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https://www.readbyqxmd.com/read/28211700/from-genotype-to-phenotype-cytochrome-p450-2d6-mediated-drug-clearance-in-humans
#1
Jie Gao, Xin Tian, Jun Zhou, Ming-Zhu Cui, Hai-Feng Zhang, Na Gao, Qiang Wen, Hai-Ling Qiao
How genotypic variation results in phenotypic differences is still a challenge for biology. In the field of drug metabolism the means by which specific cytochrome P4502D6 (CYP2D6) genotypes yield different phenotypes at various levels (molecular, cellular, and organismal) is an important question, as differences in CYP2D6 activity can contribute to adverse drug reactions. Herein, the genotype of CYP2D6 was determined along with the absolute content of CYP2D6 and microsomal protein per gram of liver in human liver microsomes, the molecular, cellular (microsomal, tissue, organ), and organismal phenotype of CYP2D6 determined; the effect of genotype on each phenotype of CYP2D6-mediated dextromethorphan clearance (CL) was delineated, and the overall genotype-phenotype relationship for CYP2D6 was charted...
February 17, 2017: Molecular Pharmaceutics
https://www.readbyqxmd.com/read/28196829/marmoset-cytochrome-p450-3a4-expressed-in-liver-and-small-intestine-tissues-efficiently-metabolizes-midazolam-alprazolam-nifedipine-and-testosterone
#2
Shotaro Uehara, Yasuhiro Uno, Kazuyuki Nakanishi, Sakura Ishii, Takashi Inoue, Erika Sasaki, Hiroshi Yamazaki
Common marmosets (Callithrix jacchus), small New World primates, are increasingly attracting attention as potentially useful animal models for drug development. However, characterization of cytochrome P450 (P450) 3A enzymes involved in the metabolism of a wide variety of drugs has remained in marmosets. In this study, sequence homology, tissue distribution, and enzymatic property of marmoset P450 3A4 orthologue, 3A5 orthologue, and 3A90 were investigated. Marmoset P450 3A forms exhibited high amino acid sequence identities (88-90%) to the human and cynomolgus monkey P450 3A orthologues and evolutionary closeness to human and cynomolgus monkey P450 3A orthologues, compared with other P450 3A enzymes...
February 14, 2017: Drug Metabolism and Disposition: the Biological Fate of Chemicals
https://www.readbyqxmd.com/read/28153841/cholic-acid-feeding-leads-to-increased-cyp2d6-expression-in-cyp2d6-humanized-mice
#3
Xian Pan, Rebecca Kent, Kyoung-Jae Won, Hyunyoung Jeong
Cytochrome P450 2D6 (CYP2D6) is a major drug-metabolizing enzyme, but factors governing transcriptional regulation of its expression remain poorly understood. Based on previous reports of small heterodimer partner (SHP) playing an important role as a transcriptional repressor of CYP2D6 expression, here we investigated how a known upstream regulator of SHP expression, namely cholestasis triggered by cholic acid (CA) feeding in mice, can lead to altered CYP2D6 expression. To this end, CYP2D6-humanized (Tg-CYP2D6) mice were fed with CA-supplemented or control diet for 14 days, and hepatic expression of multiple genes was examined...
February 2, 2017: Drug Metabolism and Disposition: the Biological Fate of Chemicals
https://www.readbyqxmd.com/read/28119166/in-vitro-toxicological-evaluation-of-ncs-382-a-high-affinity-antagonist-of-%C3%AE-hydroxybutyrate-ghb-binding
#4
K R Vogel, G R Ainslie, J-B Roullet, A McConnell, K M Gibson
γ-Hydroxybutyric acid (GHB), a minor metabolite of the inhibitory neurotransmitter GABA, can accumulate to significant concentrations in the heritable disorder of GABA degradation, succinic semialdehyde dehydrogenase (SSADH) deficiency (SSADHD). Moreover, GHB may be employed in therapeutic settings (treatment of narcolepsy), as well as instances of illicit activity, including acquaintance sexual assault and the induction of euphoria. High-affinity binding sites for GHB in the brain have been identified, although the absolute identity of these receptors remains unclear...
January 22, 2017: Toxicology in Vitro: An International Journal Published in Association with BIBRA
https://www.readbyqxmd.com/read/28087463/effect-of-22-cyp2d6-variants-found-in-the-chinese-population-on-tolterodine-metabolism-in%C3%A2-vitro
#5
Hao Wang, Da-Peng Dai, Peng Sun, Li-Ping Xu, Bing-Qing Liang, Jian-Ping Cai, Guo-Xin Hu
Cytochrome P450 2D6 (CYP2D6) is an important member of the cytochrome P450 enzyme superfamily. We recently identified 22 novel variants in the Chinese population using PCR and bidirectional sequencing methods. The aim of this study is to characterize the enzymatic activity of these variants and their effects on the metabolism of the antimuscarinic drug tolterodine in vitro. A baculovirus-mediated expression system was used to express wild-type CYP2D6 and 24 variants (CYP2D6*2, CYP2D6*10, and 22 novel CYP2D6 variants) at high levels...
February 25, 2017: Chemico-biological Interactions
https://www.readbyqxmd.com/read/28074989/-antidepressants-agents-in-breast-cancer-patients-using-tamoxifen-review-of-basic-and-clinical-evidence
#6
María Elisa Irarrázaval O, Leonardo Gaete G
Tamoxifen (Tmf), is a standard of care for women with estrogen receptor positive (ER+) breast cancer. Endoxifen is a Tmf metabolite generated by cytochrome P450 2D6 (CYP2D6). Antidepressive agents (AD) are often prescribed to women with breast cancer not only for depression, but also for anxiety and hot flashes. Some AD are substrates or inhibitors of the Tmf metabolic pathway. Therefore there may be interactions when Tmf and AD are prescribed simultaneously. Oncologic protection afforded by Tmf may become less effective or null when AD are indicated, especially in poor metabolizing patients...
October 2016: Revista Médica de Chile
https://www.readbyqxmd.com/read/28073119/in-vitro-inhibition-of-human-cyp450s-1a2-2c9-3a4-5-2d6-and-2e1-by-grandisin
#7
Maísa Daniela Habenschus, Fernanda de Lima Moreira, Norberto Peporine Lopes, Anderson R M de Oliveira
Grandisin, a lignan isolated from many species of plants, such as Virola surinamensis, is a potential drug candidate due to its biological properties, highlighted by its antitumor and trypanocidal activities. In this study, the inhibitory effects of grandisin on the activities of human cytochrome P450 enzymes were investigated by using human liver microsomes. Results showed that grandisin is a competitive inhibitor of CYP2C9 and a competitive and mechanism-based inhibitor of CYP3A4/5. The apparent Ki value for CYP2C9 was 50...
January 10, 2017: Planta Medica
https://www.readbyqxmd.com/read/28058783/characterization-of-phase-i-and-phase-ii-hepatic-metabolism-and-reactive-intermediates-of-larrea-nitida-cav-and-its-lignan-compounds
#8
Hyesoo Jeong, Soolin Kim, Jimin Lee, Jin Young Park, Wenmei Zhou, Xiyuan Liu, So Dam Kim, Yun Seon Song, Chang-Young Jang, Sei-Ryang Oh, Sangho Choi, Minsun Chang
Larrea nitida Cav. (LNC), which belongs to the family Zygophyllaceae, is widely indigenous and used in South America to treat various pathological conditions. It contains the antioxidant and antiinflammatory but toxic nordihydroguaiaretic acid (NDGA) as well as O-methylated metabolite of NDGA (MNDGA) as bioactive compounds. The hepatic metabolism-based toxicological potential of extracts of LNC (LNE), NDGA, and MNDGA has not previously been reported. The present study aimed to characterize the phase I and phase II hepatic metabolism and reactive intermediates of LNE, NDGA, and MNDGA and their effects on the major drug-metabolizing enzymes in vitro and ex vivo...
January 2017: Phytotherapy Research: PTR
https://www.readbyqxmd.com/read/28056947/triptolide-induces-hepatotoxicity-via-inhibition-of-cyp450s-in-rat-liver-microsomes
#9
Yan Lu, Tong Xie, Yajie Zhang, Fuqiong Zhou, Jie Ruan, Weina Zhu, Huaxu Zhu, Zhe Feng, Xueping Zhou
BACKGROUND: Triptolide (TP), an active constituent of Tripterygium wilfordii, possesses numerous pharmacological activities. However, its effects on cytochrome P450 enzymes (CYP450s) in rats remain unexplored. METHODS: In this study, the effects of triptolide on the six main CYP450 isoforms (1A2, 2C9, 2C19, 2D6, 2E1, and 3A) were investigated both in vivo and in vitro. We monitored the body weight, survival proportions, liver index, changes in pathology, and biochemical index upon TP administration, in vivo...
January 5, 2017: BMC Complementary and Alternative Medicine
https://www.readbyqxmd.com/read/27997172/aminomethyl-derived-beta-secretase-bace1-inhibitors-engaging-gly230-without-an-anilide-functionality
#10
Christopher R Butler, Kevin Ogilvie, Luis Martinez-Alsina, Gabriela Barreiro, Elizabeth M Beck, Charles E Nolan, Kevin Atchison, Eric Benvenuti, Leanne Buzon, Shawn Doran, Cathleen Gonzales, Christopher J Helal, Xinjun Hou, Mei-Hui Hsu, Eric F Johnson, Kimberly Lapham, Lorraine Lanyon, Kevin Parris, Brian T O'Neill, David Riddell, Ashley Robshaw, Felix Vajdos, Michael A Brodney
A growing subset of β-secretase (BACE1) inhibitors for the treatment of Alzheimer's disease (AD) utilizes an anilide chemotype that engages a key residue (Gly230) in the BACE1 binding site. Although the anilide moiety affords excellent potency, it simultaneously introduces a third hydrogen bond donor that limits brain availability and provides a potential metabolic site leading to the formation of an aniline, a structural motif of prospective safety concern. We report herein an alternative aminomethyl linker that delivers similar potency and improved brain penetration relative to the amide moiety...
December 20, 2016: Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/27988492/cytochrome-p-450-2d6-cyp2d6-genotype-and-breast-cancer-recurrence-in-tamoxifen-treated-patients-evaluating-the-importance-of-loss-of-heterozygosity
#11
Thomas P Ahern, Daniel L Hertz, Per Damkier, Bent Ejlertsen, Stephen J Hamilton-Dutoit, James M Rae, Meredith M Regan, Alastair M Thompson, Timothy L Lash, Deirdre P Cronin-Fenton
Tamoxifen therapy for estrogen receptor-positive breast cancer reduces the risk of recurrence by approximately one-half. Cytochrome P-450 2D6, encoded by the polymorphic cytochrome P-450 2D6 gene (CYP2D6), oxidizes tamoxifen to its most active metabolites. Steady-state concentrations of endoxifen (4-hydroxy-N-desmethyltamoxifen), the most potent antiestrogenic metabolite, are reduced in women whose CYP2D6 genotypes confer poor enzyme function. Thirty-one studies of the association of CYP2D6 genotype with breast cancer survival have yielded heterogeneous results...
January 15, 2017: American Journal of Epidemiology
https://www.readbyqxmd.com/read/27978469/highly-sensitive-lc-ms-ms-methods-for-the-determination-of-seven-human-cyp450-activities-using-small-oral-doses-of-probe-drugs-in-human
#12
Alexia Grangeon, Sophie Gravel, Fleur Gaudette, Jacques Turgeon, Veronique Michaud
Cocktails composed of several Cytochrome P450 (CYP450)-selective probe drugs have been shown of value to characterize in vivo drug-metabolism activities. Our objective was to develop and validate highly sensitive and selective LC-MS/MS assays allowing the determination of seven major human CYP450 isoenzyme activities following administration of low oral doses of a modified CYP450 probe-drug cocktail in patients. The seven-drug cocktail was composed of caffeine, bupropion, tolbutamide, omeprazole, dextromethorphan, midazolam (all administered concomitantly) and chlorzoxazone (administered separately) to phenotype for CYP1A2, 2B6, 2C9, 2C19, 2D6, 3A4/5 and 2E1, respectively...
January 1, 2017: Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences
https://www.readbyqxmd.com/read/27974250/the-influence-of-genetic-predisposition-and-autoimmune-hepatitis-inducing-antigens-in-disease-development
#13
Matthias Hardtke-Wolenski, Janine Dywicki, Katja Fischer, Martin Hapke, Maren Sievers, Jerome Schlue, Mark S Anderson, Richard Taubert, Fatih Noyan, Michael P Manns, Elmar Jäckel
: Autoimmune hepatitis (AIH) is defined as a chronic liver inflammation with loss of tolerance against hepatocytes. The etiology and pathophysiology of AIH are still poorly understood because reliable animal models are limited. Therefore, we recently introduced a model of experimental murine AIH by a self-limited adenoviral infection with the AIH type 2 antigen formiminotransferase cyclodeaminase (FTCD). We could demonstrate that break of humoral tolerance towards liver specific autoantigens like FTCD and cytochrome P450 2D6 (CYP2D6) is not dependent on the genetic background...
December 11, 2016: Journal of Autoimmunity
https://www.readbyqxmd.com/read/27932669/quantification-of-the-steady-state-plasma-concentrations-of-clozapine-and-n-desmethylclozapine-in-japanese-patients-with-schizophrenia-using-a-novel-hplc-method-and-the-effects-of-cyps-and-abc-transporters-polymorphisms
#14
Yumiko Akamine, Yuka Sugawara-Kikuchi, Tsukasa Uno, Tetsuo Shimizu, Masatomo Miura
Background This study developed a novel high-performance liquid chromatography (HPLC) method for the simultaneous quantification of clozapine and its active metabolite, N-desmethylclozapine, in human plasma and investigated the effects of various factors, including genetic polymorphisms in cytochrome P450 (CYP) 2D6, CYP3A5, ABCB1 and ABCG2, on the steady-state plasma trough concentrations (C0) of clozapine and N-desmethylclozapine in Japanese patients with schizophrenia. Methods Forty-five patients had been receiving fixed doses of clozapine for at least four weeks...
January 1, 2017: Annals of Clinical Biochemistry
https://www.readbyqxmd.com/read/27923405/cytochrome-p450-2d-mediated-metabolism-is-not-necessary-for-tafenoquine-and-primaquine-to-eradicate-the-erythrocytic-stages-of-plasmodium-berghei
#15
Erin E Milner, Jonathan Berman, Diana Caridha, Samuel P Dickson, Mark Hickman, Patricia J Lee, Sean R Marcsisin, Lisa T Read, Norma Roncal, Brian A Vesely, Lisa H Xie, Jing Zhang, Ping Zhang, Qigui Li
BACKGROUND: Due to the ability of the 8-aminoquinolines (8AQs) to kill different stages of the malaria parasite, primaquine (PQ) and tafenoquine (TQ) are vital for causal prophylaxis and the eradication of erythrocytic Plasmodium sp. parasites. Recognizing the potential role of cytochrome (CYP) 450 2D6 in the metabolism and subsequent hepatic efficacy of 8-aminoquinolines, studies were designed to explore whether CYP2D-mediated metabolism was related to the ability of single-dose PQ and TQ to eliminate the asexual and sexual erythrocytic stages of Plasmodium berghei...
December 7, 2016: Malaria Journal
https://www.readbyqxmd.com/read/27918912/predicting-cyp2d6-phenotype-from-resting-brain-perfusion-images-by-gradient-boosting
#16
Giulio Napolitano, Julia C Stingl, Matthias Schmid, Roberto Viviani
The cytochrome P450 enzyme 2D6 is involved in the metabolism of 20% of all commonly used drugs, including many psychotropic drugs and CNS-active substances. CYP2D6 is among the CYP enzymes with the highest expression levels in the brain, suggesting a role in the local brain metabolism of psychotropic drugs and the existence of endogenous substrates. The genetic polymorphism of CYP2D6, which causes individual differences in activity levels of the enzyme, has also been characterized functionally in human brain imaging studies...
January 30, 2017: Psychiatry Research
https://www.readbyqxmd.com/read/27917125/comparison-of-liver-cell-models-using-the-basel-phenotyping-cocktail
#17
Benjamin Berger, Massimiliano Donzelli, Swarna Maseneni, Franziska Boess, Adrian Roth, Stephan Krähenbühl, Manuel Haschke
Currently used hepatocyte cell systems for in vitro assessment of drug metabolism include hepatoma cell lines and primary human hepatocyte (PHH) cultures. We investigated the suitability of the validated in vivo Basel phenotyping cocktail (caffeine [CYP1A2], efavirenz [CYP2B6], losartan [CYP2C9], omeprazole [CYP2C19], metoprolol [CYP2D6], midazolam [CYP3A4]) in vitro and characterized four hepatocyte cell systems (HepG2 cells, HepaRG cells, and primary cryopreserved human hepatocytes in 2-dimensional [2D] culture or in 3D-spheroid co-culture) regarding basal metabolism and CYP inducibility...
2016: Frontiers in Pharmacology
https://www.readbyqxmd.com/read/27882219/cyp2d6-gene-polymorphisms-in-brazilian-patients-with-breast-cancer-treated-with-adjuvant-tamoxifen-and-its-association-with-disease-recurrence
#18
Mariella De Ameida Melo, Rodrigo José De Vasconcelos-Valença, Fidelis Manes Neto, Rafael Soares Borges, Danylo Rafhael Costa-Silva, Maria Da Conceição Barros-Oliveira, Umbelina Soares Borges, Airlane Pereira Alencar, Vladimir Costa Silva, Benedito Borges Da Silva
At present, there is controversy regarding the efficacy of tamoxifen in breast cancer patients who are carriers of cytochrome P450 2D6 (CYP2D6) gene polymorphisms, in terms of recurrence and overall survival. Thus, the aim of the present study was to investigate the association of the CYP2D6 *4, *10 and *17 gene polymorphisms with breast cancer recurrence in a Brazilian population. The cohort comprised 40 receptor-positive breast cancer patients without recurrence and 40 with distant recurrence. A 3-ml sample of peripheral blood was collected from each patient to determine the presence of the *4, *10 and *17 single nucleotide polymorphisms of the CYP2D6 gene by quantitative polymerase chain reaction analysis...
November 2016: Biomedical Reports
https://www.readbyqxmd.com/read/27875319/enhanced-oral-bioavailability-of-metoprolol-with-gallic-acid-and-ellagic-acid-in-male-wistar-rats-involvement-of-cyp2d6-inhibition
#19
Bhargavi Latha Athukuri, Prasad Neerati
BACKGROUND: Cytochrome P450-2D6 (CYP2D6), a member of the CYP450 mixed function oxidase system, is an important CYP isoform with regard to herbal-drug interactions and is responsible for the metabolism of nearly 25% of drugs. Until now, studies on the effects of various phytochemicals on CYP2D6 activity in vivo have been very rare. Gallic acid and ellagic acid are natural polyphenols which are widely distributed in fruits and medicinal plants. In the present study, the effects of gallic acid and ellagic acid pretreatment on intestinal transport and oral bioavailability of metoprolol were investigated...
December 1, 2016: Drug Metabolism and Personalized Therapy
https://www.readbyqxmd.com/read/27853934/evaluation-of-in-vitro-cytochrome-p450-inhibition-and-in-vitro-fate-of-structurally-diverse-n-oxide-metabolites-case-studies-with-clozapine-levofloxacin-roflumilast-voriconazole-and-zopiclone
#20
Poonam Giri, Sneha Naidu, Nirmal Patel, Harilal Patel, Nuggehally R Srinivas
BACKGROUND AND OBJECTIVES: The role of metabolite(s) to elicit potential clinical drug-drug interaction (DDI) via cytochrome P450 enzymes (CYP) is gaining momentum. In this context, the role of N-oxides for in vitro CYP inhibition has not been evaluated. The objectives of this study were: (a) to examine in vitro CYP inhibition of N-oxides of clozapine, levofloxacin, roflumilast, voriconazole and zopiclone in a tiered approach and (b) evaluate in vitro fate of aforementioned N-oxides examined in recombinant CYPs, human microsomes and hepatocytes...
November 16, 2016: European Journal of Drug Metabolism and Pharmacokinetics
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