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https://www.readbyqxmd.com/read/28089686/simulations-of-cytochrome-p450-3a4-mediated-drug-drug-interactions-by-simple-two-compartment-model-assisted-static-method
#1
Katsumi Iga, Akiko Kiriyama
In order to predict cytochrome P450 3A4 (CYP3A4)-mediated drug-drug interactions (DDIs), a simple two-compartment model assisted, overall inhibition-activity (Ai, overall) method was derived based upon two concepts. One concept was that the increase in blood victim-level and fold increase in the area under the blood victim-level curve (AUCR) produced by DDI are determined entirely by Ai, overall, the hepatic availability of the victim and fraction of urinary excreted unchanged victim, where Ai, overall is determined by the perpetrator-specific CYP isoform inhibition activities (Ai,CYPs, DDI predictor-1) and victim-specific fractional CYP isoform contributions (fm,CYPs, predictor-2)...
January 12, 2017: Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/28088572/bcs-class-iv-drugs-highly-notorious-candidates-for-formulation-development
#2
REVIEW
Rohan Ghadi, Neha Dand
BCS class IV drugs (e.g., amphotericin B, furosemide, acetazolamide, ritonavir, paclitaxel) exhibit many characteristics that are problematic for effective oral and per oral delivery. Some of the problems associated include low aqueous solubility, poor permeability, erratic and poor absorption, inter and intra subject variability and significant positive food effect which leads to low and variable bioavailability. Also, most of the class IV drugs are substrate for P-glycoprotein (low permeability) and substrate for CYP3A4 (extensive pre systemic metabolism) which further potentiates the problem of poor therapeutic potential of these drugs...
January 11, 2017: Journal of Controlled Release: Official Journal of the Controlled Release Society
https://www.readbyqxmd.com/read/28087064/effect-of-cyp2d6-polymorphisms-on-the-pharmacokinetics-of-propafenone-and-its-two-main-metabolites
#3
Mohammad-Reza Rouini, Minoo Afshar
AIM OF THE STUDY: Propafenone (PPF) is an antiarrhythmic drug, metabolized mainly by CYP2D6 to 5-hydroxypropafenone (5OH-PPF) and by CYP3A4 to norpropafenone (NOR-PPF). CYP2D6 shows a high degree of genetic polymorphism which is associated with diminished antiarrhythmic efficacy or cardiac seizures/cardiotoxicity. This study aimed to investigate the effect of the CYP2D6 polymorphism on the pharmacokinetics of PPF and its two main metabolites. The usefulness of PPF/5OH-PPF ratio for CYP2D6 phenotyping in healthy adults was also evaluated...
December 19, 2016: Thérapie
https://www.readbyqxmd.com/read/28079798/clinical-and-genetic-factors-associated-with-warfarin-maintenance-dose-in-northern-chinese-patients-with-mechanical-heart-valve-replacement
#4
Rui Liu, Jian Cao, Qian Zhang, Xin-Miao Shi, Xiao-Dong Pan, Ran Dong
The effects of genetic variants on warfarin dosing vary among different ethnic groups, especially in the Chinese population. The objective of this study was to recruit patients through a rigorous experimental design and to perform a comprehensive screen to identify gene polymorphisms that may influence warfarin dosing in northern Han Chinese patients with mechanical heart valve replacement. Consenting patients (n = 183) with a stable warfarin dose were included in this study. Ninety-six single nucleotide polymorphisms (SNPs) in 30 genes involved in warfarin pharmacological pathways were genotyped using the Illumina SNP GoldenGate Assay, and their associations with warfarin dosing were assessed using univariate regression analysis with post hoc comparison using least significant difference analysis...
January 2017: Medicine (Baltimore)
https://www.readbyqxmd.com/read/28078726/dissecting-the-cytochrome-p450-1a2-and-3a4-mediated-metabolism-of-aflatoxin-b1-in-ligand-and-protein-contributions
#5
Lars Olsen, Flemming S Jørgensen, Silvia Bonomo
Aflatoxin B1 (AFB1) is a chemically intriguing compound because it has several potential sites of metabolism (SOMs) while only some of them are observed experimentally. Cytochrome P450 (CYP) 3A4 and 1A2 are the major isoforms involved in its metabolism. Here, we systematically investigate reactivity and accessibility of all possible SOMs in these two CYPs to elucidate AFB1 metabolism. Density functional theory (DFT) calculations were used to determine activation energies for each possible reaction. Aliphatic hydroxylation on position 9A and 3α are energetically favored, whereas position 9 is the preferred site for epoxidation...
January 12, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28074333/rosiglitazone-metabolism-in-human-liver-microsomes-using-a-substrate-depletion-method
#6
Maryam Bazargan, David J R Foster, Andrew K Davey, Beverly S Muhlhausler
BACKGROUND: Elimination of rosiglitazone in humans is via hepatic metabolism. The existing studies suggest that CYP2C8 is the major enzyme responsible, with a minor contribution from CYP2C9; however, other studies suggest the involvement of additional cytochrome P450 enzymes and metabolic pathways. Thus a full picture of rosiglitazone metabolism is unclear. OBJECTIVE: This study aimed to improve the current understanding of potential drug-drug interactions and implications for therapy by evaluating the kinetics of rosiglitazone metabolism and examining the impact of specific inhibitors on its metabolism using the substrate depletion method...
January 10, 2017: Drugs in R&D
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/28069789/hypotension-induced-by-the-concomitant-use-of-a-calcium-channel-blocker-and-clarithromycin
#8
Sayako Takeuchi, Yuki Kotani, Toshihide Tsujimoto
In the elderly, calcium-channel blockers are the first-line treatment for hypertension, and macrolides are commonly prescribed antibiotics. Here we report a 78-year-old man taking nifedipine, diltiazem and carvedilol who presented with persistent hypotension and bradycardia after clarithromycin was prescribed. He was diagnosed with drug-induced hypotension and treated with fluid resuscitation and vasoactive agents. His symptoms gradually improved. He was transferred out of the intensive care unit 3 days after hospitalisation...
January 9, 2017: BMJ Case Reports
https://www.readbyqxmd.com/read/28067999/evaluation-of-pharmacokinetic-interactions-between-lesinurad-a-new-selective-urate-reabsorption-inhibitor-and-cyp-enzyme-substrates-sildenafil-amlodipine-tolbutamide-and-repaglinide
#9
Michael Gillen, Chun Yang, David Wilson, Shakti Valdez, Caroline Lee, Bradley Kerr, Zancong Shen
Lesinurad is a selective uric acid reabsorption inhibitor approved for the treatment of hyperuricemia associated with gout in combination with xanthine oxidase inhibitors. In vitro assays indicate that lesinurad is an inducer of CYPs in the order CYP3A > CYP2C8 > CYP2C9 > CYP2C19 > CYP2B6 and an inhibitor of CYP2C8 and CYP2C9. To investigate the drug interaction potential of lesinurad, clinical drug interaction studies were conducted. Open-label studies in volunteers investigated the effects of single-/multiple-dose lesinurad on the pharmacokinetics of sildenafil and amlodipine (CYP3A4 induction), tolbutamide (CYP2C9 inhibition/induction), and repaglinide (CYP2C8 inhibition/induction)...
January 9, 2017: Clinical Pharmacology in Drug Development
https://www.readbyqxmd.com/read/28067989/tacrolimus-interaction-with-nafcillin-resulting-in-significant-decreases-in-tacrolimus-concentrations-a-case-report
#10
Minkey Wungwattana, Marizela Savic
Tacrolimus (TAC) is subject to many drug interactions as a result of its metabolism primarily via CYP450 isoenzyme 3A4. Numerous case reports of TAC and CYP3A4 inducers and inhibitors have been described including antimicrobials, calcium channel antagonists, and antiepileptic drugs. We present the case of a 13-year-old patient with cystic fibrosis and a history of liver transplantation, where subtherapeutic TAC concentrations were suspected to be a result of concomitant TAC and nafcillin (NAF) therapy. The observed drug interaction occurred on two separate hospital admissions, during both of which the patient exhibited therapeutic TAC concentrations prior to exposure to NAF, a CYP3A4 inducer...
January 9, 2017: Transplant Infectious Disease: An Official Journal of the Transplantation Society
https://www.readbyqxmd.com/read/28063163/immediate-versus-modified-release-hydrocortisone-in-mitotane-treated-patients-with-adrenocortical-cancer
#11
Marianne Weigel, Stefanie Hahner, Mark Sherlock, Amar Agha, Lucy Ann Behan, Paul M Stewart, Wiebke Arlt, Daniela Beier, Kathrin Frey, Kathrin Zopf, Marcus Quinkler
OBJECTIVE: Mitotane induces hepatic CYP3A4 activity, resulting in accelerated cortisol inactivation, and also increases cortisol binding globulin (CBG). Therefore, higher hydrocortisone doses are required in patients with adrenocortical cancer (ACC) on mitotane treatment. Modified release hydrocortisone has not been used in mitotane-treated ACC patients yet. AIM: Case series to compare serum cortisol, calculated free serum cortisol and ACTH levels in ACC patients on mitotane treatment with immediate and modified release hydrocortisone...
January 7, 2017: Clinical Endocrinology
https://www.readbyqxmd.com/read/28062541/evaluation-of-a-novel-renewable-hepatic-cell-model-for-prediction-of-clinical-cyp3a4-induction-using-a-correlation-based-ris-approach
#12
Rongjun Zuo, Feng Li, Sweta Parikh, Li Cao, Kirsten L Cooper, Yulong Hong, Jin Liu, Ronald A Faris, Daochuan Li, Hongbing Wang
Metabolism enzyme induction-mediated drug-drug interactions need to be carefully characterized in vitro for drug candidates in order to predict in vivo outcomes of safety risk and therapeutic efficiency. Currently, both the FDA and EMA recommend using primary human hepatocytes as the "Gold Standard" in vitro test system for studying the induction potential of candidate drugs on cytochrome P450 (CYP), CYP3A4, CYP1A2, and CYP2B6. However, primary human hepatocytes are known to bear inherent limitations such as limited supply and large lot-to-lot variations which result in an experimental burden to qualify new lots...
January 6, 2017: Drug Metabolism and Disposition: the Biological Fate of Chemicals
https://www.readbyqxmd.com/read/28060049/ritonavir-and-topical-ocular-corticosteroid-induced-cushing-s-syndrome-in-an-adolescent-with-hiv-1-infection
#13
Paul G Rainsbury, Jessica Sharp, Alison Tappin, Martin Hussey, Alexandra Lenko, Caroline Foster
Cushing's syndrome following topical ocular corticosteroid use is extremely rare. We describe a case of symptomatic Cushing's syndrome in an adolescent male with sight-threatening vernal keratoconjunctivitis on antiretroviral therapy for HIV-1 infection that included ritonavir, a potent cytochrome p450 CYP3A4 inhibitor. CYP3A4 inhibition reduces the metabolism of exogenous corticosteroids leading to suppression of endogenous steroid production and Cushing's syndrome.
January 3, 2017: Pediatric Infectious Disease Journal
https://www.readbyqxmd.com/read/28053220/application-of-static-modeling-in-the-prediction-of-in-vivo-drug-drug-interactions-between-rivaroxaban-and-anti-arrhythmic-agents-based-on-in-vitro-inhibition-studies
#14
Eleanor Jing Yi Cheong, Janice Jia Ni Goh, Yanjun Hong, Gopalakrishnan Venkatesan, Yuanjie Liu, Gigi Ngar Chee Chiu, Pipin Kojodjojo, Eric Chun Yong Chan
Rivaroxaban, a direct Factor Xa inhibitor, is indicated for stroke prevention in non-valvular atrial fibrillation (AF). Studies have revealed that the clearance of rivaroxaban is largely attributed to CYP3A4, CYP2J2 metabolism and P-gp efflux pathways. Amiodarone and dronedarone are anti-arrhythmic agents employed in AF management. Amiodarone, dronedarone and their major metabolites, N-desethylamiodarone (NDEA) and N-desbutyldronedarone (NDBD) demonstrate inhibitory effects on CYP3A4 and CYP2J2 with FDA recommended probe substrates...
January 4, 2017: Drug Metabolism and Disposition: the Biological Fate of Chemicals
https://www.readbyqxmd.com/read/28052106/a-prediction-algorithm-for-drug-response-in-patients-with-mesial-temporal-lobe-epilepsy-based-on-clinical-and-genetic-information
#15
Mariana S Silva-Alves, Rodrigo Secolin, Benilton S Carvalho, Clarissa L Yasuda, Elizabeth Bilevicius, Marina K M Alvim, Renato O Santos, Claudia V Maurer-Morelli, Fernando Cendes, Iscia Lopes-Cendes
Mesial temporal lobe epilepsy is the most common form of adult epilepsy in surgical series. Currently, the only characteristic used to predict poor response to clinical treatment in this syndrome is the presence of hippocampal sclerosis. Single nucleotide polymorphisms (SNPs) located in genes encoding drug transporter and metabolism proteins could influence response to therapy. Therefore, we aimed to evaluate whether combining information from clinical variables as well as SNPs in candidate genes could improve the accuracy of predicting response to drug therapy in patients with mesial temporal lobe epilepsy...
2017: PloS One
https://www.readbyqxmd.com/read/28050888/a-new-cyp3a5-3-and-cyp3a4-22-cluster-influencing-tacrolimus-target-concentrations-a-population-approach
#16
Franc Andreu, Helena Colom, Laure Elens, Teun van Gelder, Ronald H N van Schaik, Dennis A Hesselink, Oriol Bestard, Joan Torras, Josep M Cruzado, Josep M Grinyó, Nuria Lloberas
BACKGROUND: Single nucleotide polymorphisms (SNPs) in the CYP3A5 and CYP3A4 genes have been reported to be an important cause of variability in the pharmacokinetics of tacrolimus in renal transplant patients. The aim of this study was to merge all of the new genetic information available with tacrolimus pharmacokinetics to generate a more robust population model with data from renal transplant recipients. METHODS: Tacrolimus exposure data from 304 renal transplant recipients were collected throughout the first year after transplantation and were simultaneously analyzed with a population pharmacokinetic approach using NONMEM(®) version 7...
January 3, 2017: Clinical Pharmacokinetics
https://www.readbyqxmd.com/read/28049954/no-effect-of-slco1b1-and-cyp3a4-5-polymorphisms-on-the-pharmacokinetics-and-pharmacodynamics-of-ticagrelor-in-healthy-chinese-male-subjects
#17
Mupeng Li, Yaodong Hu, Huilan Li, Zhipeng Wen, Xiaolei Hu, Daoyu Zhang, Yanjiao Zhang, Jian Xiao, Jie Tang, Xiaoping Chen
Ticagrelor is a direct-acting P2Y12 receptor antagonist. It is rapidly absorbed and partly metabolized to the active metabolite AR-C124910XX by CYP3A4 and CYP3A5. Three genetic loci (SLCO1B1, CYP3A4, and UGT2B7) were reported to affect ticagrelor pharmacokinetics. This study aimed to investigate the possible effects of SLCO1B1 and CYP3A4/5 genetic polymorphisms on the pharmacokinetics and pharmacodynamics of ticagrelor in healthy Chinese male volunteers. Eighteen healthy male volunteers who participated in pharmacogenetics study of ticagrelor were genotyped for SLCO1B1 rs113681054, SLCO1B1*5 (rs4149056), CYP3A4*1G (rs2242480), and CYP3A5*3 (rs776746)...
2017: Biological & Pharmaceutical Bulletin
https://www.readbyqxmd.com/read/28044353/donor-cyp3a5-genotype-influences-tacrolimus-disposition-on-the-first-day-after-paediatric-liver-transplantation
#18
Pier Luigi Calvo, Loredana Serpe, Andrea Brunati, Antonello Nonnato, Daniela Bongioanni, Dominic Dell Olio, Michele Pinon, Carlo Ferretti, Francesco Tandoi, Giulia Carbonaro, Mauro Salizzoni, Antonio Amoroso, Renato Romagnoli, Roberto Canaparo
AIM: The aim of our study was to investigate the influence of the CYP3A4/5 genotype in paediatric liver transplant recipients and donors and what contribution age and gender make to tacrolimus disposition on the first day after transplantation. METHODS: The contribution of the CYP3A4/5 genotype in paediatric liver transplant recipients and donors to the tacrolimus blood trough concentrations (C0 ) and tacrolimus concentration/weight-adjusted dose ratio on day one was evaluated in 67 liver transplanted children: 33 boys and 34 girls, mean age 4...
January 3, 2017: British Journal of Clinical Pharmacology
https://www.readbyqxmd.com/read/28043194/differential-regulation-of-intestinal-efflux-transporters-by-pregnancy-in-mice
#19
Jamie E Moscovitz, Gabriel Yarmush, Guadalupe Herrera-Garcia, Grace L Guo, Lauren M Aleksunes
1. In the intestines, the nuclear receptors farnesoid X receptor (Fxr) and pregnane X receptor (Pxr) regulate the transcription of metabolizing enzymes and transporters that dictate the absorption of nutrients and xenobiotics. 2. Here, we sought to determine whether Fxr and Pxr signaling pathways are disrupted in response to high-circulating concentrations of steroid hormones late in pregnancy leading to altered transporter expression. To test this, ileum were collected from virgin and pregnant C57BL/6 mice on gestation days 14, 17 and 19...
January 3, 2017: Xenobiotica; the Fate of Foreign Compounds in Biological Systems
https://www.readbyqxmd.com/read/28042936/effect-of-type-2-diabetes-mellitus-on-the-pharmacokinetics-and-transplacental-transfer-of-nifedipine-in-hypertensive-pregnant-women
#20
Gabriela Campos de Oliveira Filgueira, Osmany Alberto Silva Filgueira, Daniela Miarelli Carvalho, Maria Paula Marques, Elaine Christine Dantas Moisés, Geraldo Duarte, Vera Lucia Lanchote, Ricardo Carvalho Cavalli
AIMS: Diabetes mellitus can inhibit CYP3A4, an enzyme responsible for the metabolism of nifedipine, used for the treatment of hypertension in pregnant women. We aimed to assess the effect of type 2 diabetes mellitus (T2DM) on the pharmacokinetics, placental transfer and distribution of nifedipine in amniotic fluid in hypertensive pregnant women. METHODS: The study was conducted on 12 hypertensive pregnant women (control group - CG) and 10 hypertensive pregnant women with T2DM taking slow-release nifedipine (20 mg, 12/12 hours)...
January 2, 2017: British Journal of Clinical Pharmacology
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