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Drug Metabolism and Pharmacokinetics

Atsushi Iwamura, Miki Nakajima, Shingo Oda, Tsuyoshi Yokoi
Idiosyncratic drug toxicity (IDT) is a serious problem in drug development. Reactive metabolites are postulated to be one of the causes for IDT. Conjugated metabolites are generally non-reactive except for acyl glucuronides (AGs), which are sufficiently reactive to covalently bind to endogenous proteins. Thus, it has been suggested that AGs would contribute to IDT caused by carboxylic acid-containing drugs. Glucuronidation of a carboxylate residue is catalyzed by UDP-glucuronosyltransferase 1A and 2B isoforms...
November 23, 2016: Drug Metabolism and Pharmacokinetics
Toru Usui, Dean J Naisbitt
A clinical association between a specific human leukocyte antigen (HLA) allele and idiosyncratic adverse drug reactions (IADRs) is a strong indication that IADRs are mediated by the adaptive immune system. For example, it is well-established that HLA-B*15:02 and HLA-B*57:01 are associated with carbamazepine-induced Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) and abacavir-induced hypersensitivity/flucloxacillin-induced liver injury, respectively. Drug-specific T-cells whose response is restricted by specific HLA risk alleles have been detected from IADR patients, also suggesting an adaptive immune pathogenesis...
November 18, 2016: Drug Metabolism and Pharmacokinetics
Kazuo Takayama, Hiroyuki Mizuguchi
Because drug-induced liver injury is one of the main reasons for drug development failures, it is important to perform drug toxicity screening in the early phase of pharmaceutical development. Currently, primary human hepatocytes are most widely used for the prediction of drug-induced liver injury. However, the sources of primary human hepatocytes are limited, making it difficult to supply the abundant quantities required for large-scale drug toxicity screening. Therefore, there is an urgent need for a novel unlimited, efficient, inexpensive, and predictive model which can be applied for large-scale drug toxicity screening...
October 26, 2016: Drug Metabolism and Pharmacokinetics
Makoto Kataoka, Chie Kojima, Kazuki Ueda, Keiko Minami, Haruki Higashino, Shinji Sakuma, Kazutaka Togashi, Kuninori Mutaguchi, Shinji Yamashita
The purpose of the present study is to demonstrate a useful approach (isotope-IV method) for analyzing drug-drug interactions (DDIs) following the oral administration of drugs using stable isotope-labeled compounds. Verapamil hydrochloride (VER) was used as a drug model. Deuterium-labeled VER (VER-d6, 0.005 mg/kg) was intravenously administered to rats with or without a pre-treatment with 1-aminobenzotriazole (ABT, 100 mg/kg), a potent CYP inhibitor, 1.5 h after the oral administration of VER (1 mg/kg)...
December 2016: Drug Metabolism and Pharmacokinetics
Kimie Sai, Kouji Kajinami, Hironobu Akao, Mizuho Iwadare, Ryoko Sato-Ishida, Yasuyuki Kawai, Kenji Takeda, Takashi Tanimoto, Takashi Yamano, Takashi Akasaka, Tatsuro Ishida, Ken-Ichi Hirata, Keijiro Saku, Shusuke Yagi, Takeshi Soeki, Masataka Sata, Masafumi Ueno, Shunichi Miyazaki, Aya Shiraki, Jun-Ichi Oyama, Koichi Node, Koichi Sugamura, Hisao Ogawa, Kouichi Kurose, Keiko Maekawa, Yumiko Matsuzawa, Takuya Imatoh, Ryuichi Hasegawa, Yoshiro Saito
Statin-related myopathy (SRM) is a clinically important adverse reaction. Recent pharmacogenetic research, mainly in non-Asian populations, have indicated clinical relevance of some of genetic biomarkers to SRM, but predictive markers for SRM in Asian populations including Japanese has not yet been established. This study was aimed to identify clinically important genetic markers associated with SRM in Japanese patients. Allele frequencies of the three reported candidate markers - SLCO1B1 rs4149056, RYR2 rs2819742, and GATM rs9806699 - and carrier frequencies of HLA types were compared between patients with SRM patients (n = 52) and healthy Japanese subjects (n = 2878 or 86 (for rs9806699) as controls)...
December 2016: Drug Metabolism and Pharmacokinetics
Eunyoung Kim, Chunhwa Ihm, Wonku Kang
Aceclofenac has been used widely as a potent analgesic and anti-inflammatory drug. Aceclofenac is converted to 4'-hydroxyaceclofenac and diclofenac via CYP2C9-mediated hydroxylation and hydrolysis, respectively. CYP2C9 also mediates the hydroxylation of diclofenac to yield 4'-hydroxydiclofenac and the hydrolysis of 4'-hydroxyaceclofenac to 4'-hydroxydiclofenac. We aimed to model the metabolism of aceclofenac in volunteers using a compartmental modeling approach. After an oral dose of 100 mg aceclofenac in volunteers, plasma concentrations of aceclofenac and its three metabolites were measured...
December 2016: Drug Metabolism and Pharmacokinetics
Masahiro Iwaki, Toshiro Niwa, Saya Bandoh, Megumi Itoh, Hitomi Hirose, Atsushi Kawase, Hiroshi Komura
To evaluate the relative contribution of cytochrome P450 (CYP) isoforms responsible for carvedilol (CAR) oxidation, enantioselective metabolism of CAR was investigated in human liver microsomes (HLMs) and recombinant human CYPs by using the substrate depletion assay. CYP2D6 exhibited the highest contribution to the metabolism of R-CAR, followed by CYP3A4, CYP1A2, and CYP2C9, whereas the metabolism of the S-enantiomer was mainly mediated by CYP1A2, followed by CYP2D6 and CYP3A4. In HLMs, metabolism of R- and S-CAR was markedly inhibited by quinidine; R-CAR metabolism (57-61% decrease) was more inhibited than S-CAR metabolism (37-43% decrease), and furafylline and ketoconazole almost equally inhibited metabolism of both enantiomers by 25-32% and 30-50%, respectively...
December 2016: Drug Metabolism and Pharmacokinetics
Mikihisa Takano, Ryosuke Naka, Yoshihiro Sasaki, Saori Nishimoto, Ryoko Yumoto
The effect of cigarette smoke extract (CSE) on P-glycoprotein (P-gp) function in the distal lung is unclear. In this study, we first examined the expression and function of P-gp and the effect of CSE in rat primary cultured alveolar epithelial cells. The expression of P-gp protein was observed in type I-like cells, but not in type II cells. In type I-like cells, rhodamine 123 (Rho123) accumulation was enhanced by various P-gp inhibitors such as verapamil and cyclosporine A. In addition, the expression of P-gp mRNAs, mdr1a and mdr1b, as well as P-gp activity increased along with the transdifferentiation...
December 2016: Drug Metabolism and Pharmacokinetics
Yuki Nomura, Hiromi Iitsuka, Junko Toyoshima, Kentaro Kuroishi, Toshifumi Hatta, Atsunori Kaibara, Masataka Katashima, Selina Moy, Taiji Sawamoto
Mirabegron, the first selective β3-adrenoceptor agonist for the treatment of overactive bladder (OAB), inhibits cytochrome P450 isozyme CYP2D6. This study was performed in Japanese healthy postmenopausal female volunteers to assess any pharmacokinetic drug interaction between mirabegron and tolterodine, another OAB drug and a sensitive substrate of CYP2D6. Tolterodine 4 mg was orally administered from Days 1-7 and co-administered with mirabegron 50 mg from Days 8-14. Mirabegron 50 mg increased maximum concentration (Cmax) and area under the concentration-time curve from zero to 24 h after dosing (AUC24h) of tolterodine by 2...
December 2016: Drug Metabolism and Pharmacokinetics
Songhee Han, Gun-Su Cha, Young-Jin Chun, Chang Hoon Lee, Donghak Kim, Chul-Ho Yun
Human CYP4A11 is the major ω-hydroxylase of fatty acids in the liver and kidneys. It produces 20-hydroxyeicosatetraenoic acid as well as hydroxylates fatty acids. In this study, we investigated the biochemical properties of three alleles of CYP4A11: W126R, K276T, and S353G. Site-directed mutagenesis of the wild type CYP4A11 was performed, to construct the W126R, K276T, and S353G variant clones. The CYP4A11 wild type and variant constructs were heterologously expressed in Escherichia coli. CO-binding spectra showed the expression of the wild type, K276T and S353G variants, indicating the functional P450 holoenzyme...
December 2016: Drug Metabolism and Pharmacokinetics
Kayoko Kanamitsu, Ryosuke Arakawa, Yuichi Sugiyama, Tetsuya Suhara, Hiroyuki Kusuhara
The effect of drugs in the central nervous system (CNS) is closely related to occupancy of their target receptor. In this study, we integrated plasma concentrations, in vitro/in vivo data for receptor or protein binding, and in silico data, using a physiologically based pharmacokinetic model, to examine the predictability of receptor occupancy in humans. The occupancy of the dopamine D2 receptor and the plasma concentrations of the antipsychotic drugs quetiapine and perospirone in humans were collected from the literature or produced experimentally...
December 2016: Drug Metabolism and Pharmacokinetics
Hang He, Ya-Li Nie, Jiang-Feng Li, Xiang-Guang Meng, Wei-Hong Yang, Yu-Long Chen, Shu-Jie Wang, Xiaochao Ma, Quan-Cheng Kan, Li-Rong Zhang
CYP3A4 and CYP3A7 are generally served as the major adult and fetal liver forms, respectively, and exhibited a developmental switch during liver maturation. The objective of this study was to explore the potential mechanisms associated with the developmental switch of CYP3A4 and CYP3A7 in the Chinese Han population. We analyzed CYP3A4/7, nuclear receptors, and epigenetic modifications in human liver samples. We found that the expression levels of CYP3A4 mRNA in adults were significantly higher than the levels in fetus...
December 2016: Drug Metabolism and Pharmacokinetics
Toshihide Higashino, Hirotaka Matsuo, Masayuki Sakiyama, Akiyoshi Nakayama, Takahiro Nakamura, Tappei Takada, Hiraku Ogata, Yusuke Kawamura, Makoto Kawaguchi, Mariko Naito, Sayo Kawai, Yuzo Takada, Hiroshi Ooyama, Hiroshi Suzuki, Nariyoshi Shinomiya
PDZ domain containing 1 (PDZK1) is a scaffold protein that organizes a transportsome and regulates several transporters' functions including urate and drug transporters. Therefore, PDZK1 in renal proximal tubules may affect serum uric acid levels through PDZK1-binding renal urate transporters. Two previous studies in Japanese male population reported that a PDZK1 single nucleotide polymorphism (SNP), rs12129861, was not associated with gout. In the present study, we performed a further association analysis between gout and rs12129861 in a different large-scale Japanese male population and a meta-analysis with previous Japanese population studies...
December 2016: Drug Metabolism and Pharmacokinetics
Noriaki Hirayama
Idiosyncratic drug toxicities (IDTs) caused by certain drugs are a significant cause of morbidity and mortality for patients. As IDTs are not normally detected even during clinical trials, it is difficult to foresee the risk during the early stage of drug development. Prediction of potential IDTs at the earliest possible opportunity is highly desirable. The strong associations between a particular IDT and a specific human leukocyte antigen (HLA) have been reported and the recent study has disclosed that the direct interaction between a drug in question and the HLA molecule triggers the onset of IDT...
October 18, 2016: Drug Metabolism and Pharmacokinetics
Yoshiyuki Kubo, Shizuka Yahata, Satoshi Miki, Shin-Ichi Akanuma, Ken-Ichi Hosoya
Riboflavin (vitamin B2) supply to the retina across the inner blood-retinal barrier (BRB) was investigated. In rats, the apparent influx permeability clearance of [(3)H]riboflavin (62.8 μL/(min·g retina)) was much higher than that of a non-permeable paracellular marker, suggesting the facilitative influx transport of riboflavin across the BRB. The retinal uptake index (RUI) of [(3)H]riboflavin was 59.0%, and significantly reduced by flavin adenine dinucleotide (FAD), but not by l-ascorbic acid, suggesting the substrate specificity of riboflavin transport...
October 8, 2016: Drug Metabolism and Pharmacokinetics
Almudena Sánchez-Martín, Salvador Cabrera Figueroa, Raquel Cruz, Liliana Porras-Hurtado, Fernando Calvo-Boyero, Mahmood Rasool, Alfonso Domínguez-Gil Hurlé, Angel Carracedo
Genetic factors have a significant impact on the PK variability of EFV, much higher than other non-genetic factors, such as demography. In this work we have performed a comprehensive PG analysis of genes encoding the major metabolizing enzymes and transporters of EFV, establishing a clear relationship between the PK parameters and genetic factors, which explain 50% of the variability in EFV PK parameters. The most relevant associations for metabolizing enzymes were found in CYP2B6 (rs3745274), in agreement with previous studies...
October 2016: Drug Metabolism and Pharmacokinetics
Yasushi Yamazoe, Kazumi Ito, Yoshiya Yamamura, Ryutaro Iwama, Kouichi Yoshinari
This prediction system is based on placements of CYP1A2-substrates on a hexagonal-grid template in a way following the rule generated from the relationship of the substrate-structure and selective-area uses on the template, and also the rule for a triggering-event to initiate the catalytic reactions. Clear relationship found between the placements and preferred-order of regioselective reactions from the comparison of experimental data of polyaromatic hydrocarbon (PAH)-substrates was implemented in this system...
October 2016: Drug Metabolism and Pharmacokinetics
Michał Romański, Anna Kasprzyk, Agnieszka Karbownik, Franciszek K Główka
Treosulfan (TREO) has an established position in chemotherapy of advanced ovarian cancer but has been also applied in uveal melanoma patients. Moreover, it is used as an orphan drug for a myeloablative conditioning prior to stem cell transplantation. In this paper, biodistribution of prodrug TREO and its active monoepoxide (S,S-EBDM) and diepoxide (S,S-DEB) into aqueous humor of the eye was studied for the first time. For that purpose, alone TREO and the mixture of TREO, S,S-EBDM and S,S-DEB were administered intravenously to New Zealand White rabbits...
October 2016: Drug Metabolism and Pharmacokinetics
Yoshiyuki Shirasaka, Nora Lee, Weibin Zha, David Wagner, Joanne Wang
Metformin is widely used for the treatment of type II diabetes mellitus. It was reported to be substrate of OCT3/Oct3, which is expressed in the brush boarder membrane of the enterocytes. However, the role of OCT3/Oct3 in the intestinal absorption process of metformin remains obscure. In the present study, we aimed to clarify the impact of Oct3 on the oral bioavailability and pharmacokinetics of metformin in mice, by means of in vivo pharmacokinetic study using wild-type (Oct3(+/+)) and Oct3-knockout (Oct3(-/-)) mice...
October 2016: Drug Metabolism and Pharmacokinetics
Masanori Nakakariya, Akihiko Goto, Nobuyuki Amano
DDI could be caused by the inhibition of OATP-mediated hepatic uptakes. The aim of this study is to set the risk criteria for the compounds that would cause DDI via OATP inhibition at the drug discovery stage. The IC50 values of OATP inhibitors for human OATP-mediated atorvastatin uptake were evaluated in the expression system. In order to set the risk criteria for OATP inhibition, the relationship was clarified between OATP inhibitory effect and severe adverse effects of OATP substrates, rhabdomyolysis, hyperbilirubinemia and jaundice...
October 2016: Drug Metabolism and Pharmacokinetics
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