinically and tested negative for chlamydial pathogens post-treatment before being released. This study contributes to determining the optimal dosage of doxycycline to treat chlamydiosis safely and effectively in infected koalas. Abstract Six mature, male koalas (Phascolarctos cinereus), with clinical signs of chlamydiosis, were administered doxycycline as a 5 mg/kg subcutaneous injection, once a week for four weeks. Blood was collected at standardised time points (T = 0 to 672 h) to quantify the plasma doxycycline concentrations through high-pressure liquid chromatography (HPLC). In five koalas, the doxycycline plasma concentration over the first 48 h appeared to have two distinct elimination gradients; therefore, a two-compartmental analysis was undertaken to describe the pharmacokinetic (PK) profile. The average ± SD maximum plasma concentration (Cmax) was 312.30 ± 107.74 ng/mL, while the average time ± SD taken to reach the maximum plasma concentration (Tmax) was 1.68 ± 1.49 h. The mean ± SD half-life of the distribution phase (T1/2 α) and the elimination phase (T1/2 β) were 10.51 ± 7.15 h and 82.93 ± 37.76 h, respectively. The average ± SD percentage of doxycycline binding to koala plasma protein was 83.65 ± 4.03% at three different concentrations, with a mean unbound fraction (fu) of 0.16. Using probability of target attainment modelling, doxycycline plasma concentrations were likely to inhibit 90% of pathogens with the doxycycline minimum inhibitory concentration (MIC) of 8.0–31.0 ng/mL, and the reported doxycycline MIC to inhibit Chlamydia pecorum isolates at the area under the curve/minimum inhibitory concentration (AUC/MIC) target of ≥24. All koalas were confirmed to be negative for Chlamydia pecorum using loop-mediated isothermal amplification (LAMP), from ocular and penile urethra swabs, three weeks after the last doxycycline injection.
Collapse
Affiliation(s)
- Chien-Jung Chen
- Sydney School of Veterinary Science, The University of Sydney, Sydney, NSW 2006, Australia; (B.K.); (M.G.)
- Correspondence:
| | - Amber Gillett
- Australia Zoo Wildlife Hospital, Beerwah, QLD 4519, Australia; (A.G.); (R.B.)
| | - Rosemary Booth
- Australia Zoo Wildlife Hospital, Beerwah, QLD 4519, Australia; (A.G.); (R.B.)
| | - Benjamin Kimble
- Sydney School of Veterinary Science, The University of Sydney, Sydney, NSW 2006, Australia; (B.K.); (M.G.)
| | - Merran Govendir
- Sydney School of Veterinary Science, The University of Sydney, Sydney, NSW 2006, Australia; (B.K.); (M.G.)
| |
Collapse
|
5
|
Kawahara B, Faull KF, Janzen C, Mascharak PK. Carbon Monoxide Inhibits Cytochrome P450 Enzymes CYP3A4/2C8 in Human Breast Cancer Cells, Increasing Sensitivity to Paclitaxel. J Med Chem 2021; 64:8437-8446. [PMID: 34097831 DOI: 10.1021/acs.jmedchem.1c00404] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Paclitaxel (PTX) is a first-line treatment in breast cancer, though resistance develops quickly and frequently. Cytochrome P450 enzymes CYP3A4 and CYP2C8, which metabolically inactivate PTX in hepatic tissue, are overexpressed in malignant breast tissues. CYP3A4 expression correlates with PTX therapy failure and poor outcomes, though no direct evidence of CYP3A4 contributing to PTX sensitivity exists. Because CYP3A4/2C8 is susceptible to carbon monoxide (CO)-mediated inhibition and CO (a gaseous signaling molecule) has previously exhibited drug-sensitizing effects in cancer cells, we hypothesized that CO-mediated inhibition of CYP3A4/2C8 could lead to enhanced drug sensitivity. Using a photo-activated CO-releasing molecule, we have assessed the ability of CO to alter the pharmacokinetics of PTX in breast cancer cells via inhibition of CYP3A4/2C8 and determined that CO does enhance sensitivity of breast cancer cells to PTX. Inhibition of CYP3A4/2C8 by CO could therefore be a promising therapeutic strategy to enhance PTX response in breast cancer.
Collapse
Affiliation(s)
- Brian Kawahara
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, California 95064, United States
| | - Kym F Faull
- Pasarow Mass Spectrometry Laboratory, Jane and Terry Semel Institute for Neuroscience and Human Behavior and Department of Psychiatry & Biobehavioral Sciences, David Geffen School of Medicine at UCLA, Los Angeles, California 90024, United States
| | - Carla Janzen
- Department of Obstetrics and Gynecology, David Geffen School of Medicine at University of California at Los Angeles, Los Angeles, California 90095, United States
| | - Pradip K Mascharak
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, California 95064, United States
| |
Collapse
|
6
|
Shibany KA, Pratt SL, Aldurdunji M, Totemeyer S, Paine SW. Prediction of pharmacokinetic clearance and potential Drug-Drug interactions for omeprazole in the horse using in vitro systems. Xenobiotica 2020; 50:1220-1227. [PMID: 32369392 DOI: 10.1080/00498254.2020.1764131] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Horses are exposed to various kinds of medication, however, there are limited determinations of plasma clearance (CLp) for the drugs used due to the high cost of equine in vivo studies.Many of the CLp values generated come from the equine sports industry for determining drug plasma screening limits in the control of medications at the time of competition.The kinetics of omeprazole metabolism were investigated in freshly isolated and cryopreserved equine hepatocytes and hepatic microsomes (n = 3 horses).The Vmax, Km and intrinsic clearance (CLint) of omeprazole were determined via the substrate depletion method as well as Km values for the formation of three metabolites.The CLint values were extrapolated to in vivo hepatic plasma clearance (CLH) using the well stirred and parallel tube models.Clp for omeprazole was successfully predicted using freshly isolated or cryopreserved equine hepatocytes, while microsomes under-predicted.Equine microsomes were used to perform a drug-drug interaction (DDI) study between omeprazole and chloramphenicol. The average inhibitor constant Ki, assuming competitive inhibition, was 15.4 ± 5 µM.To the authors' knowledge, this is the first report showing the successful extrapolation of drug CLp in the horse using equine hepatocytes and the prediction of a DDI using microsomes.
Collapse
Affiliation(s)
- Khaled A Shibany
- School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, Loughborough, United Kingdom of Great Britain and Northern Ireland
| | - Stefanie L Pratt
- School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, Loughborough, United Kingdom of Great Britain and Northern Ireland
| | - Mohammed Aldurdunji
- School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, Loughborough, United Kingdom of Great Britain and Northern Ireland
| | - Sabine Totemeyer
- School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, Loughborough, United Kingdom of Great Britain and Northern Ireland
| | - Stuart W Paine
- School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, Loughborough, United Kingdom of Great Britain and Northern Ireland
| |
Collapse
|
7
|
Estell K, Knych H, Patel T, Edman J, Magdesian K. Pharmacokinetics of multiple doses of chloramphenicol in fed adult horses. Vet J 2020; 257:105446. [DOI: 10.1016/j.tvjl.2020.105446] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 02/19/2020] [Accepted: 02/19/2020] [Indexed: 10/25/2022]
|
8
|
Patel T, Magdesian KG, Estell KE, Edman JM, Knych HK. Pharmacokinetics of chloramphenicol base in horses and comparison to compounded formulations. J Vet Pharmacol Ther 2019; 42:609-616. [PMID: 31162675 DOI: 10.1111/jvp.12777] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 04/17/2019] [Accepted: 04/26/2019] [Indexed: 11/29/2022]
Abstract
Chloramphenicol is commonly used in horses; however, there are no studies evaluating the pharmacokinetics of veterinary canine-approved tablets. Studies using different formulations and earlier analytical techniques led to concerns over low bioavailability in horses. Safety concerns about human health have led many veterinarians to prescribe compounded formulations that are already in suspension or paste form. The objective of this study was to evaluate the pharmacokinetics of approved chloramphenicol tablets in horses, along with compounded preparations. The hypothesis was that chloramphenicol has low absorption and a short half-life in horses leading to low serum concentrations and that compounded preparations have lower relative bioavailability. Seven horses were administered chloramphenicol tablets (50 mg/kg orally). In a crossover design, they were administered two compounded preparations to compare all three formulations at the same dose (50 mg/kg). Cmax was 5.25 ± 4.07 μg/ml at 4.89 hr, 4.96 ± 3.31 μg/ml at 4.14 hr, and 3.84 ± 2.96 μg/ml at 4.39 hr for the tablets, paste, and suspension, respectively. Elimination half-life was 2.65 ± 0.75, 3.47 ± 1.47, and 4.36 ± 4.54 hr for tablets, paste, and suspension, respectively. The AUC0→∞ was 17.93 ± 7.69, 16.25 ± 1.85, and 14.00 ± 5.47 hr*μg/ml for the tablets, compounded paste, and compounded suspension, respectively. Relative bioavailability of compounded suspension and paste was 78.1% and 90.6%. Cmax after administration of all formulations did not reach the recommended MIC target of 8 μg/ml set by the Clinical Laboratory Standards Institute (CLSI) for most bacteria. Multidose studies are warranted, but the low serum concentrations suggest that bacteria with MIC values lower than CLSI recommendations should be targeted in adult horses.
Collapse
Affiliation(s)
- Trishna Patel
- William R. Pritchard Veterinary Medical Teaching Hospital, University of California, Davis, California
| | - K Gary Magdesian
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California
| | - Krista E Estell
- William R. Pritchard Veterinary Medical Teaching Hospital, University of California, Davis, California
| | - Judy M Edman
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California
| | - Heather K Knych
- Kenneth L. Maddy Equine Analytical Chemistry Laboratory, School of Veterinary Medicine, University of California, Davis, California
| |
Collapse
|
9
|
Cytochrome P450 inhibition potential of new psychoactive substances of the tryptamine class. Toxicol Lett 2016; 241:82-94. [DOI: 10.1016/j.toxlet.2015.11.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 11/09/2015] [Accepted: 11/13/2015] [Indexed: 11/20/2022]
|
10
|
Dinger J, Meyer MR, Maurer HH. In vitro cytochrome P450 inhibition potential of methylenedioxy-derived designer drugs studied with a two-cocktail approach. Arch Toxicol 2014; 90:305-18. [PMID: 25417051 DOI: 10.1007/s00204-014-1412-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 11/06/2014] [Indexed: 11/25/2022]
Abstract
In vitro cytochrome P450 (CYP) inhibition assays are common approaches for testing the inhibition potential of drugs for predicting potential interactions. In contrast to marketed medicaments, drugs of abuse, particularly the so-called novel psychoactive substances, were not tested before distribution and consumption. Therefore, the inhibition potential of methylenedioxy-derived designer drugs (MDD) of different drug classes such as aminoindanes, amphetamines, benzofurans, cathinones, piperazines, pyrrolidinophenones, and tryptamines should be elucidated. The FDA-preferred test substrates, split in two cocktails, were incubated with pooled human liver microsomes and analysed after protein precipitation using LC-high-resolution-MS/MS. IC50 values were determined of MDD showing more than 50 % inhibition in the prescreening. Values were calculated by plotting the relative metabolite concentration formed over the logarithm of the inhibitor concentration. All MDD showed inhibition against CYP2D6 activity and most of them in the range of the clinically relevant CYP2D6 inhibitors quinidine and fluoxetine. In addition, the beta-keto compounds showed inhibition of the activity of CYP2B6, 5,6-MD-DALT of CYP1A2 and CYP3A, and MDAI of CYP2A6, all in the range of clinically relevant inhibitors. In summary, all MDD showed inhibition of the activity of CYP2D6, six of CYP1A2, three of CYP2A6, 13 of CYP2B6, two of CYP2C9, six of CYP2C19, one of CYP2E1, and six of CYP3A. These results showed that the CYP inhibition by MDD might be clinically relevant, but further studies are needed for final conclusions.
Collapse
Affiliation(s)
- Julia Dinger
- Department of Experimental and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Saarland University, 66421, Homburg, Saar, Germany
| | - Markus R Meyer
- Department of Experimental and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Saarland University, 66421, Homburg, Saar, Germany
| | - Hans H Maurer
- Department of Experimental and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Saarland University, 66421, Homburg, Saar, Germany.
| |
Collapse
|
11
|
|
12
|
Development of an in vitro cytochrome P450 cocktail inhibition assay for assessing the inhibition risk of drugs of abuse. Toxicol Lett 2014; 230:28-35. [DOI: 10.1016/j.toxlet.2014.08.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 08/05/2014] [Accepted: 08/07/2014] [Indexed: 11/18/2022]
|
13
|
Foster SR, Blank K, Hoe LES, Behrens M, Meyerhof W, Peart JN, Thomas WG. Bitter taste receptor agonists elicit G‐protein‐dependent negative inotropy in the murine heart. FASEB J 2014; 28:4497-508. [DOI: 10.1096/fj.14-256305] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Simon R. Foster
- School of Biomedical SciencesUniversity of QueenslandBrisbaneQueenslandAustralia
| | - Kristina Blank
- Department of Molecular GeneticsGerman Institute of Human Nutrition (DIfE) Potsdam‐RehbrückeNuthetalGermany
| | - Louise E. See Hoe
- Griffith Health InstituteGriffith UniversityGold CoastQueenslandAustralia
| | - Maik Behrens
- Department of Molecular GeneticsGerman Institute of Human Nutrition (DIfE) Potsdam‐RehbrückeNuthetalGermany
| | - Wolfgang Meyerhof
- Department of Molecular GeneticsGerman Institute of Human Nutrition (DIfE) Potsdam‐RehbrückeNuthetalGermany
| | - Jason N. Peart
- Griffith Health InstituteGriffith UniversityGold CoastQueenslandAustralia
| | - Walter G. Thomas
- School of Biomedical SciencesUniversity of QueenslandBrisbaneQueenslandAustralia
| |
Collapse
|
14
|
Janha RE, Worwui A, Linton KJ, Shaheen SO, Sisay-Joof F, Walton RT. Inactive alleles of cytochrome P450 2C19 may be positively selected in human evolution. BMC Evol Biol 2014; 14:71. [PMID: 24690327 PMCID: PMC4036532 DOI: 10.1186/1471-2148-14-71] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 03/25/2014] [Indexed: 12/27/2022] Open
Abstract
Background Cytochrome P450 CYP2C19 metabolizes a wide range of pharmacologically active substances and a relatively small number of naturally occurring environmental toxins. Poor activity alleles of CYP2C19 are very frequent worldwide, particularly in Asia, raising the possibility that reduced metabolism could be advantageous in some circumstances. The evolutionary selective forces acting on this gene have not previously been investigated. We analyzed CYP2C19 genetic markers from 127 Gambians and on 120 chromosomes from Yoruba, Europeans and Asians (Japanese + Han Chinese) in the Hapmap database. Haplotype breakdown was explored using bifurcation plots and relative extended haplotype homozygosity (REHH). Allele frequency differentiation across populations was estimated using the fixation index (FST) and haplotype diversity with coalescent models. Results Bifurcation plots suggested conservation of alleles conferring slow metabolism (CYP2C19*2 and *3). REHH was high around CYP2C19*2 in Yoruba (REHH 8.3, at 133.3 kb from the core) and to a lesser extent in Europeans (3.5, at 37.7 kb) and Asians (2.8, at −29.7 kb). FST at the CYP2C19 locus was low overall (0.098). CYP2C19*3 was an FST outlier in Asians (0.293), CYP2C19 haplotype diversity < = 0.037, p <0.001. Conclusions We found some evidence that the slow metabolizing allele CYP2C19*2 is subject to positive selective forces worldwide. Similar evidence was also found for CYP2C19*3 which is frequent only in Asia. FST is low at the CYP2C19 locus, suggesting balancing selection overall. The biological factors responsible for these selective pressures are currently unknown. One possible explanation is that early humans were exposed to a ubiquitous novel toxin activated by CYP2C19. The genetic adaptation took place within the last 10,000 years which coincides with the development of systematic agricultural practices.
Collapse
|
15
|
Sun X, Ai M, Wang Y, Shen S, Gu Y, Jin Y, Zhou Z, Long Y, Yu Q. Selective induction of tumor cell apoptosis by a novel P450-mediated reactive oxygen species (ROS) inducer methyl 3-(4-nitrophenyl) propiolate. J Biol Chem 2013; 288:8826-37. [PMID: 23382387 DOI: 10.1074/jbc.m112.429316] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Induction of tumor cell apoptosis has been recognized as a valid anticancer strategy. However, therapeutic selectivity between tumor and normal cells has always been a challenge. Here, we report a novel anti-cancer compound methyl 3-(4-nitrophenyl) propiolate (NPP) preferentially induces apoptosis in tumor cells through P450-catalyzed reactive oxygen species (ROS) production. A compound sensitivity study on multiple cell lines shows that tumor cells with high basal ROS levels, low antioxidant capacities, and p53 mutations are especially sensitive to NPP. Knockdown of p53 sensitized non-transformed cells to NPP-induced cell death. Additionally, by comparing NPP with other ROS inducers, we show that the susceptibility of tumor cells to the ROS-induced cell death is influenced by the mode, amount, duration, and perhaps location of ROS production. Our studies not only discovered a unique anticancer drug candidate but also shed new light on the understanding of ROS generation and function and the potential application of a ROS-promoting strategy in cancer treatment.
Collapse
Affiliation(s)
- Xiaoxiao Sun
- Departments of Pharmacology, Chinese Academy of Sciences, 555 Zhchongzhi Road, Shanghai, China 201203
| | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Schiffman SS, Rother KI. Sucralose, a synthetic organochlorine sweetener: overview of biological issues. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART B, CRITICAL REVIEWS 2013; 16:399-451. [PMID: 24219506 PMCID: PMC3856475 DOI: 10.1080/10937404.2013.842523] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Sucralose is a synthetic organochlorine sweetener (OC) that is a common ingredient in the world's food supply. Sucralose interacts with chemosensors in the alimentary tract that play a role in sweet taste sensation and hormone secretion. In rats, sucralose ingestion was shown to increase the expression of the efflux transporter P-glycoprotein (P-gp) and two cytochrome P-450 (CYP) isozymes in the intestine. P-gp and CYP are key components of the presystemic detoxification system involved in first-pass drug metabolism. The effect of sucralose on first-pass drug metabolism in humans, however, has not yet been determined. In rats, sucralose alters the microbial composition in the gastrointestinal tract (GIT), with relatively greater reduction in beneficial bacteria. Although early studies asserted that sucralose passes through the GIT unchanged, subsequent analysis suggested that some of the ingested sweetener is metabolized in the GIT, as indicated by multiple peaks found in thin-layer radiochromatographic profiles of methanolic fecal extracts after oral sucralose administration. The identity and safety profile of these putative sucralose metabolites are not known at this time. Sucralose and one of its hydrolysis products were found to be mutagenic at elevated concentrations in several testing methods. Cooking with sucralose at high temperatures was reported to generate chloropropanols, a potentially toxic class of compounds. Both human and rodent studies demonstrated that sucralose may alter glucose, insulin, and glucagon-like peptide 1 (GLP-1) levels. Taken together, these findings indicate that sucralose is not a biologically inert compound.
Collapse
Affiliation(s)
- Susan S. Schiffman
- Department of Electrical and Computer Engineering, College of Engineering, North Carolina State University, Raleigh, North Carolina, USA
- Address correspondence to Susan S. Schiffman, PhD, Department of Electrical and Computer Engineering, College of Engineering, North Carolina State University, Raleigh, NC 27695-7911, USA. E-mail:
| | - Kristina I. Rother
- Section on Pediatric Diabetes & Metabolism, Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health, Bethesda, Maryland, USA
| |
Collapse
|
17
|
Wiest DB, Cochran JB, Tecklenburg FW. Chloramphenicol toxicity revisited: a 12-year-old patient with a brain abscess. J Pediatr Pharmacol Ther 2012; 17:182-8. [PMID: 23118672 DOI: 10.5863/1551-6776-17.2.182] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Chloramphenicol, a broad-spectrum antibiotic, is rarely used in the United States due to its well-described adverse effects. Because of its limited use, many clinicians are unfamiliar with its indications, spectrum of activity, and potential adverse drug effects. We describe a 12-year-old patient who presented after two craniotomies for a persistent brain abscess complicated by long-term chloramphenicol administration. Findings for this patient were consistent with many of the adverse drug effects associated with chloramphenicol, including elevated chloramphenicol serum concentrations, anemia, thrombocytopenia, reticulocytopenia, and severe metabolic acidosis. Rare manifestations of chloramphenicol toxicity that developed in this patient included neutropenia, visual field changes, and peripheral neuropathy. Chloramphenicol administration was discontinued, and hemodialysis was initiated for severe metabolic acidosis. The patient recovered with severe visual field deficits. Although chloramphenicol is rarely indicated, it remains an effective antibiotic. Healthcare providers should become familiar with the pharmacology, toxicology, and monitoring parameters for appropriate use of this antibiotic.
Collapse
Affiliation(s)
- Donald B Wiest
- Department of Clinical Pharmacy and Outcomes Sciences, South Carolina College of Pharmacy, Medical University of South Carolina, Charleston, South Carolina
| | | | | |
Collapse
|
18
|
Irving RM, Elfarra AA. Role of reactive metabolites in the circulation in extrahepatic toxicity. Expert Opin Drug Metab Toxicol 2012; 8:1157-72. [PMID: 22681489 DOI: 10.1517/17425255.2012.695347] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
INTRODUCTION Reactive metabolite-mediated toxicity is frequently limited to the organ where the electrophilic metabolites are generated. Some reactive metabolites, however, might have the ability to translocate from their site of formation. This suggests that for these reactive metabolites, investigations into the role of organs other than the one directly affected could be relevant to understanding the mechanism of toxicity. AREAS COVERED The authors discuss the physiological and biochemical factors that can enable reactive metabolites to cause toxicity in an organ distal from the site of generation. Furthermore, the authors present a case study which describes studies that demonstrate that S-(1,2-dichlorovinyl)-L-cysteine sulfoxide (DCVCS) and N-acetyl-S-(1,2-dichlorovinyl-L-cysteine sulfoxide (N-AcDCVCS), reactive metabolites of the known trichloroethylene metabolites S-(1,2-dichlorovinyl)-L-cysteine (DCVC), and N-acetyl-S-(1,2-dichlorovinyl)-L-cysteine (N-AcDCVC), are generated in the liver and translocate through the circulation to the kidney to cause nephrotoxicity. EXPERT OPINION The ability of reactive metabolites to translocate could be important to consider when investigating mechanisms of toxicity. A mechanistic approach, similar to the one described for DCVCS and N-AcDCVCS, could be useful in determining the role of circulating reactive metabolites in extrahepatic toxicity of drugs and other chemicals. If this is the case, intervention strategies that would not otherwise be feasible might be effective for reducing extrahepatic toxicity.
Collapse
Affiliation(s)
- Roy M Irving
- University of Wisconsin-Madison, School of Veterinary Medicine, Department of Comparative Biosciences and Molecular and Environmental Toxicology Center, Madison, WI 53706, USA
| | | |
Collapse
|
19
|
Man M, Farmen M, Dumaual C, Teng CH, Moser B, Irie S, Noh GJ, Njau R, Close S, Wise S, Hockett R. Genetic variation in metabolizing enzyme and transporter genes: comprehensive assessment in 3 major East Asian subpopulations with comparison to Caucasians and Africans. J Clin Pharmacol 2010; 50:929-40. [PMID: 20173083 DOI: 10.1177/0091270009355161] [Citation(s) in RCA: 167] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The advent of high-throughput technologies has proven valuable in the assessment of genetic differences and their effects on drug activation, metabolism, disposition, and transport. However, most studies to date have focused on a small number of genes or few alleles, some of which are rare and therefore observed infrequently or lacked rigorous ethnic characterization, thus reducing the ability to extrapolate within and among populations. In this study, the authors comprehensively assessed the allele frequencies of 165 variants comprising 27 drug-metabolizing enzyme and transporter (DMET) genes from 2188 participants across 3 major ethnic populations: Caucasians, Africans, and East Asians. This sample size was sufficiently large to demonstrate genetic differences among these major ethnic groups while concomitantly confirming similarities among East Asian subpopulations (Korean, Han Chinese, and Japanese). A comprehensive presentation of allele and genotype frequencies is included in the online supplement, and 3 of the most widely studied cytochrome P450 (CYP) genes, CYP2D6, CYP2C19, and CYP2C9; 2 non-CYP enzymes, NAT1 and TMPT; and 2 transporter genes, SLCO1B1 and SLCO2B1, are presented herein according to ethnic classification.
Collapse
Affiliation(s)
- Michael Man
- Discovery and Development Statistics, Eli Lilly and Company, Lilly Corporate Center DC 2026, Indianapolis, IN 46285, USA.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Bonary ARK, Jouyban A, Tamizi E, Mehr SE, Samini M. Effect of memantine on plasma concentrations of carbamazepine and phenytoin in rats: A controlled experimental study. Curr Ther Res Clin Exp 2009; 70:359-65. [PMID: 24683244 DOI: 10.1016/j.curtheres.2009.10.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/01/2009] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Elderly patients, especially those with Alzheimer's disease, may be prescribed memantine and an antiepileptic drug concurrently. OBJECTIVE The aim of this study was to compare the interaction of memantine with phenobarbital (an enzyme inducer) and chloramphenicol (an enzyme inhibitor) on plasma concentrations of carbamazepine (CBZ), CBZ-10,11-epoxide (CBZE), and phenytoin in an experimental model. METHODS Eight groups of rats (200-230 g) were treated for 14 days each. In groups 1 and 2, phenobarbital 50 mg/kg was administered daily as an enzyme inducer 60 minutes before CBZ 50 mg/kg or phenytoin 30 mg/kg administration, respectively. In groups 3 and 4, chloramphenicol 300 mg/kg was administered daily as an enzyme inhibitor 60 minutes before CBZ or phenytoin administration, respectively. In groups 5 and 6, memantine 20 mg/kg was administered daily 60 minutes before CBZ or phenytoin, respectively. In group 7, CBZ alone was administered daily; in group 8, phenytoin alone was administered daily. Two hours after the last intragastric gavage, animals were anesthetized with ether and 2 mL of blood was drawn from the heart into a syringe containing EDTA. A validated method developed in this study was used for simultaneous determination of CBZ, CBZE, and phenytoin concentrations in rat plasma. RESULTS The study comprised 8 groups of 9 male adult Wistar rats each. Compared with groups 7 and 8, concurrent use of CBZ or phenytoin with phenobarbital (groups 1 and 2) was associated with significantly lower mean (SEM) plasma concentrations of CBZ (3.45 [0.16] vs 2.20 [0.21] μg/mL; P < 0.001) and phenytoin (3.68 [0.09] vs 1.63 [0.15] μg/mL; P < 0.001) and a significantly higher plasma CBZE concentration (9.85 [0.29] vs 11.18 [0.29] μg/mL; P < 0.05). Concurrent use of CBZ or phenytoin with chloramphenicol (groups 3 and 4) was associated with significantly higher plasma concentrations of CBZ (4.81 [0.17] μg/mL; P < 0.001) and phenytoin (6.24 [0.22] μg/mL; P < 0.001) and a significantly lower plasma CBZE concentration (3.88 [0.25] μg/mL; P < 0.001). Concurrent use of CBZ or phenytoin with memantine (groups 5 and 6) was not associated with a significant change in the plasma concentration of CBZ, CBZE, or phenytoin. CONCLUSION Memantine was not associated with a significant change in the plasma concentration of CBZ, CBZE, or phenytoin in this experimental model.
Collapse
Affiliation(s)
- Amir Reza Karami Bonary
- Faculty of Specialized Veterinary Science, Islamic Azad University, Science & Research Branch, Tehran, Iran
| | - Abolghasem Jouyban
- Pharmacy and Drug Applied Research Center, Tabriz University (Medical Sciences), Tabriz, Iran
| | - Elnaz Tamizi
- Biotechnology Research Center, Tabriz University (Medical Sciences), Tabriz, Iran
| | | | - Morteza Samini
- Faculty of Specialized Veterinary Science, Islamic Azad University, Science & Research Branch, Tehran, Iran ; Tehran University of Medical Sciences, Tehran, Iran
| |
Collapse
|
21
|
Inhibition of voriconazole metabolism by chloramphenicol in an adolescent with central nervous system aspergillosis. Antimicrob Agents Chemother 2008; 52:4172-4. [PMID: 18794387 DOI: 10.1128/aac.00805-08] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
For an adolescent with bacterial meningitis and subsequent cerebral aspergillosis, intravenous voriconazole dose requirements substantially decreased during coadministration with intravenous chloramphenicol and considerably rose after discontinuation of the antibiotic. In agreement with in vitro evidence, these data suggest that chloramphenicol is a rather significant inhibitor of hepatic CYP3A4 and/or CYP2C19.
Collapse
|
22
|
Lee MD, Ayanoglu E, Gong L. Drug-induced changes in P450 enzyme expression at the gene expression level: a new dimension to the analysis of drug-drug interactions. Xenobiotica 2007; 36:1013-80. [PMID: 17118918 DOI: 10.1080/00498250600861785] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Drug-drug interactions (DDIs) caused by direct chemical inhibition of key drug-metabolizing cytochrome P450 enzymes by a co-administered drug have been well documented and well understood. However, many other well-documented DDIs cannot be so readily explained. Recent investigations into drug and other xenobiotic-mediated expression changes of P450 genes have broadened our understanding of drug metabolism and DDI. In order to gain additional information on DDI, we have integrated existing information on drugs that are substrates, inhibitors, or inducers of important drug-metabolizing P450s with new data on drug-mediated expression changes of the same set of cytochrome P450s from a large-scale microarray gene expression database of drug-treated rat tissues. Existing information on substrates and inhibitors has been updated and reorganized into drug-cytochrome P450 matrices in order to facilitate comparative analysis of new information on inducers and suppressors. When examined at the gene expression level, a total of 119 currently marketed drugs from 265 examined were found to be cytochrome P450 inducers, and 83 were found to be suppressors. The value of this new information is illustrated with a more detailed examination of the DDI between PPARalpha agonists and HMG-CoA reductase inhibitors. This paper proposes that the well-documented, but poorly understood, increase in incidence of rhabdomyolysis when a PPARalpha agonist is co-administered with a HMG-CoA reductase inhibitor is at least in part the result of PPARalpha-induced general suppression of drug metabolism enzymes in liver. The authors believe this type of information will provide insights to other poorly understood DDI questions and stimulate further laboratory and clinical investigations on xenobiotic-mediated induction and suppression of drug metabolism.
Collapse
Affiliation(s)
- M D Lee
- Iconix Biosciences, Mountain View, CA 94043, USA.
| | | | | |
Collapse
|
23
|
Abstract
Drug-drug interactions in the field of infectious diseases continue to expand as new drugs are approved, metabolic enzymes and transporters are identified, and recommendations for co-administration of drugs are revised. This article provides an overview of the principles and mechanisms of drug-drug interactions and describes pharmacokinetic-pharmacodynamic interactions commonly associated with antibacterial therapy, antiviral agents (non-retroviral), and drugs for tuberculosis.
Collapse
Affiliation(s)
- Manjunath P Pai
- University of New Mexico, College of Pharmacy, MSC09 5360, Albuquerque, NM 87131, USA
| | | | | |
Collapse
|
24
|
Abstract
[reaction: see text] Azinomycins have potential therapeutic value as antitumor agents; however, their biosynthesis is poorly understood. Here, we provide the first demonstration of a protein cell-free system capable of supporting complete in vitro biosynthesis of the antitumor agent azinomycin B. The cell-free system is utilized to probe the cofactor dependence and substrate requirements of the pathway en route to azinomycin.
Collapse
Affiliation(s)
- Chaomin Liu
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA
| | | | | |
Collapse
|
25
|
Kim KA, Chung J, Jung DH, Park JY. Identification of cytochrome P450 isoforms involved in the metabolism of loperamide in human liver microsomes. Eur J Clin Pharmacol 2004; 60:575-81. [PMID: 15365656 DOI: 10.1007/s00228-004-0815-3] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2004] [Accepted: 07/12/2004] [Indexed: 10/26/2022]
Abstract
OBJECTIVE The purpose of the present study was to elucidate the cytochrome P450 (P450) isoform(s) involved in the metabolism of loperamide (LOP) to N-demethylated LOP (DLOP) in human liver microsomes. METHODS Three established approaches were used to identify the P450 isoforms responsible for LOP N-demethylation using human liver microsomes and cDNA-expressed P450 isoforms: (1) correlation of LOP N-demethylation activity with marker P450 activities in a panel of human liver microsomes, (2) inhibition of enzyme activity by P450-selective inhibitors, and (3) measurement of DLOP formation by cDNA-expressed P450 isoforms. The relative contribution of P450 isoforms involved in LOP N-demethylation in human liver microsomes were estimated by applying relative activity factor (RAF) values. RESULTS The formation rate of DLOP showed biphasic kinetics, suggesting the involvement of multiple P450 isoforms. Apparent Km and Vmax values were 21.1 microM and 122.3 pmol/min per milligram of protein for the high-affinity component and 83.9 microM and 412.0 pmol/min per milligram of protein for the low-affinity component, respectively. Of the cDNA-expressed P450 s tested, CYP2B6, CYP2C8, CYP2D6, and CYP3A4 catalyzed LOP N-demethylation. LOP N-demethylation was significantly inhibited when coincubated with quercetin (a CYP2C8 inhibitor) and ketoconazole (a CYP3A4 inhibitor) by 40 and 90%, respectively, but other chemical inhibitors tested showed weak or no significant inhibition. DLOP formation was highly correlated with CYP3A4-catalyzed midazolam 1-hydroxylation (rs=0.829; P<0.01), CYP2B6-catalzyed 7-ethoxy-4-trifluoromethylcoumarin O-deethylation (rs=0.691; P<0.05), and CYP2C8-catalyzed paclitaxel 6alpha-hydroxylation (rs=0.797; P<0.05). CONCLUSION CYP2B6, CYP2C8, CYP2D6, and CYP3A4 catalyze LOP N-demethylation in human liver microsomes, and among them, CYP2C8 and CYP3A4 may play a crucial role in LOP metabolism at the therapeutic concentrations of LOP. Coadministration of these P450 inhibitors may cause drug interactions with LOP. However, the clinical significance of potential interaction of LOP metabolism by CYP2C8 and CYP3A4 inhibitors should be studied further.
Collapse
Affiliation(s)
- Kyoung-Ah Kim
- Department of Pharmacology, Gil Medical Center, Gachon Medical School, 1198 Kuwol-dong, 405-760, Incheon, Namdong-gu, Korea
| | | | | | | |
Collapse
|