Fluorescent indicator displacement assay for the discovery of UGGAA repeat-targeted small molecules.

We report that a selective fluorescent indicator NBD-NCD for UGGAA repeats resulted in fluorescence quenching upon binding to RNA and recovered the fluorescence by displacing NBD-NCD with UGGAA repeat-targeted small molecules. The fluorescent indicator displacement assay using NBD-NCD can detect the interaction of small molecules with UGGAA repeats.

Estimation of changes in serum creatinine and creatinine clearance caused by renal transporter inhibition in healthy subjects.

Creatinine is excreted into urine by glomerular filtration and renal tubular secretion through drug transporters such as organic anion transporter 2 (OAT2), organic cation transporter 2 (OCT2), OCT3, multidrug and toxin extrusion protein 1 (MATE1), and MATE2-K. We aimed to investigate whether our method for estimating percentage changes in serum creatinine concentration (SCr) and creatinine clearance (CL) from the baseline is applicable for studying renal transporter inhibitors. We tested 14 compounds (cimetidine, cobicistat, dolutegravir, dronedarone, DX-619, famotidine, INCB039110, nizatidine, ondansetron, pyrimethamine, rabeprazole, ranolazine, trimethoprim, and vandetanib), which were reported to cause reversible changes in SCr and/or CL in healthy subjects excluding elderly.

Functional characterization for polymorphic organic anion transporting polypeptides (OATP/SLCO1B1, 1B3, 2B1) of monkeys recombinantly expressed with various OATP probes.

The hepatic uptake of clinical drugs mediated by human hepatic organic anion transporting polypeptides (OATP/SLCO) has been reported extensively. In this study, hepatic uptake by recombinantly expressed monkey OATP1B1, OATP1B3 and OATP2B1 was investigated using three human OATP1B1 and OATP1B3 substrates (pitavastatin, pravastatin and rosuvastatin) and one OATP1B3 substrate (telmisartan), as the governmental drug interaction guidelines recommend, and seven reported clinical drugs. The uptake of known human probes into recombinant OATP-expressing cells was significantly greater than that of mock cells.

Quantitative analysis of elevation of serum creatinine via renal transporter inhibition by trimethoprim in healthy subjects using physiologically-based pharmacokinetic model.

Serum creatinine (SCr) levels rise during trimethoprim therapy for infectious diseases. This study aimed to investigate whether the elevation of SCr can be quantitatively explained using a physiologically-based pharmacokinetic (PBPK) model incorporating inhibition by trimethoprim on tubular secretion of creatinine via renal transporters such as organic cation transporter 2 (OCT2), OCT3, multidrug and toxin extrusion protein 1 (MATE1), and MATE2-K. Firstly, pharmacokinetic parameters in the PBPK model of trimethoprim were determined to reproduce the blood concentration profile after a single intravenous and oral administration of trimethoprim in healthy subjects.

Evaluation of expression and glycosylation status of UGT1A10 in Supersomes and intestinal epithelial cells with a novel specific UGT1A10 monoclonal antibody.

UDP-Glucuronosyltransferases (UGTs) are major phase II drug-metabolizing enzymes. Each member of the UGT family exhibits a unique but occasionally overlapping substrate specificity and tissue-specific expression pattern. Earlier studies have reported that human UGT1A10 is expressed in the gastrointestinal tract at the mRNA level, but the evaluation at the protein level, especially tissue or cellular localization, has lagged behind because of the lack of a specific antibody.

Precise prediction of activators for the human constitutive androstane receptor using structure-based three-dimensional quantitative structure-activity relationship methods.

The constitutive androstane receptor (CAR, NR1I3) regulates the expression of numerous drug-metabolizing enzymes and transporters. The upregulation of various enzymes, including CYP2B6, by CAR activators is a critical problem leading to clinically severe drug-drug interactions (DDIs). To date, however, few effective computational approaches for identifying CAR activators exist.

Pre-incubation with cyclosporine A potentiates its inhibitory effects on pitavastatin uptake mediated by recombinantly expressed cynomolgus monkey hepatic organic anion transporting polypeptide.

Cyclosporine A, an inhibitor of hepatic organic anion transporting polypeptides (OATPs), reportedly increased plasma concentrations of probe substrates, although its maximum unbound blood concentrations were lower than the experimental half-maximal inhibitory (IC ) concentrations. Pre-incubation with cyclosporine A in vitro before simultaneous incubation with probes has been reported to potentiate its inhibitory effects on recombinant human OATP-mediated probe uptake. In the present study, the effects of cyclosporine A and rifampicin on recombinant cynomolgus monkey OATP-mediated pitavastatin uptake were investigated in pre- and simultaneous incubation systems.

Zomepirac Acyl Glucuronide Is Responsible for Zomepirac-Induced Acute Kidney Injury in Mice.

Glucuronidation, an important phase II metabolic route, is generally considered to be a detoxification pathway. However, acyl glucuronides (AGs) have been implicated in the toxicity of carboxylic acid drugs due to their electrophilic reactivity. Zomepirac (ZP) was withdrawn from the market because of adverse effects such as renal toxicity.

Tissue distribution of teneligliptin in rats and comparisons with data reported for other dipeptidyl peptidase-4 inhibitors.

We investigated the tissue distribution of teneligliptin, a dipeptidyl peptidase (DPP)-4 inhibitor, in rats, and compared it with tissue distributions previously reported for other DPP-4 inhibitors. Following the oral administration of [ C]teneligliptin to Sprague-Dawley rats, it was predominantly distributed to the kidney and liver, followed by the lung, spleen, and pituitary gland. The elimination half-life (t ) of [ C]teneligliptin was 68.

Toxicological evaluation of acyl glucuronides utilizing half-lives, peptide adducts, and immunostimulation assays.

Chemical reactivity of acyl glucuronides (AGs) is believed to be involved in the toxicity of carboxylic acid-containing drugs. Both direct and immune-mediated toxicity have been suggested as possible mechanisms of toxicity; however, it remains unclear. In the present study, we performed assays of half-lives, peptide adducts, and immunostimulation to evaluate the potential risk of AGs of 21 drugs and analyzed the relationship to the toxic category.

Benzydamine N-oxygenation as an index for flavin-containing monooxygenase activity and benzydamine N-demethylation by cytochrome P450 enzymes in liver microsomes from rats, dogs, monkeys, and humans.

Benzydamine is an anti-inflammatory drug that undergoes flavin-containing monooxygenase (FMO)-dependent metabolism to benzydamine N-oxide; however, benzydamine N-demethylation is also catalyzed by liver microsomes. In this study, benzydamine N-oxygenation and N-demethylation mediated by liver microsomes from rats, dogs, monkeys, and humans were characterized comprehensively. Values of the maximum velocity/Michaelis constant ratio for benzydamine N-oxygenation by liver microsomes from dogs and rats were higher than those from monkeys and humans, despite roughly similar rates of N-demethylation in the four species.

Key determinants of the circulatory exposure of organic anions: differences in hepatic uptake between multidrug resistance-associated protein 2 (Mrp2)-deficient rats and wild-type rats.

1. Raloxifene-6-glucuronide (R6G) is a substrate of rat multidrug resistance-associated protein 2 (Mrp2), a transporter responsible for biliary excretion of organic anions. 2.

Role of cytochrome P450-mediated metabolism and identification of novel thiol-conjugated metabolites in mice with phenytoin-induced liver injury.

Phenytoin, 5,5-diphenylhydantoin (DPH), is widely used as an anticonvulsant agent. Severe hepatic injury rarely occurs in patients who received DPH. The development of liver injury is thought to be caused by reactive metabolites; however, the metabolites suggested to contribute to hepatotoxicity have not yet been detected in vivo and their effect on developing the liver injury is largely unknown.

Pitavastatin as an in vivo probe for studying hepatic organic anion transporting polypeptide-mediated drug-drug interactions in cynomolgus monkeys.

Drug-drug interactions (DDIs) caused by the inhibition of hepatic uptake transporters such as organic anion transporting polypeptide (OATP) can affect therapeutic efficacy and cause adverse reactions. We investigated the potential utility of pitavastatin as an in vivo probe substrate for preclinically studying OATP-mediated DDIs using cynomolgus monkeys. Cyclosporine A (CsA) and rifampicin (RIF), typical OATP inhibitors, inhibited active uptake of pitavastatin into monkey hepatocytes with half-maximal inhibitory concentration values comparable with those in human hepatocytes.

Metabolism and disposition of the dipeptidyl peptidase IV inhibitor teneligliptin in humans.

1. The absorption, metabolism and excretion of teneligliptin were investigated in healthy male subjects after a single oral dose of 20 mg [(14)C]teneligliptin. 2.

Impact of intestinal glucuronidation on the pharmacokinetics of raloxifene.

Raloxifene is extensively glucuronidated in humans, effectively reducing its oral bioavailability (2%). It was also reported to be glucuronidated in preclinical animals, but its effects on the oral bioavailability have not been fully elucidated. In the present study, raloxifene and its glucuronides in the portal and systemic blood were monitored in Gunn rats deficient in UDP-glucuronosyltransferase (UGT) 1A, Eisai hyperbilirubinemic rats (EHBRs), which hereditarily lack multidrug resistance-associated protein (MRP) 2, and wild-type rats after oral administration.

Alprazolam as an in vivo probe for studying induction of CYP3A in cynomolgus monkeys.

Induction of the cytochrome P450 (P450) enzyme is a major concern in the drug discovery processes. To predict the clinical significance of enzyme induction, it is helpful to investigate pharmacokinetic alterations of a coadministered drug in a suitable animal model. In this study, we focus on the induction of CYP3A, which is involved in the metabolism of approximately 50% of marketed drugs and is inducible in both the liver and intestine.

In vivo evaluation of drug-drug interaction via mechanism-based inhibition by macrolide antibiotics in cynomolgus monkeys.

Irreversible inhibition, characterized as mechanism-based inhibition (MBI), of cytochrome P450 in drugs has to be avoided for their safe use. A comprehensive assessment of drug-drug interaction (DDI) potential is important during the drug discovery process. In the present study, we evaluated the effects of macrolide antibiotics, erythromycin (ERM), clarithromycin (CAM), and azithromycin (AZM), which are mechanism-based inhibitors of CYP3A, on biotransformation of midazolam (MDZ) in monkeys.

Effect of oral ketoconazole on oral and intravenous pharmacokinetics of simvastatin and its acid in cynomolgus monkeys.

Drugs with potential drug-drug interactions (DDIs) may have a limited scope of use and, at worst, may have to be withdrawn from the market. Therefore, during the drug discovery process it is important to select drug candidates with reduced potential for DDIs. In the present study, we evaluated the pharmacokinetics of simvastatin (SV), a typical substrate for cytochrome P450 (P450) 3A, and examined the DDI between SV and ketoconazole (KTZ), a P450 3A inhibitor, in monkeys.

Effect of oral ketoconazole on intestinal first-pass effect of midazolam and fexofenadine in cynomolgus monkeys.

Because the expression of drug-metabolizing enzymes and drug efflux transporters has been shown in the intestine, the contribution of this tissue to the first-pass effect has become of significant interest. Consequently, a comprehensive understanding of the absorption barriers in key preclinical species would be useful for the precise characterization of drug candidates. In the present investigation, we evaluated the intestinal first-pass effect of midazolam (MDZ) and fexofenadine (FEX), typical substrates for CYP3A and P-glycoprotein (P-gp), respectively, with ketoconazole (KTZ) as a potent dual CYP3A/P-gp inhibitor in cynomolgus monkeys.

Characterization of hepatobiliary transport systems of a novel alpha4beta1/alpha4beta7 dual antagonist, TR-14035.

Purpose: Our previous pharmacokinetic studies have demonstrated that TR-14035, a novel dual antagonist for alpha4beta1/alpha4beta7 integrin, selectively and strongly accumulated in the liver and was mainly excreted in bile as an unchanged drug. In the present study, we investigated the hepatobiliary transport system in detail.

Materials And Methods: Uptake by hepatocytes and organic anion transporting polypeptide (OATP)-expressing Xenopus laevis oocytes or Flp-In-293 cells was performed in vitro.

Identification of human UDP-glucuronosyltransferase isoform(s) responsible for the glucuronidation of 2-(4-chlorophenyl)- 5-(2-furyl)-4-oxazoleacetic acid (TA-1801A).

We characterized the hepatic and intestinal UDP-glucuronosyltransferase (UGT) isoform(s) responsible for the glucuronidation of 2-(4-chlorophenyl)-5-(2-furyl)-4-oxazoleacetic acid (TA-1801A) in humans through several in vitro mechanistic studies. Assessment of a panel of recombinant UGT isoforms revealed the TA-1801A glucuronosyltransferase activity of UGT1A1, UGT1A3, UGT1A7, UGT1A9, and UGT2B7. Kinetic analyses of the TA-1801A glucuronidation by recombinant UGT1A1, UGT1A3, UGT1A9, and UGT2B7 showed that the K(m) value for UGT2B7 was apparently consistent with those in human liver and jejunum microsomes.

Glucuronidation of 2-(4-chlorophenyl)-5-(2-furyl)-4-oxazoleacetic acid (TA-1801A) in humans: species differences in liver and intestinal microsomes.

The metabolism of ethyl 2-(4-chlorophenyl)-5-(2-furyl)-4-oxazoleacetate (TA-1801), a potent hypolipidemic agent, was studied in humans after oral administration and compared with that found in rats, rabbits, and dogs previously. Hydrolysis of the ethyl ester to produce metabolite M1 (TA-1801 active form; TA-1801A) is the first metabolic step and the subsequent biotransformation includes the glucuronidation to form the metabolite M4 and the oxidation to form the metabolites M2 and M3. The metabolism of TA-1801 in humans was qualitatively similar to that in the experimental animals studied, although species differences were seen in the amount of metabolites.