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1.
J Clin Pharmacol ; 57(4): 524-535, 2017 04.
Article in English | MEDLINE | ID: mdl-27681484

ABSTRACT

The purpose of the present study was to evaluate the pharmacokinetics of beraprost sodium (BPS) and its active enantiomer, BPS-314d, in Japanese subjects with impaired kidney function. The plasma and urine concentrations of BPS and BPS-314d were measured following the single oral administration of 120 µg of BPS as the sustained-release tablet, TRK-100STP, under fasting conditions to 18 subjects with impaired kidney function (stage 2, 3, and 4 chronic kidney disease [CKD] as categorized by the estimated glomerular filtration rate) and to 6 age-, body weight-, and gender-matched subjects with normal kidney function (stage 1 CKD). The Cmax values (mean ± SD) of BPS in stage 1, 2, 3, and 4 CKD, respectively, were 84.9 ± 22.9, 119.8 ± 36.4, 190.6 ± 137.3, and 240.2 ± 110.5 pg/mL; its AUC0-48h were 978 ± 226, 1252 ± 427, 1862 ± 964, and 1766 ± 806 pg·h/mL, respectively, and its cumulative urinary excretion rates were 0.704 ± 0.351%, 0.638 ± 0.292%, 0.485 ± 0.294%, and 0.159 ± 0.136%. The Cmax values of BPS-314d were 22.4 ± 6.4, 30.8 ± 8.5, 46.7 ± 30.6, and 54.4 ± 25.2 pg/mL, its AUC0-48h were 155 ± 56, 226 ± 67, 341 ± 176, and 329 ± 143 pg·h/mL, and its cumulative urinary excretion rates were 0.428 ± 0.242%, 0.349 ± 0.179%, 0.356 ± 0.270%, and 0.096 ± 0.099%, respectively. Adverse events were reported in 2 subjects with stage 2 CKD and 1 subject with stage 4 CKD. The Cmax and AUC0-48h of BPS and BPS-314d were higher based on the severity of impaired kidney function. No relationship was observed between the incidence of adverse events and the severity, and tolerability was confirmed. We consider that dose adjustment is not necessary, but BPS is more carefully treated in patients with impaired kidney function.


Subject(s)
Epoprostenol/analogs & derivatives , Renal Insufficiency/blood , Renal Insufficiency/urine , Administration, Oral , Aged , Delayed-Action Preparations , Epoprostenol/administration & dosage , Epoprostenol/pharmacokinetics , Female , Humans , Male , Middle Aged , Platelet Aggregation Inhibitors/administration & dosage , Platelet Aggregation Inhibitors/pharmacokinetics , Protein Binding/physiology , Renal Insufficiency/drug therapy
2.
Drug Metab Dispos ; 42(5): 885-9, 2014 May.
Article in English | MEDLINE | ID: mdl-24595681

ABSTRACT

The aim of this study was to optimize methods for quantifying 13 uridine 5'-diphosphate-glucuronosyltransferase (UGT) isoforms (UGT1A1, 1A3, 1A4, 1A6, 1A7, 1A8, 1A9, 1A10, 2B4, 2B7, 2B10, 2B15, and 2B17) in human liver, intestinal, and kidney microsomes, and in recombinant human UGT-expressing insect cell membranes (rhUGTs) by targeted peptide-based quantification using liquid chromatography-tandem mass spectrometry. Production of targeted peptides was compared by combining three denaturing agents (urea, sodium deoxycholate, and octyl glucoside) and three denaturing temperatures (37°C, 60°C, and 95°C) followed by tryptic digestion for 2-20 hours. Denaturing conditions and digestion times yielding high production efficiency varied markedly among isoforms and specimens, indicating the importance of specific optimization. Each UGT isoform was quantified using the methods found to be optimal. The expression of 10 (1A1, 1A3, 1A4, 1A6, 1A9, 2B4, 2B7, 2B10, 2B15, and 2B17), 6 (1A1, 1A3, 1A4, 1A10, 2B7, and 2B17), and 3 (1A6, 1A9, and 2B7) isoforms was detected in human liver, intestinal, and kidney microsomes, respectively, and levels were reproducible using multiple protocols. All isoforms were quantified in rhUGTs. Determining the levels of UGTs in human tissue specimens and those in rhUGTs is important for estimating the contribution of glucuronidation to body clearance based on in vitro-in vivo extrapolation.


Subject(s)
Chromatography, High Pressure Liquid/methods , Glucuronosyltransferase/metabolism , Microsomes/enzymology , Peptide Fragments/analysis , Tandem Mass Spectrometry/methods , Calibration , Glucuronosyltransferase/genetics , Humans , Intestines/enzymology , Isoenzymes , Kidney/enzymology , Liver/enzymology , Protein Denaturation , Reproducibility of Results
3.
Hypertens Pregnancy ; 33(1): 93-101, 2014 Feb.
Article in English | MEDLINE | ID: mdl-24131296

ABSTRACT

OBJECTIVE: To assess nicardipine safety for fetuses and neonates. METHODS: Nicardipine was measured in maternal plasma (MP), umbilical cord arterial (UaP) and venous (UvP) plasma and breast milk (BrM) of 18 women with severe preeclampsia. RESULTS: Nicardipine was infused for a mean 11.9 ± 10.5 days before and 4.6 ± 1.6 days after delivery. Nicardipine dose and MP concentration were linearly correlated, as were MP with UaP, UvP, and BrM concentrations. The BrM/MP ratio was 0.06 to 0.30. The mean relative infant dose was 0.082%. CONCLUSION: Nicardipine is safe for fetuses and neonates due to its low levels of placental transfer and disposition in BrM.


Subject(s)
Antihypertensive Agents/pharmacokinetics , Milk, Human/chemistry , Nicardipine/pharmacokinetics , Placenta/metabolism , Pre-Eclampsia/drug therapy , Adult , Antihypertensive Agents/blood , Antihypertensive Agents/therapeutic use , Female , Fetal Blood/chemistry , Humans , Infant, Newborn , Nicardipine/blood , Nicardipine/therapeutic use , Pregnancy
4.
Mol Pharm ; 10(5): 1783-94, 2013 May 06.
Article in English | MEDLINE | ID: mdl-23560393

ABSTRACT

Mirabegron, a weak-basic compound, is a potent and selective ß3-adrenoceptor agonist for the treatment of overactive bladder. Mirabegron extended release formulation shows dose-dependent oral bioavailability in humans, which is likely attributable to saturation of intestinal efflux abilities leading to higher absorption with higher doses. This study evaluated the membrane permeability of mirabegron and investigated the involvement of human intestinal transport proteins in the membrane permeation of mirabegron. Transcellular transport and cellular/vesicular uptake assays were performed using Caco-2 cells and/or human intestinal efflux (P-glycoprotein [P-gp], breast cancer resistance protein [BCRP], and multidrug resistance associated protein 2 [MRP2]) and influx (peptide transporter 1 [PEPT1], OATP1A2, and OATP2B1) transporter-expressing cells, vesicles, or Xenopus laevis oocytes. The absorptive permeability coefficients of mirabegron in Caco-2 cells (1.68-1.83 × 10(-6) cm/s) at the apical and basal pH of 6.5 and 7.4, respectively, were slightly higher than those of nadolol (0.97-1.41 × 10(-6) cm/s), a low permeability reference standard, but lower than those of metoprolol and propranolol (both ranged from 8.49 to 11.6 × 10(-6) cm/s), low/high permeability boundary reference standards. Increasing buffer pH at the apical side from 5.5 to 8.0 gradually increased the absorptive permeation of mirabegron from 0.226 to 1.66 × 10(-6) cm/s, but was still less than the value in the opposite direction (11.0-14.2 × 10(-6) cm/s). The time- and concentration-dependent transport of mirabegron was observed in P-gp-expressing cells and OATP1A2-expressing oocytes with apparent Km values of 294 and 8.59 µM, respectively. In contrast, no clear BCRP-, MRP2-, PEPT1-, or OATP2B1-mediated uptake of mirabegron was observed in their expressing vesicles or cells. These findings suggest that mirabegron has low-to-moderate membrane permeability and P-gp is likely to be involved in its efflux into the lumen in the intestinal absorption process. The results also suggest that mirabegron could possibly be transported by intestinal influx transporters as well as simple diffusion.


Subject(s)
Acetanilides/pharmacokinetics , Adrenergic beta-3 Receptor Agonists/pharmacokinetics , Thiazoles/pharmacokinetics , ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism , ATP Binding Cassette Transporter, Subfamily G, Member 2 , ATP-Binding Cassette Transporters/metabolism , Animals , Biological Availability , Biological Transport, Active , Caco-2 Cells , Cell Membrane Permeability , Female , HEK293 Cells , Humans , Hydrogen-Ion Concentration , Intestinal Absorption/physiology , LLC-PK1 Cells , Neoplasm Proteins/metabolism , Oocytes/metabolism , Organic Anion Transporters/metabolism , Peptide Transporter 1 , Recombinant Proteins/metabolism , Swine , Symporters/metabolism , Urinary Bladder, Overactive/drug therapy , Xenopus laevis
5.
Xenobiotica ; 43(6): 534-47, 2013 Jun.
Article in English | MEDLINE | ID: mdl-23167531

ABSTRACT

1. The absorption, metabolism and excretion of darexaban (YM150), a novel oral direct factor Xa inhibitor, were investigated after a single oral administration of [(14)C]darexaban maleate at a dose of 60 mg in healthy male human subjects. 2. [(14)C]Darexaban was rapidly absorbed, with both blood and plasma concentrations peaking at approximately 0.75 h post-dose. Plasma concentrations of darexaban glucuronide (M1), the pharmacological activity of which is equipotent to darexaban in vitro, also peaked at approximately 0.75 h. 3. Similar amounts of dosed radioactivity were excreted via faeces (51.9%) and urine (46.4%) by 168 h post-dose, suggesting that at least approximately half of the administered dose is absorbed from the gastrointestinal tract. 4. M1 was the major drug-related component in plasma and urine, accounting for up to 95.8% of radioactivity in plasma. The N-oxides of M1, a mixture of two diastereomers designated as M2 and M3, were also present in plasma and urine, accounting for up to 13.2% of radioactivity in plasma. In faeces, darexaban was the major drug-related component, and N-demethyl darexaban (M5) was detected as a minor metabolite. 5. These findings suggested that, following oral administration of darexaban in humans, M1 is quickly formed during first-pass metabolism via UDP-glucuronosyltransferases, exerting its pharmacological activity in blood before being excreted into urine and faeces.


Subject(s)
Azepines/metabolism , Azepines/pharmacokinetics , Benzamides/metabolism , Benzamides/pharmacokinetics , Enzyme Inhibitors/pharmacology , Factor Xa Inhibitors , Absorption , Administration, Oral , Adult , Azepines/administration & dosage , Azepines/chemistry , Benzamides/administration & dosage , Benzamides/chemistry , Chromatography, High Pressure Liquid , Enzyme Inhibitors/administration & dosage , Enzyme Inhibitors/metabolism , Enzyme Inhibitors/pharmacokinetics , Factor Xa/metabolism , Humans , Male , Metabolomics , Reference Standards , Time Factors , Young Adult
6.
Xenobiotica ; 42(12): 1187-96, 2012 Dec.
Article in English | MEDLINE | ID: mdl-22834478

ABSTRACT

The potential for mirabegron, a ß(3)-adrenoceptor agonist for the treatment of overactive bladder, to cause drug-drug interactions via inhibition or induction of cytochrome P450 (CYP) enzymes was investigated in vitro. Mirabegron was shown to be a time-dependent inhibitor of CYP2D6 in the presence of NADPH as the IC(50) value in human liver microsomes decreased from 13 to 4.3 µM after 30-min pre-incubation. Further evaluation indicated that mirabegron may act partly as an irreversible or quasi-irreversible metabolism-dependent inhibitor of CYP2D6. Therefore, the potential of mirabegron to inhibit the metabolism of CYP2D6 substrates in vivo cannot be excluded. Mirabegron was predicted not to cause clinically significant metabolic drug-drug interactions via inhibition of CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2E1, or CYP3A4/5 because the IC(50) values for these enzymes both with and without pre-incubation were >100 µM (370 times maximum human plasma concentration [C(max)]). Whereas positive controls (100 µM omeprazole and 10 µM rifampin) caused the anticipated CYP induction, the highest concentration of mirabegron (10 µM; 37 times plasma C(max)) had minimal effect on CYP1A2 and CYP3A4/5 activity, and CYP1A2 and CYP3A4 mRNA levels in freshly isolated human hepatocytes, suggesting that mirabegron is not an inducer of these enzymes.


Subject(s)
Acetanilides/pharmacology , Adrenergic beta-3 Receptor Agonists/pharmacology , Cytochrome P-450 Enzyme Inhibitors , Cytochrome P-450 Enzyme System/biosynthesis , Enzyme Inhibitors/pharmacology , Thiazoles/pharmacology , Acetanilides/chemistry , Adrenergic beta-3 Receptor Agonists/chemistry , Cells, Cultured , Cytochrome P-450 Enzyme System/genetics , Enzyme Induction/drug effects , Enzyme Inhibitors/chemistry , Gene Expression Regulation, Enzymologic/drug effects , Hepatocytes/drug effects , Hepatocytes/enzymology , High-Throughput Screening Assays , Humans , Male , Microsomes, Liver/drug effects , Microsomes, Liver/enzymology , Middle Aged , NADP/metabolism , RNA, Messenger/genetics , RNA, Messenger/metabolism , Recombinant Proteins/antagonists & inhibitors , Recombinant Proteins/metabolism , Thiazoles/chemistry , Time Factors
7.
Xenobiotica ; 42(10): 957-67, 2012 Oct.
Article in English | MEDLINE | ID: mdl-22509825

ABSTRACT

1. Human cytochrome P450 (CYP) enzymes and esterases involved in the metabolism of mirabegron, a potent and selective human ß(3)-adrenoceptor agonist intended for the treatment of overactive bladder, were identified in in vitro studies. 2. Incubations of mirabegron with recombinant human CYP enzymes showed significant metabolism of mirabegron by CYP2D6 and CYP3A4 only. Correlation analyses showed a significant correlation between mirabegron metabolism and testosterone 6ß-hydroxylation (CYP3A4/5 marker activity). In inhibition studies using antiserum against CYP3A4, a strong inhibition (at maximum 80% inhibition) of the metabolism of mirabegron was observed, whereas the inhibitory effects of monoclonal antibodies against CYP2D6 were small (at maximum 10% inhibition). These findings suggest that CYP3A4 is the primary CYP enzyme responsible for in vitro oxidative metabolism of mirabegron, with a minor role of CYP2D6. 3. Mirabegron hydrolysis was catalyzed in human blood, plasma and butyrylcholinesterase (BChE) solution, but not in human liver microsomes, intestinal microsomes, liver S9, intestinal S9 and recombinant acetylcholinesterase solution. K(m) values of mirabegron hydrolysis in human blood, plasma and BChE solution were all similar (13.4-15.2 µM). The inhibition profiles in human blood and plasma were also similar to those in BChE solution, suggesting that mirabegron hydrolysis is catalyzed by BChE.


Subject(s)
Acetanilides/metabolism , Adrenergic beta-3 Receptor Agonists/metabolism , Cytochrome P-450 Enzyme System/metabolism , Esterases/metabolism , Receptors, Adrenergic, beta-3/metabolism , Thiazoles/metabolism , Acetanilides/blood , Acetanilides/chemistry , Acetylcholinesterase/metabolism , Adrenergic beta-3 Receptor Agonists/blood , Adrenergic beta-3 Receptor Agonists/chemistry , Antibodies, Monoclonal/pharmacology , Butyrylcholinesterase/metabolism , Cytochrome P-450 CYP2D6/metabolism , Cytochrome P-450 CYP2D6 Inhibitors , Cytochrome P-450 CYP3A/metabolism , Cytochrome P-450 CYP3A Inhibitors , Cytochrome P-450 Enzyme Inhibitors , DNA, Complementary/genetics , Esterases/antagonists & inhibitors , Female , Humans , Hydrolysis/drug effects , Immune Sera/metabolism , Isoenzymes/antagonists & inhibitors , Isoenzymes/metabolism , Kinetics , Liver/drug effects , Liver/metabolism , Male , Microsomes, Liver/drug effects , Microsomes, Liver/enzymology , Oxygenases/metabolism , Recombinant Proteins/metabolism , Solutions , Thiazoles/blood , Thiazoles/chemistry
8.
Drug Metab Dispos ; 40(7): 1389-96, 2012 Jul.
Article in English | MEDLINE | ID: mdl-22504157

ABSTRACT

The aims of this study were to develop a robust method for simultaneous quantification of carboxylesterases (CESs) 1 and 2 and to quantify those absolute protein levels in human liver tissue fractions. Unique peptide fragments of CES1 and CES2 in tryptically digested human liver microsomes (HLMs) and cytosol (HLC) were simultaneously quantified by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) using corresponding stable isotope-labeled peptides as internal standards. Bovine serum albumin was used as a blank matrix for the calibration curve samples. Our procedure showed good digestion efficiency, sensitivity, linearity of calibration curve, and reproducibility. The protein levels of CES1 and CES2 in 16 individual HLMs varied 4.7-fold (171-801 pmol/mg) and 3.5-fold (16.3-57.2 pmol/mg), respectively, that are approximately 10 times higher than the expression levels in HLC. The CES1/CES2 level ratio varied substantially from 3.0 to 25, and the correlation between the protein levels of CES1 and CES2 was negative, indicating significant interindividual variability and independence in their expression levels. CES1 levels significantly correlated with hydrolysis of the CES1 substrates, clopidogrel (5 µM) and oxybutynin (10 µM), whereas CES2 levels correlated strongly with hydrolysis of the CES2 substrate, irinotecan (1 µM), indicating that quantified protein levels are highly reliable. This is the first report to demonstrate the absolute protein levels of CESs quantified by LC-MS/MS.


Subject(s)
Carboxylic Ester Hydrolases/chemistry , Carboxylic Ester Hydrolases/metabolism , Chromatography, Liquid/methods , Liver/metabolism , Microsomes, Liver/metabolism , Tandem Mass Spectrometry/methods , Amino Acid Sequence , Animals , Calibration , Cattle , Cytosol/metabolism , Humans , Hydrolysis , Isotope Labeling/methods , Molecular Sequence Data , Peptide Fragments/chemistry , Peptide Fragments/metabolism , Reproducibility of Results , Serum Albumin, Bovine/chemistry , Serum Albumin, Bovine/metabolism
9.
Biol Pharm Bull ; 35(3): 413-21, 2012.
Article in English | MEDLINE | ID: mdl-22382330

ABSTRACT

Darexaban maleate is a novel oral direct factor Xa inhibitor. Darexaban glucuronide (YM-222714) was the major component in plasma after oral administration of darexaban to humans and is the pharmacologically active metabolite. Additionally, YM-222714 N-oxides were detected as minor metabolites in human plasma and urine. It is possible that YM-222714 N-oxides are formed by the N-oxidation of YM-222714 and/or the glucuronidation of darexaban N-oxides (YM-542845) in vivo. The former reaction is the pharmacological inactivation process. In this study, we identified the human enzymes responsible for YM-222714 N-oxidation and the uridine 5'-diphosphate (UDP)-glucuronosyltransferase (UGT) isoforms involved in YM-542845 glucuronidation in vitro. YM-222714 N-oxidation activity was detected in human liver microsomes (HLM), but not in human intestinal microsomes. In HLM, YM-222714 N-oxidation activities were significantly correlated with flavin-containing monooxygenase (FMO) marker enzyme activities (p<0.001) and inhibited by methimazole, a typical inhibitor of FMOs. Recombinant human FMO3 and FMO1 were capable of efficiently catalyzing YM-222714 N-oxidation, but not FMO5 or any recombinant human cytochrome P450 (CYP) isoforms. Considering the mRNA expression levels of FMO isoforms in human liver, these results strongly suggest that YM-222714 N-oxidation in HLM is mainly catalyzed by FMO3. In HLM, YM-542845 glucuronidation was strongly inhibited by typical substrates for UGT1A8, UGT1A9, and UGT1A10. Recombinant human UGT1A7, UGT1A8, UGT1A9, and UGT1A10 were capable of catalyzing YM-542845 glucuronidation, and UGT1A9 exhibited the highest intrinsic clearance. Considered together with the expression levels of UGT isoforms in human liver, these results strongly suggest that YM-542845 glucuronidation in HLM is mainly catalyzed by UGT1A9.


Subject(s)
Azepines/metabolism , Benzamides/metabolism , Glucuronides/metabolism , Glucuronosyltransferase/metabolism , Oxygenases/metabolism , Cytochrome P-450 Enzyme System/metabolism , Factor Xa Inhibitors , Humans , Microsomes, Liver/metabolism , Oxidation-Reduction , Protein Isoforms/metabolism , Recombinant Proteins/metabolism
10.
Biopharm Drug Dispos ; 33(3): 160-9, 2012 Apr.
Article in English | MEDLINE | ID: mdl-22374735

ABSTRACT

YM155 monobromide is a novel small-molecule survivin suppressant. The pharmacokinetics, distribution and excretion of YM155/[14C]YM155 were investigated using males and pregnant or lactating female rats after a single intravenous bolus administration. For the 0.1, 0.3 and 1 mg/kg YM155 doses given to male rats, increases in area under the plasma concentration-time curves were approximately proportional to the increase in the dose level. After administering [14C]YM155, radioactivity concentrations in the kidney and liver were highest among the tissues in both male and pregnant rats: e.g. 14.8- and 5.24-fold, respectively, and higher than in plasma at 0.1 h after dosing to male rats. The YM155 concentrations in the brain were lowest: 25-fold lower than in plasma. The transfer of radioactivity into fetuses was low (about 2-fold lower than in plasma). In lactating rats, the radioactivity was transferred into milk at a level 8- to 21-fold higher than for plasma. Radioactivity was primarily excreted in feces (64.0%) and urine (35.2%). The fecal excretion was considered to have occurred mainly by biliary excretion and partly by secretion across the gastrointestinal membrane from the blood to the lumen.


Subject(s)
Antineoplastic Agents/pharmacokinetics , Imidazoles/pharmacokinetics , Lactation/metabolism , Naphthoquinones/pharmacokinetics , Pregnancy/metabolism , Animals , Antineoplastic Agents/blood , Antineoplastic Agents/urine , Bile/chemistry , Blood Proteins/metabolism , Feces/chemistry , Female , Imidazoles/blood , Imidazoles/urine , Male , Maternal-Fetal Exchange , Microtubule-Associated Proteins/antagonists & inhibitors , Naphthoquinones/blood , Naphthoquinones/urine , Placenta/metabolism , Rats , Rats, Sprague-Dawley , Survivin , Tissue Distribution
11.
Xenobiotica ; 42(9): 823-9, 2012 Sep.
Article in English | MEDLINE | ID: mdl-22435749

ABSTRACT

The aims of this study were to quantify absolute protein levels of uridine 5'-diphosphate-glucuronosyltransferases (UGTs) 1A1 and 2B7 in human liver microsomes (HLMs) and to investigate their correlation with marker activities. A quantification method for UGT1A1 and UGT2B7 in HLMs was developed. Unique tryptic peptides of UGT1A1 and UGT2B7 in tryptically digested HLMs were simultaneously quantified by liquid chromatography (LC) equipped with tandem mass spectrometry (MS) using corresponding stable isotope-labelled peptides as internal standards. Bovine serum albumin was used as a blank matrix for calibration curve samples. Our procedure had good digestion efficiency, sensitivity, calibration curve linearity, and reproducibility of digestion to quantification. In 16 individual HLMs, the protein levels of UGT1A1 and UGT2B7 ranged from 6.50 to 44.6 pmol/mg and 4.45 to 18.2 pmol/mg, respectively. Estradiol 3ß-glucuronidation correlated strongly with the UGT1A1 level, indicating its high reliability as a reaction marker. Both morphine 3-O- and 6-O-glucuronidation significantly correlated with UGT2B7 level. However, the intercept of the linear regression clearly indicates that morphine glucuronidation was mediated by other UGT isoforms in addition to UGT2B7.


Subject(s)
Glucuronosyltransferase/analysis , Microsomes, Liver/enzymology , Biomarkers/analysis , Blotting, Western , Chromatography, Liquid , Electrophoresis, Polyacrylamide Gel , Estradiol/analogs & derivatives , Estradiol/metabolism , Humans , Isotope Labeling , Tandem Mass Spectrometry
12.
Drug Metab Dispos ; 40(5): 902-6, 2012 May.
Article in English | MEDLINE | ID: mdl-22293119

ABSTRACT

The aim of this study was to conclusively determine the enzyme responsible for the hydrolysis of oxybutynin in human liver. Hydrolysis in human liver microsomes (HLMs) and human liver cytosol (HLC) followed Michaelis-Menten kinetics with similar K(m) values. In recombinant human carboxylesterase (CES)-expressing microsomes, CES1 was much more efficient than CES2 and yielded a K(m) value more comparable with that found in HLMs or HLC than did CES2. A correlation analysis using a set of individual HLMs, in which both CESs acted independently showed that the hydrolysis rate of oxybutynin, correlated significantly with a CES1 marker reaction, clopidogrel hydrolysis, but not with a CES2 marker reaction, irinotecan (CPT-11) hydrolysis. Chemical inhibition studies using bis-(p-nitrophenyl) phosphate, clopidogrel, nordihydroguaiaretic acid, procainamide, physostigmine, and loperamide revealed that the effects of these compounds in HLMs, HLC, and recombinant CES1-expressing microsomes were similar, whereas those in CES2-expressing microsomes were clearly different. These results strongly suggest that CES1, rather than CES2, is the principal enzyme responsible for the hydrolysis of oxybutynin in human liver.


Subject(s)
Carboxylesterase/metabolism , Carboxylic Ester Hydrolases/metabolism , Liver/enzymology , Mandelic Acids/pharmacokinetics , Muscarinic Antagonists/pharmacokinetics , Biotransformation , Carboxylesterase/antagonists & inhibitors , Carboxylesterase/genetics , Carboxylic Ester Hydrolases/antagonists & inhibitors , Carboxylic Ester Hydrolases/genetics , Chromatography, High Pressure Liquid , Cytosol/enzymology , Cytosol/metabolism , Enzyme Inhibitors/pharmacology , Humans , Hydrolysis , In Vitro Techniques , Liver/metabolism , Mandelic Acids/chemistry , Microsomes, Liver/enzymology , Microsomes, Liver/metabolism , Molecular Structure , Muscarinic Antagonists/chemistry , Tandem Mass Spectrometry
13.
Drug Metab Dispos ; 40(4): 815-24, 2012 Apr.
Article in English | MEDLINE | ID: mdl-22269146

ABSTRACT

The mass balance and metabolite profiles of 2-(2-amino-1,3-thiazol-4-yl)-N-[4-(2-{[(2R)-2-hydroxy-2-phenylethyl]amino}ethyl)[U-(14)C]phenyl]acetamide ([(14)C]mirabegron, YM178), a ß(3)-adrenoceptor agonist for the treatment of overactive bladder, were characterized in four young, healthy, fasted male subjects after a single oral dose of [(14)C]mirabegron (160 mg, 1.85 MBq) in a solution. [(14)C]Mirabegron was rapidly absorbed with a plasma t(max) for mirabegron and total radioactivity of 1.0 and 2.3 h postdose, respectively. Unchanged mirabegron was the most abundant component of radioactivity, accounting for approximately 22% of circulating radioactivity in plasma. Mean recovery in urine and feces amounted to 55 and 34%, respectively. No radioactivity was detected in expired air. The main component of radioactivity in urine was unchanged mirabegron, which accounted for 45% of the excreted radioactivity. A total of 10 metabolites were found in urine. On the basis of the metabolites found in urine, major primary metabolic reactions of mirabegron were estimated to be amide hydrolysis (M5, M16, and M17), accounting for 48% of the identified metabolites in urine, followed by glucuronidation (M11, M12, M13, and M14) and N-dealkylation or oxidation of the secondary amine (M8, M9, and M15), accounting for 34 and 18% of the identified metabolites, respectively. In feces, the radioactivity was recovered almost entirely as the unchanged form. Eight of the metabolites characterized in urine were also observed in plasma. These findings indicate that mirabegron, administered as a solution, is rapidly absorbed after oral administration, circulates in plasma as the unchanged form and metabolites, and is recovered in urine and feces mainly as the unchanged form.


Subject(s)
Acetanilides/pharmacokinetics , Adrenergic beta-3 Receptor Agonists/pharmacokinetics , Receptors, Adrenergic, beta-3/metabolism , Thiazoles/pharmacokinetics , Absorption , Acetanilides/administration & dosage , Acetanilides/blood , Acetanilides/metabolism , Acetanilides/urine , Administration, Oral , Adrenergic beta-3 Receptor Agonists/administration & dosage , Adrenergic beta-3 Receptor Agonists/blood , Adrenergic beta-3 Receptor Agonists/metabolism , Adrenergic beta-3 Receptor Agonists/urine , Adult , Carbon Radioisotopes , Chromatography, High Pressure Liquid , Dose-Response Relationship, Drug , Feces/chemistry , Humans , Male , Mass Spectrometry , Metabolic Clearance Rate , Molecular Structure , Thiazoles/administration & dosage , Thiazoles/blood , Thiazoles/metabolism , Thiazoles/urine , Young Adult
14.
Drug Metab Dispos ; 40(2): 276-82, 2012 Feb.
Article in English | MEDLINE | ID: mdl-22031623

ABSTRACT

Darexaban maleate is a novel oral direct factor Xa inhibitor, which is under development for the prevention of venous thromboembolism. Darexaban glucuronide was the major component in plasma after oral administration of darexaban to humans and is the pharmacologically active metabolite. In this study, we identified UDP-glucuronosyltransferases (UGTs) responsible for darexaban glucuronidation in human liver microsomes (HLM) and human intestinal microsomes (HIM). In HLM, the K(m) value for darexaban glucuronidation was >250 µM. In HIM, the reaction followed substrate inhibition kinetics, with a K(m) value of 27.3 µM. Among recombinant human UGTs, UGT1A9 showed the highest intrinsic clearance for darexaban glucuronidation, followed by UGT1A8, -1A10, and -1A7. All other UGT isoforms were inactive toward darexaban. The K(m) value of recombinant UGT1A10 for darexaban glucuronidation (34.2 µM) was comparable to that of HIM. Inhibition studies using typical UGT substrates suggested that darexaban glucuronidation in both HLM and HIM was mainly catalyzed by UGT1A8, -1A9, and -1A10. Fatty acid-free bovine serum albumin (2%) decreased the unbound K(m) for darexaban glucuronidation from 216 to 17.6 µM in HLM and from 35.5 to 18.3 µM in recombinant UGT1A9. Recent studies indicated that the mRNA expression level of UGT1A9 is extremely high among UGT1A7, -1A8, -1A9, and -1A10 in human liver, whereas that of UGT1A10 is highest in the intestine. Thus, the present results strongly suggest that darexaban glucuronidation is mainly catalyzed by UGT1A9 and UGT1A10 in human liver and intestine, respectively. In addition, UGT1A7, -1A8, and -1A9 play a minor role in human intestine.


Subject(s)
Azepines/metabolism , Benzamides/metabolism , Glucuronides/metabolism , Glucuronosyltransferase/metabolism , Jejunum/enzymology , Liver/enzymology , Microsomes/enzymology , Anticoagulants/metabolism , Drugs, Investigational/metabolism , Enzyme Inhibitors/pharmacology , Factor Xa Inhibitors , Glucuronosyltransferase/antagonists & inhibitors , Glucuronosyltransferase/genetics , Humans , Isoenzymes/antagonists & inhibitors , Isoenzymes/genetics , Isoenzymes/metabolism , Jejunum/drug effects , Kinetics , Liver/drug effects , Microsomes/drug effects , Microsomes, Liver/drug effects , Microsomes, Liver/enzymology , Organ Specificity , Recombinant Proteins/antagonists & inhibitors , Recombinant Proteins/metabolism , Substrate Specificity , UDP-Glucuronosyltransferase 1A9
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