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https://www.readbyqxmd.com/read/29232137/inhibition-of-human-cyp3a4-by-rationally-designed-ritonavir-like-compounds-impact-and-interplay-of-the-side-group-functionalities
#1
Eric R Samuels, Irina Sevrioukova
Structure-function relationships of nine rationally designed ritonavir-like compounds were investigated to better understand the ligand binding and inhibitory mechanism in human drug-metabolizing cytochrome P450 3A4 (CYP3A4). The analogs had a similar backbone and pyridine and tert-butyloxycarbonyl (Boc) as the heme-ligating and terminal groups, respectively. N-Isopropyl, N-cyclopentyl, or N-phenyl were the R1-side group substituents alone (compounds 5a-c) or in combination with phenyl or indole at the R2 position (8a-c and 8d-f subseries, respectively)...
December 12, 2017: Molecular Pharmaceutics
https://www.readbyqxmd.com/read/29226313/model-based-assessments-of-cyp-mediated-drug-drug-interaction-risk-of-alectinib-physiologically-based-pharmacokinetic-modeling-supported-clinical-development
#2
Yumi Cleary, Michael Gertz, Peter N Morcos, Li Yu, Kuresh Youdim, Alex Phipps, Stephen Fowler, Neil Parrott
Alectinib is a selective anaplastic lymphoma kinase (ALK) inhibitor approved for the treatment of ALK-positive non-small cell lung cancer. Alectinib and its major active metabolite M4 exhibited drug-drug interaction (DDI) potential through cytochrome P450 (CYP) enzymes CYP3A4 and CYP2C8 in vitro. Clinical relevance of the DDI risk was investigated as part of a rapid development program to fulfil the breakthrough therapy designation. Therefore, a strategy with a combination of physiologically based pharmacokinetic (PBPK) modeling and limited clinical trials focused on generating informative data for modeling was taken to ensure extrapolation ability of DDI risk...
December 11, 2017: Clinical Pharmacology and Therapeutics
https://www.readbyqxmd.com/read/29223619/differential-effects-of-hepatic-cirrhosis-on-the-intrinsic-clearances-of-sorafenib-and-imatinib-by-cyps-in-human-liver
#3
Michael Murray, Tina B Gillani, Sussan Ghassabian, Robert J Edwards, Tristan Rawling
The tyrosine kinase inhibitors sorafenib and imatinib are important in the treatment of a range of cancers but adverse effects in some patients necessitate dosage modifications. CYP3A4 has a major role in the oxidation of sorafenib to its N-oxide and N-hydroxymethyl metabolites and also acts in concert with CYP2C8 to mediate imatinib N-demethylation. CYP3A4 expression and function are impaired in patients with advanced liver disease, whereas the functions of CYP2C enzymes are relatively preserved. We evaluated the biotransformation of sorafenib and imatinib in well-characterized microsomal fractions from 17 control subjects and 19 individuals with hepatic cirrhosis of varying severity...
December 6, 2017: European Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/29191071/allosteric-activation-of-cytochrome-p450-3a4-by-efavirenz-facilitates-midazolam-binding
#4
Tomohiko Ichikawa, Hirofumi Tsujino, Takahiro Miki, Masaya Kobayashi, Chiaki Matsubara, Sara Miyata, Taku Yamashita, Kohei Takeshita, Yasushige Yonezawa, Tadayuki Uno
1. The purpose of this study is to investigate the heteroactivation mechanism of CYP3A4 by efavirenz, which enhances metabolism of midazolam in vivo, in terms of its binding to CYP3A4 with in vitro spectroscopic methods. 2. Efavirenz exhibited a type II spectral change with binding to CYP3A4 indicating a possible inhibitor. Although dissociation constant (Kd) was approximated as 550 μM, efavirenz enhanced binding affinity of midazolam as a co-existing drug with an estimated iKd value of 5.6 µM which is comparable to a clinical concentration...
December 1, 2017: Xenobiotica; the Fate of Foreign Compounds in Biological Systems
https://www.readbyqxmd.com/read/29183231/in-silico-prediction-of-multiple-category-classification-model-for-cytochrome-p450-inhibitors-and-non-inhibitors-using-machine-learning-method
#5
J H Lee, S Basith, M Cui, B Kim, S Choi
The cytochrome P450 (CYP) enzyme superfamily is involved in phase I metabolism which chemically modifies a variety of substrates via oxidative reactions to make them more water-soluble and easier to eliminate. Inhibition of these enzymes leads to undesirable effects, including toxic drug accumulations and adverse drug-drug interactions. Hence, it is necessary to develop in silico models that can predict the inhibition potential of compounds for different CYP isoforms. This study focused on five major CYP isoforms, including CYP1A2, 2C9, 2C19, 2D6 and 3A4, that are responsible for more than 90% of the metabolism of clinical drugs...
October 2017: SAR and QSAR in Environmental Research
https://www.readbyqxmd.com/read/29176019/in-vitro-modulation-of-the-cytochrome-p450-and-abcb1-p-glycoprotein-activities-of-the-aqueous-extract-of-allophylus-cominia-l-sw-leaves
#6
Carlos L Pérez, Maria T Donato, Ivones Hernández, Miriam T Paz Lopes, Evangelina Marrero, Jose A Herrera, Maria J Gómez-Lechón, Idania Rodeiro
BACKGROUND: The aqueous extract of the Allophylus cominia (L) Sw (Sapindaceae) leaves has shown anti-diabetic, anti-obesity and anti-inflammatory properties. In the Caribbean region, it is typically used for the treatment of type-2 diabetes. METHODS: Considering the herb-drug interaction, the aim of this study was to evaluate the potential effects of the A. cominia extract on the cytochrome P450 (CYP) (rat hepatocyte model) and P-glycoprotein (P-gp) (4T1 cell line) systems...
November 25, 2017: Drug Metabolism and Personalized Therapy
https://www.readbyqxmd.com/read/29168799/modulation-of-cytochrome-p450-p-glycoprotein-and-pregnane-x-receptor-by-selected-antimalarial-herbs-implication-for-herb-drug-interaction
#7
Pius S Fasinu, Vamshi K Manda, Olivia R Dale, Nosa O Egiebor, Larry A Walker, Shabana I Khan
Seven medicinal plants popularly used for treating malaria in West Africa were selected to assess herb-drug interaction potential through a series of in vitro methods. Fluorescent cytochrome P450 (CYP) assays were conducted using the recombinant CYP enzymes for CYP1A2, CYP2A6, CYP2B6, CYP2C9, CYP2C19, CYP2D6 and CYP3A4 to assess the effect of the methanolic extracts on the metabolic activity of CYPs. Secondly, the inhibitory effect of the extracts was evaluated on P-glycoproteins (P-gp) using calcein-AM, a fluorescent substrate, in MDCK-II and hMDR1-MDCK-II cells...
November 23, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/29160300/genome-wide-association-study-identifies-the-common-variants-in-cyp3a4-and-cyp3a5-responsible-for-variation-in-tacrolimus-trough-concentration-in-caucasian-kidney-transplant-recipients
#8
W S Oetting, B Wu, D P Schladt, W Guan, R P Remmel, R B Mannon, A J Matas, A K Israni, P A Jacobson
The immunosuppressant tacrolimus (TAC) is metabolized by both cytochrome P450 3A4 (CYP3A4) and CYP3A5 enzymes. It is common for European Americans (EA) to carry two CYP3A5 loss-of-function (LoF) variants that profoundly reduces TAC metabolism. Despite having two LoF alleles, there is still considerable variability in TAC troughs and identifying additional variants in genes outside of the CYP3A5 gene could provide insight into this variability. We analyzed TAC trough concentrations in 1345 adult EA recipients with two CYP3A5 LoF alleles in a genome-wide association study...
November 21, 2017: Pharmacogenomics Journal
https://www.readbyqxmd.com/read/29155491/variation-in-the-response-of-clozapine-biotransformation-pathways-in-human-hepatic-microsomes-to-cyp1a2-and-cyp3a4-selective-inhibitors
#9
Michael Murray, Wei V Zhang, Robert J Edwards
The atypical antipsychotic agent clozapine (CLZ) is effective in many patients who are resistant to conventional antipsychotic drugs. Cytochromes P450 (CYPs) 1A2 and 3A4 oxidise CLZ to norCLZ and CLZ N-oxide in human liver. Concurrent treatment with inducers and inhibitors of CYP1A2 modulates CLZ elimination that disrupts therapy. Drug-drug interactions involving CYP3A4 are also significant but less predictable. To further characterise the factors underlying these interactions, we used samples from a cohort of human livers to assess variation in CLZ oxidation pathways in relation to intrinsic CYP3A4 and CYP1A2 activities and the effects of the corresponding selective inhibitors ketoconazole (0...
November 20, 2017: Basic & Clinical Pharmacology & Toxicology
https://www.readbyqxmd.com/read/29145924/pharmacokinetic-interaction-between-bedaquiline-and-clofazimine-in-patients-with-drug-resistant-tuberculosis
#10
G Maartens, M J E Brill, M Pandie, E M Svensson
<h2>BACKGROUND:</h2>Bedaquiline (BDQ) and clofazimine (CFZ) are both recommended for treating drug-resistant tuberculosis (DR-TB). As CFZ is an inhibitor of the cytochrome P450 isoenzyme 3A4 (CYP3A4) in vitro, and BDQ a substrate of CYP3A4, there is a potential for pharmacokinetic (PK) drug-drug interaction that may result in increased BDQ exposure when co-administered with CFZ, which could increase the toxicity of BDQ.<h2>METHODS:</h2>We assessed the effect of co-administered CFZ on BDQ bioavailability, or on clearance of BDQ and its N-monodesmethyl metabolite (M2), in patients with DR-TB using a population PK model developed from data of patients with DR-TB...
November 16, 2017: International Journal of Tuberculosis and Lung Disease
https://www.readbyqxmd.com/read/29139224/a-polyelectrolyte-multilayer-platform-for-investigating-growth-factor-delivery-modes-in-human-liver-cultures
#11
Christine Lin, Raimundo Romero, Lioudmila V Sorokina, Kimberly R Ballinger, Laura W Place, Matt J Kipper, Salman R Khetani
Polyelectrolyte multilayers (PEMs) of chitosan and heparin are useful for mimicking growth factor (GF) binding to extracellular matrix (ECM) as in vivo. Here, we developed a PEM platform for delivering bound/adsorbed GFs to monocultures of primary human hepatocytes (PHHs) and PHH/non-parenchymal cell (NPC) co-cultures, which are useful for drug development and regenerative medicine. The effects of ECM protein coating (collagen I, fibronectin, and Matrigel®) and terminal PEM layer on PHH attachment/functions were determined...
November 15, 2017: Journal of Biomedical Materials Research. Part A
https://www.readbyqxmd.com/read/29136681/assessment-of-multiple-cytochrome-p450-activities-in-metabolically-inactivated-human-liver-microsomes-and-roles-of-p450-2c-isoforms-in-reaction-phenotyping-studies
#12
Norie Murayama, Kanako Yajima, Mikiko Hikawa, Kanami Shimura, Yu Ishii, Masaki Takada, Yasuhiro Uno, Masahiro Utoh, Kazuhide Iwasaki, Hiroshi Yamazaki
The fraction of substrate metabolized (fm ) can be used to estimate drug interactions and can be determined by comparison of the intrinsic clearances (CLint ) of victim drugs obtained from inhibited and uninhibited hepatic enzymes. Commercially available human liver microsomes were recently developed in which one cytochrome P450 (P450) isoform is selectively inactivated. These inactivated liver microsomes were used to evaluate the roles of P450 2C isoforms in the depletion and oxidation of probe substrates...
November 14, 2017: Biopharmaceutics & Drug Disposition
https://www.readbyqxmd.com/read/29133569/efficacy-of-tilorone-dihydrochloride-against-ebola-virus-infection
#13
Sean Ekins, Mary A Lingerfelt, Jason E Comer, Alexander N Freiberg, Jon C Mirsalis, Kathleen O'Loughlin, Anush Harutyunyan, Claire McFarlane, Carol E Green, Peter B Madrid
Tilorone dihydrochloride (tilorone) is a small-molecule, orally bioavailable drug that is used clinically as an antiviral outside of the US. A machine learning model trained on anti-Ebola virus (EBOV) screening data previously identified tilorone as a potent in vitro EBOV inhibitor, making it a candidate for the treatment of Ebola virus disease (EVD). In the present study, a series of in vitro ADMET (absorption, distribution, metabolism, excretion, toxicity) assays demonstrated the drug has excellent solubility, high Caco-2 permeability, was not a P-glycoprotein substrate and had no inhibitory activity against five human CYP450 enzymes (3A4, 2D6, 2C19, 2C9 and 1A2)...
November 13, 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/29121650/flavin-containing-monooxygenase-3-fmo3-role-in-busulphan-metabolic-pathway
#14
Ibrahim El-Serafi, Ylva Terelius, Manuchehr Abedi-Valugerdi, Seán Naughton, Maryam Saghafian, Ali Moshfegh, Jonas Mattsson, Zuzana Potácová, Moustapha Hassan
Busulphan (Bu) is an alkylating agent used in the conditioning regimen prior to hematopoietic stem cell transplantation (HSCT). Bu is extensively metabolized in the liver via conjugations with glutathione to form the intermediate metabolite (sulfonium ion) which subsequently is degraded to tetrahydrothiophene (THT). THT was reported to be oxidized forming THT-1-oxide that is further oxidized to sulfolane and finally 3-hydroxysulfolane. However, the underlying mechanisms for the formation of these metabolites remain poorly understood...
2017: PloS One
https://www.readbyqxmd.com/read/29120380/in-vitro-phase-i-metabolism-of-crv431-a-novel-oral-drug-candidate-for-chronic-hepatitis-b
#15
Daniel J Trepanier, Daren R Ure, Robert T Foster
The cytochrome P450-mediated Phase I in vitro metabolism of CRV431 was studied using selective chemical inhibition and recombinant human enzymes. Additionally, the metabolic profile of CRV431 in human, rat, and monkey liver microsomes was investigated. Liver microsomes were incubated for 0-80 min with CRV431, and the metabolite profile was assessed by electrospray ionization liquid chromatography mass spectrometry (ESI-LCMS). CRV431 was extensively metabolized through oxidation to produce various hydroxylated and demethylated species...
November 9, 2017: Pharmaceutics
https://www.readbyqxmd.com/read/29117990/simultaneous-physiologically-based-pharmacokinetic-pbpk-modeling-of-parent-and-active-metabolites-to-investigate-complex-cyp3a4-drug-drug-interaction-potential-a-case-example-of-midostaurin
#16
Helen Gu, Catherine Dutreix, Sam Rebello, Taoufik Ouatas, Lai Wang, Dung Yu Chun, Heidi J Einolf, Handan He
Midostaurin (PKC412) is being investigated for the treatment of acute myeloid leukemia (AML) and advanced systemic mastocytosis (advSM). It is extensively metabolized by cytochrome P450 (CYP) 3A4 to form 2 major active metabolites, CGP52421 and CGP62221. In vitro and clinical drug-drug interaction (DDI) studies indicated that midostaurin and its metabolites are substrates, reversible and time-dependent inhibitors, and inducers of CYP3A4. A simultaneous pharmacokinetic model of parent and active metabolites was initially developed by incorporating data from in vitro, preclinical, and clinical pharmacokinetic studies in healthy volunteers and in patients with AML or advSM...
November 8, 2017: Drug Metabolism and Disposition: the Biological Fate of Chemicals
https://www.readbyqxmd.com/read/29117640/functional-characterization-of-22-cyp3a4-protein-variants-to-metabolize-ibrutinib-in-vitro
#17
Ren-Ai Xu, Jian Wen, Pengfei Tang, Chenchen Wang, Saili Xie, Bo-Wen Zhang, Quan Zhou, Jian-Ping Cai, Guo-Xin Hu
Cytochrome P450 3A4 (CYP3A4) is quantitatively the most important P450 enzyme in adults. It is suggested that CYP3A4 genetic polymorphisms may influence the rate of the metabolism and elimination of CYP3A4 substrates in humans. Ibrutinib is an anti-cancer drug and primarily metabolized by CYP3A4. The aim of this study was to systematically investigate the effects of 22 CYP3A4 protein variants on the metabolism of ibrutinib in vitro. When compared with wild-type CYP3A4.1, two variants (CYP3A4.17 and CYP3A4.24) had no detectable enzyme activity; five variants (CYP3A4...
November 8, 2017: Basic & Clinical Pharmacology & Toxicology
https://www.readbyqxmd.com/read/29109577/creation-of-a-natural-health-products-database-for-assessing-safety-for-patients-with-chronic-kidney-disease-or-renal-transplant
#18
Sharon Leung, Karen Shalansky, Puneet Vashisht, Marianna Leung, Judith G Marin
Introduction: There is a lack of published safety information on the use of natural health products (NHPs) for patients with chronic kidney disease (CKD) or renal transplant. Objective: To create an online database to provide evidence-based safety recommendations for commonly used NHPs, specific to patients with CKD or renal transplant. Methods: NHPs used by CKD and transplant patients in British Columbia were identified from the records of the BC Provincial Renal Agency...
September 2017: Canadian Journal of Hospital Pharmacy
https://www.readbyqxmd.com/read/29108449/iatrogenic-cushing-syndrome-in-a-47-year-old-hiv-positive-woman-on-ritonavir-and-inhaled-budesonide
#19
Lily Colpitts, Thomas B Murray, Sami G Tahhan, Jody P Boggs
Iatrogenic Cushing syndrome (CS) is a well-known complication of treating patients with systemic steroids. More rarely, it has been described in HIV-positive patients on ritonavir (RTV) while using the inhaled corticosteroid fluticasone, which is metabolized through the cytochrome P450 3A4 (CYP3A4) enzyme system. In the presence of RTV, a known CYP3A4 enzyme inhibitor, the interaction can result in impaired metabolism and systemic accumulation of inhaled fluticasone resulting in iatrogenic CS. Iatrogenic CS has been less often described with inhaled budesonide compared to inhaled fluticasone...
January 1, 2017: Journal of the International Association of Providers of AIDS Care
https://www.readbyqxmd.com/read/29104319/cytochrome-b5-plays-a-dual-role-in-the-reaction-cycle-of-cytochrome-p450-3a4-during-oxidation-of-the-anticancer-drug-ellipticine
#20
Marie Stiborová, Radek Indra, Eva Frei, Kateřina Kopečková, Heinz H Schmeiser, Tomáš Eckschlager, Vojtěch Adam, Zbyněk Heger, Volker M Arlt, Václav Martínek
Abstract: Ellipticine is an anticancer agent that forms covalent DNA adducts after enzymatic activation by cytochrome P450 (CYP) enzymes, mainly by CYP3A4. This process is one of the most important ellipticine DNA-damaging mechanisms for its antitumor action. Here, we investigated the efficiencies of human hepatic microsomes and human recombinant CYP3A4 expressed with its reductase, NADPH:CYP oxidoreductase (POR), NADH:cytochrome b5 reductase and/or cytochrome b5 in Supersomes™ to oxidize this drug...
2017: Monatshefte Für Chemie
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