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https://www.readbyqxmd.com/read/28425104/inactivation-kinetics-and-residual-activity-of-cyp3a4-after-treatment-with-erythromycin
#1
Yuko Ishikawa, Takeshi Akiyoshi, Ayuko Imaoka, Hisakazu Ohtani
This study aimed to characterize the inactivation kinetics of cytochrome P450 3A4 (CYP3A4) by erythromycin, which involves mechanism-based inhibition (MBI), in detail. In addition to an MBI assay based on the conventional method in which erythromycin and recombinant CYP3A4 were pre-incubated for 15 min, we also evaluated the long-term MBI kinetics of this reaction by pre-incubating for 120 min. MBI profiles were obtained using three typical substrates, testosterone, midazolam, and nifedipine. In the long-term assay, erythromycin evoked a time-dependent biphasic reduction in enzyme activity, but some residual activity (α) was detected in the terminal phase...
April 20, 2017: Biopharmaceutics & Drug Disposition
https://www.readbyqxmd.com/read/28410117/racial-disparities-disruptive-genes-in-prostate-carcinogenesis
#2
Savita Singh, Alexis Plaga, Girish C Shukla
Population specific studies in prostate cancer (PCa) reveal a unique heterogeneous etiology. Various factors, such as genetics, environment and dietary regimen seems to determine disease progression, therapeutic resistance and rate of mortality. Enormous disparity documented in disease incidences, aggressiveness and mortality in PCa among AAs (African Americans) and CAs (Caucasian Americans) is attributed to the variations in genetics, epigenetics and their association with metabolism. Scientific and clinical evidences have revealed the influence of variations in Androgen Receptor (AR), RNAse L, macrophage scavenger receptor 1 (MRS1), androgen metabolism by cytochrome P450 3A4, differential regulation of microRNAs, epigenetic alterations and diet in racial disparity in PCa incidences and mortality...
June 1, 2017: Frontiers in Bioscience (Scholar Edition)
https://www.readbyqxmd.com/read/28407303/rifampicin-reverses-nicardipine-effect-inducing-uncontrolled-essential-hypertension
#3
Elena-Mihaela Cordeanu, Sébastien Gaertner, Alix Faller, Corina Mirea, Jean-Marc Lessinger, Veronique Kemmel, Dominique Stephan
Dihydropyridine calcium-channel blockers are a known substrate for the cytochrome P450 isoform 3A4. Rifampicin, an antitubercular agent, is one of the most potent inducers of hepatic and intestinal CYP3A4 thus increasing dihydropyridine metabolism. We report a case of a 67-year-old hypertensive female treated with a 4-drug antihypertensive regimen including a dihydropyridine (nicardipine 50mg bid), who was admitted for septic arthritis of the knee requiring antibiotic treatment with teicoplanin 400mg od and rifampicin 600mg bid...
April 13, 2017: Fundamental & Clinical Pharmacology
https://www.readbyqxmd.com/read/28393714/gender-difference-of-hepatic-and-intestinal-cyp3a4-in-cyp3a-humanized-mice-generated-by-a-human-chromosome-engineering-technique
#4
Kaoru Kobayashi, Chihiro Abe, Mika Endo, Yasuhiro Kazuki, Mitsuo Oshimura, Kan Chiba
BACKGROUND: Cytochrome P450 3A4 (CYP3A4) is an important drug-metabolizing enzyme that is expressed in the liver and small intestine of humans. Various factors influence the expression of CYP3A4, but gender difference in CYP3A4 expression remains debatable. OBJECTIVE: To clarify gender difference of hepatic and intestinal CYP3A4 in CYP3A-humanized mice generated by a human artificial chromosome (HAC) vector system. The CYP3A-humanized (CYP3A-HAC) mice have essential regulatory regions, including promoters and enhancers, and unknown elements affecting the expression of CYP3A4...
April 4, 2017: Drug Metabolism Letters
https://www.readbyqxmd.com/read/28393710/rolapitant-a-nk-1-receptor-antagonist-for-the-prevention-of-chemotherapy-induced-nausea-and-vomiting
#5
Bernardo Leon Rapaport
BACKGROUND: Nausea and vomiting are among the most feared side effects of chemotherapy and can prevent cancer patients from completing their treatment regimens. Rolapitant is a highly selective neurokinin-1 (NK-1) receptor antagonist with very good oral activity, central nervous system penetration and a long (180-hour) plasma half-life. Unlike other available NK-1 receptor antagonists, rolapitant does not inhibit or induce cytochrome P450 (CYP) 3A4. METHODS: Findings from recent phase II and III clinical trials of rolapitant in patients receiving highly or moderately emetogenic chemotherapy are reviewed and discussed...
April 6, 2017: Reviews on Recent Clinical Trials
https://www.readbyqxmd.com/read/28385095/in-vitro-inhibitory-effects-of-pristimerin-on-human-liver-cytochrome-p450-enzymes
#6
Xiaoyi Hao, Jianlei Yuan, Yansen Xu, Zhao Wang, Jianzhang Hou, Tao Hu
1. Pristimerin (PTM) is a biological component isolated from Chinese herbal plant Celastrus and Maytenus spp and it possesses numerous pharmacological activities. However, whether PTM affects the activity of human liver cytochrome P450 (CYP) enzymes remains unclear. 2. In this study, the inhibitory effects of PTM on the eight human liver CYP isoforms (i.e., 1A2, 3A4, 2A6, 2E1, 2D6, 2C9, 2C19, and 2C8) were investigated in vitro using human liver microsomes (HLMs). 3. The results showed that PTM inhibited the activity of CYP1A2, 3A4, and 2C9, with IC50 values of 21...
April 7, 2017: Xenobiotica; the Fate of Foreign Compounds in Biological Systems
https://www.readbyqxmd.com/read/28383355/influence-of-cyp2c8-polymorphisms-on-imatinib-steady-state-trough-level-in-chronic-myeloid-leukemia-and-gastrointestinal-stromal-tumor-patients
#7
Michiel C Verboom, Loes Visser, Sander Kouwen, Jesse J Swen, Jeroen Diepstraten, Ward F Posthuma, Hans Gelderblom, Daniëlle van Lammeren, Erik B Wilms
Imatinib trough levels have been associated with its clinical effects. During chronic use of imatinib, CYP2C8 becomes an important metabolizing enzyme because of cytochrome P450 3A4 (CYP3A4) autoinhibition. Single nucleotide polymorphisms (SNPs) in CYP2C8 may affect imatinib trough levels. This study investigates the effect of common CYP2C8 polymorphisms [*1B (rs7909236), *1C (rs17110453), *3 (rs11572080 and rs10509681), and *4 (rs1058930)] on steady-state trough levels imatinib during chronic imatinib use in 43 patients with chronic myeloid leukemia or gastrointestinal stromal tumors...
April 5, 2017: Pharmacogenetics and Genomics
https://www.readbyqxmd.com/read/28377716/human-cytochrome-p450-3a4-as-a-biocatalyst-effects-of-the-engineered-linker-in-modulation-of-coupling-efficiency-in-3a4-bmr-chimeras
#8
Danilo Degregorio, Serena D'Avino, Silvia Castrignanò, Giovanna Di Nardo, Sheila J Sadeghi, Gianluca Catucci, Gianfranco Gilardi
Human liver cytochrome P450 3A4 is the main enzyme involved in drug metabolism. This makes it an attractive target for biocatalytic applications, such as the synthesis of pharmaceuticals and drug metabolites. However, its poor solubility, stability and low coupling have limited its application in the biotechnological context. We previously demonstrated that the solubility of P450 3A4 can be increased by creating fusion proteins between the reductase from Bacillus megaterium BM3 (BMR) and the N-terminally modified P450 3A4 (3A4-BMR)...
2017: Frontiers in Pharmacology
https://www.readbyqxmd.com/read/28355970/clinical-impact-and-management-of-fluconazole-discontinuation-on-sirolimus-levels-in-bone-marrow-transplant-patients
#9
Edith Nwaroh, Jennifer Jupp, Esther Jadusingh, Gregory Guilcher
Sirolimus, an immunosuppressant, is indicated post-allogeneic stem cell transplant to reduce the risk of graft-versus-host-disease. Sirolimus is metabolized by cytochrome P450 3A4 and is a substrate of the P-glycoprotein (P-gp) drug efflux pump. Interactions with known inhibitors of the CYP3A4 enzyme and P-glycoprotein, such as fluconazole, are anticipated. Co-administration of fluconazole leads to an increase in sirolimus blood concentrations due to an inhibition of metabolism. The discontinuation of fluconazole will likely result in a decline in sirolimus blood concentrations, leaving patients at risk of graft-versus-host-disease...
January 1, 2017: Journal of Oncology Pharmacy Practice
https://www.readbyqxmd.com/read/28350999/discovery-of-novel-1-2-3-4-tetrahydrobenzo-4-5-thieno-2-3-c-pyridine-derivatives-as-potent-and-selective-cyp17-inhibitors
#10
Mingliang Wang, Yanjia Fang, Shoulai Gu, Fangfang Chen, Zhengjiang Zhu, Xun Sun, Jidong Zhu
The inhibition of CYP17 to block androgen biosynthesis is a well validated strategy for the treatment of prostate cancer. Herein we reported the design, synthesis and structure-activity relationship (SAR) study for a series of novel 1,2,3,4- tetrahydrobenzo[4,5]thieno[2,3-c]pyridine derivatives. Some analogs demonstrated a potent inhibition to both rat and human CYP17 protein and reduced testosterone production in human H295R cell line. Some analogs also showed high selectivity against other CYP enzymes such as 3A4, 1A2, 2C9, 2C19 and 2D6, which may limit side effects due to drug-drug interactions...
March 21, 2017: European Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28346810/an-automated-multiplexed-hepatotoxicity-and-cyp-induction-assay-using-heparg-cells-in-2d-and-3d
#11
Lindsey M Ott, Karthik Ramachandran, Lisa Stehno-Bittel
Drug-induced liver injury (DILI) and drug-drug interactions (DDIs) are concerns when developing safe and efficacious compounds. We have developed an automated multiplex assay to detect hepatotoxicity (i.e., ATP depletion) and metabolism (i.e., cytochrome P450 1A [CYP1A] and cytochrome P450 3A4 [CYP3A4] enzyme activity) in two-dimensional (2D) and three-dimensional (3D) cell cultures. HepaRG cells were cultured in our proprietary micromold plates and produced spheroids. HepaRG cells, in 2D or 3D, expressed liver-specific proteins throughout the culture period, although 3D cultures consistently exhibited higher albumin secretion and CYP1A/CYP3A4 enzyme activity than 2D cultures...
March 1, 2017: SLAS Discovery
https://www.readbyqxmd.com/read/28345929/utility-of-cyp3a4-and-pxr-car-cyp3a4-3a7-transgenic-mouse-models-to-assess-the-magnitude-of-cyp3a4-mediated-drug-drug-interactions
#12
Justin Q Ly, Kirsten Messick, Ann Qin, Ryan H Takahashi, Edna F Choo
Species differences in the expression, activity, regulation, and substrate specificity of metabolizing enzymes preclude the use of animal models to predict clinical drug-drug interactions (DDIs). The objective of this work is to determine if the transgenic (Tg) Cyp3a(-/-)Tg-3A4Hep/Int and Nr1i2/Nr1i3(-/-)-Cyp3a(-/-)Tg-PXR-CAR-3A4/3A7Hep/Int (PXR-CAR-CYP3A4/3A7) mouse models could be used to predict in vivo DDI of 10 drugs; alprazolam, bosutinib, crizotinib, dasatinib, gefitinib, ibrutinib, regorafenib, sorafenib, triazolam, and vandetinib (as victims); with varying magnitudes of reported CYP3A4 clinical DDI...
April 7, 2017: Molecular Pharmaceutics
https://www.readbyqxmd.com/read/28344076/inhibition-of-human-cyp3a4-and-cyp3a5-enzymes-by-gomisin-c-and-gomisin-g-two-lignan-analogs-derived-from-schisandra-chinensis
#13
Jin Zhao, Tao Sun, Jing-Jing Wu, Yun-Feng Cao, Zhong-Ze Fang, Hong-Zhi Sun, Zhi-Tu Zhu, Kun Yang, Yong-Zhe Liu, Frank J Gonzalez, Jun Yin
Gomisin C (GC) and gomisin G (GG) are two lignan analogs isolated from the Traditional Chinese Medicine Schisandra chinensis which possesses multiple pharmacological activities. However, the potential herb-drug interactions (HDI) between these lignans and other drugs through inhibiting human cytochrome P450 3A4 (CYP3A4) and CYP3A5 remains unclear. In the present study, the inhibitory action of GC and GG on CYP3A4 and CYP3A5 were investigated. The results demonstrated that both GC and GG strongly inhibited CYP3A-mediated midazolam 1'-hydroxylation, nifedipine oxidation and testosterone 6β-hydroxylation...
March 24, 2017: Fitoterapia
https://www.readbyqxmd.com/read/28343293/pharmacokinetic-and-pharmacodynamic-considerations-in-the-treatment-of-chronic-lymphocytic-leukemia-ibrutinib-idelalisib-and-venetoclax
#14
REVIEW
Madeline Waldron, Allison Winter, Brian T Hill
Management of chronic lymphocytic leukemia has changed markedly over the last several years with the emergence of several novel oral agents targeting B-cell receptor and Bcl-2 signaling pathways. For patients requiring treatment, ibrutinib, idelalisib, and venetoclax offer unique clinical benefits with a different set of therapeutic considerations compared with traditional parenteral therapy. Despite the conveniences afforded by oral therapy, these agents also carry unique logistical obstacles. Drug interactions with agents that are metabolized via the cytochrome P450 3A4 pathway are possible with all three agents...
March 25, 2017: Clinical Pharmacokinetics
https://www.readbyqxmd.com/read/28343093/influence-of-genetic-variants-of-cyp2d6-cyp2c9-cyp2c19-and-cyp3a4-on-antiepileptic-drug-metabolism-in-pediatric-patients-with-refractory-epilepsy
#15
Miguel A López-García, Iris A Feria-Romero, Héctor Serrano, Darío Rayo-Mares, Pietro Fagiolino, Marta Vázquez, Consuelo Escamilla-Núñez, Israel Grijalva, David Escalante-Santiago, Sandra Orozco-Suarez
BACKGROUND: Identified the polymorphisms of CYP2D6, CYP2C9, CYP2C19 and CYP3A4, within a rigorously selected population of pediatric patients with drug-resistant epilepsy. METHOD: The genomic DNA of 23 drug-resistant epilepsy patients and 7 patients with good responses were analyzed. Ten exons in these four genes were genotyped, and the drug concentrations in saliva and plasma were determined. RESULTS: The relevant SNPs with pharmacogenomics relations were CYP2D6*2 (rs16947) decreased your activity and CYP2D6*4 (rs1065852), CYP2C19*2 (rs4244285) and CYP3A4*1B (rs2740574) by association with poor metabolizer...
January 19, 2017: Pharmacological Reports: PR
https://www.readbyqxmd.com/read/28339191/allosteric-activation-of-cytochrome-p450-3a4-via-progesterone-bioconjugation
#16
Vanja Polic, Karine Auclair
Human cytochrome P450 3A4 (CYP3A4) is responsible for the metabolism of the majority of drugs. As such, it is implicated in many adverse drug-drug and food-drug interactions, and is of significant interest to the pharmaceutical industry. This enzyme is known to simultaneously bind multiple ligands and display atypical enzyme kinetics, suggestive of allostery and cooperativity. As well, evidence of a postulated peripheral allosteric binding site has provoked debate around its significance and location. We report the use of bioconjugation to study the significance of substrate binding at the proposed allosteric site and its effect on CYP3A4 activity...
March 29, 2017: Bioconjugate Chemistry
https://www.readbyqxmd.com/read/28329820/hepatocellular-toxicity-of-imidazole-and-triazole-antimycotic-agents
#17
Patrizia Haegler, Lorenz Joerin, Stephan Krähenbühl, Jamal Bouitbir
Hepatotoxicity has been described for all antimycotic azoles currently marketed. A possible mechanism involving mitochondrial dysfunction has been postulated for ketoconazole, but not for the other azoles. The aim of the current investigations was to study the toxicity of different azoles in human cell models and to find out mechanisms of their toxicity. In HepG2 cells, posaconazole and ketoconazole were cytotoxic starting at 20 and 50 µM and decreased the cellular ATP content starting at 5 and 10 µM, respectively...
January 27, 2017: Toxicological Sciences: An Official Journal of the Society of Toxicology
https://www.readbyqxmd.com/read/28327932/integrated-safety-analysis-of-rolapitant-with-coadministered-drugs-from-phase-ii-iii-trials-an-assessment-of-cyp2d6-or-bcrp-inhibition-by-rolapitant
#18
S Barbour, T Smit, X Wang, D Powers, S Arora, V Kansra, M Aapro, J Herrstedt
Background: Rolapitant, a long-acting neurokinin (NK) 1 receptor antagonist (RA), has demonstrated efficacy in prevention of chemotherapy-induced nausea and vomiting in patients administered moderately or highly emetogenic chemotherapy. Unlike other NK 1 RAs, rolapitant does not inhibit or induce cytochrome P450 (CYP) 3A4, but it does inhibit CYP2D6 and breast cancer resistance protein (BCRP). To analyze potential drug-drug interactions between rolapitant and concomitant medications, this integrated safety analysis of four double-blind, randomized phase II or III studies of rolapitant examined adverse events by use versus non-use of drug substrates of CYP2D6 or BCRP...
February 23, 2017: Annals of Oncology: Official Journal of the European Society for Medical Oncology
https://www.readbyqxmd.com/read/28301431/cyp3a4-activity-is-markedly-lower-in-patients-with-crohn-s-disease
#19
Aze Wilson, Rommel G Tirona, Richard B Kim
BACKGROUND: Disease-dependent changes in the activity of drug metabolizing enzymes and transporters, such as Cytochrome P450 (CYP) 3A4 and P-glycoprotein (P-gp), are thought to have a major influence on the disposition of shared substrates. However, little is known regarding the in vivo relevance of these 2 proteins during drug therapy for gastrointestinal diseases. Our aim was to elucidate the activity of CYP3A4 and P-gp in subjects with Crohn's disease (CD) and to evaluate their influence on budesonide pharmacokinetics...
May 2017: Inflammatory Bowel Diseases
https://www.readbyqxmd.com/read/28293270/effect-of-moringa-oleifera-lam-leaf-powder-on-the-pharmacokinetics-of-nevirapine-in-hiv-infected-adults-a-one-sequence-cross-over-study
#20
Tsitsi G Monera-Penduka, Charles C Maponga, Alan R Wolfe, Lubbe Wiesner, Gene D Morse, Charles F B Nhachi
BACKGROUND: Moringa oleifera Lam., an herb commonly consumed by HIV-infected people on antiretroviral therapy, inhibits cytochrome P450 3A4, 1A2 and 2D6 activity in vitro; and may alter the pharmacokinetics (PK) of antiretroviral drugs metabolized via the same pathways. However, in vitro drug interaction activity may not translate to a clinically significant effect. Therefore, the effect of moringa leaf powder on the PK of nevirapine in HIV-infected people was investigated. METHODS: Adult patients at steady-state dosing with nevirapine were admitted for 12-h intensive PK sampling following a 21-day herbal medicine washout...
2017: AIDS Research and Therapy
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