Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.6.3.44 (P-glycoprotein)
13,344 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have developed and validated a sensitive and selective method for the quantitative determination of the P-glycoprotein inhibitor zosuquidar (LY335979) in human and murine plasma using only 50 microl sample volumes. Sample pretreatment involved liquid-liquid extraction with tert-butyl methyl ether. Zosuquidar and the internal standard chlorpromazine were separated using a narrow bore column (2.1 mm x 150 mm) packed with 3.5 microm symmetry C(18) material. The mobile phase consisted of 38% (v/v) acetonitrile in 50mM ammonium acetate buffer pH 3.8 containing 0.005 M 1-octyl sulfonic acid and was delivered at 0.2 ml/min. Detection was performed with a fluorescence detector set at an excitation wavelength of 260 nm and an emission wavelength of 460 nm. The calibration curve was prepared in blank human plasma and was linear over the dynamic range (10-1000 ng/ml). The lower limit of quantitation was 20 ng/ml. The validation results showed that the assay was selective and reproducible. Within the range of the calibration curve the accuracy was close to 100% and within-day and between-day precision were within the generally accepted 15% range. This method was applied to study the pharmacokinetics of i.v. administered zosuquidar in mice. The sensitivity of the assay was sufficient to determine the drug concentration in plasma samples obtained up to 24 h after administration.
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PMID:Bioanalysis of zosuquidar trihydrochloride (LY335979) in small volumes of human and murine plasma by ion-pairing reversed-phase high-performance liquid chromatography. 1463 Mar 60

A method coupled with microdialysis technique and liquid chromatography was applied in the continuous and concurrent in vivo monitoring of extracellular hesperidin in the blood and bile of anaesthetized rats. Hesperidin was intravenously administered via the femoral vein. Sampling was achieved using two microdialysis probes, which were implanted into the jugular vein and into the bile duct. Dialysates of blood and bile were both directly injected onto the liquid chromatographic system, so no further clean-up procedures were required. Separation was performed using a reversed phase ODS-2 microbore column 150 mm x 1 mm i.d., particle size 5 microm with mobile phase of acetonitrile-0.1M ammonium acetate (30:70, v/v) at flow-rate of 0.05 ml/min. The UV detection for hesperidin was set at a wavelength of 283 nm. This method was used to determine the pharmacokinetics of hesperidin and its interaction in the presence of cyclosporin A, which is a P-glycoprotein modulator. The results indicate that the curve of area under the concentration versus time (AUC) for hesperidin in bile was significantly greater than that for hesperidin in blood at the dose of 30 mg/kg. The blood-to-bile distribution ratio (k = AUC(bile)/AUC(blood)) was 8.9 +/- 2.5 for hesperidin at 30 mg/kg. Following cyclosporin A treatment, the distribution ratio was reduced to 3.2 +/- 0.6. In conclusion, hesperidin goes through hepatobiliary elimination against the concentration gradient from blood to bile, and this hepatobiliary excretion of hesperidin may be regulated by the P-glycoprotein.
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PMID:Determination of extracellular hesperidin in blood and bile of anaesthetized rats by microdialysis with high-performance liquid chromatography: a pharmacokinetic application. 1517 25

A simple, rapid, sensitive and specific reversed-phase high performance liquid chromatographic (RP-HPLC) method involving ultraviolet detection (lambda = 210 nm) was developed for analysis of indinavir along with propranolol in samples obtained from ex vivo intestinal permeability studies. Chromatography was carried out on C-18 column with mobile phase comprising of phosphate buffer-acetonitrile (68:32, v/v) pumped at flow rate of 1 ml/min. The proposed method has a short run time of 12 min and involves a simple sample preparation for the purpose of reducing permeability model artifacts and to concentrate the samples. Fluorescein was used as internal standard. The proposed method has been validated with regard to specificity, detection limit, recovery, accuracy and precision. For both the drugs, method was found to be selective, linear (R(2) approximately 0.999), accurate (recovery = 100-105%) and precise (<3% R.S.D.) in the range of 2-20 microg/ml. The limit-of-detection and limit-of-quantification of the method were 40 ng/ml and 100 ng/ml for indinavir, and 30 and 80 ng/ml for propranolol, respectively. Indinavir, a widely prescribed HIV protease inhibitor, suffer from bioavailability problems where involvement of P-glycoprotein mediated drug efflux may play a significant role. The proposed method was successfully applied for intestinal permeability of indinavir to estimate the contribution of P-glycoprotein in limiting its oral bioavailability. The advantage of the developed method lies in the simultaneous determination of propranolol, a passive integrity marker, routinely employed in permeability studies and its selectivity in presence of various P-gp modulators and permeability markers.
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PMID:Reversed-phase liquid chromatography with ultraviolet detection for simultaneous quantitation of indinavir and propranolol from ex-vivo rat intestinal permeability studies. 1517 39

Extracts of bitter melon, soybean, dokudami and welsh onion by 40% methanol increased the accumulation of rhodamine-123 by Caco-2 cells, suggesting that these extracts inhibited P-glycoprotein (P-gp). The extract of bitter melon was separated in a tC18 cartridge column and the eluate from 80% acetonitrile most markedly increased the [(3)H]-daunomycin accumulation by Caco-2 cells. The inhibitory compounds in the bitter melon fraction were isolated by HPLC with Pegasil C4 and Pegasil ODS columns. The HPLC fraction having the highest activity was analyzed by (1)H-NMR and FAB-MS, and the active compound was identified as 1-monopalmitin. The inhibitory activities of 1-monopalmitin and its related compounds suggested that the inhibition of P-gp activity was not dependent on the degree of unsaturation of fatty acid in the monoglyceride, but on the chain length. It was also suggested that the monoglyceride structure played an important role in the inhibition of P-gp activity. Monoglycerides could therefore alter the pharmacokinetics of drugs by inhibiting the P-gp-mediated efflux.
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PMID:Inhibitory effect of a bitter melon extract on the P-glycoprotein activity in intestinal Caco-2 cells. 1535 76

A liquid chromatographic/tandem mass spectrometric (LC/MS/MS) method for the determination of the P-glycoprotein and breast cancer resistance protein inhibitor Elacridar in human and dog plasma is described. The internal standard was stable isotopically labelled Elacridar. Sample pretreatment involved liquid-liquid extraction with tert-butyl methyl ether. Analysis of Elacridar and internal standard was performed by reversed-phase LC on a basic stable minibore analytical column with an eluent consisting of acetonitrile and aqueous ammonia. An API-2000 triple-quadrupole mass spectrometer with an electrospray ion source was used in the positive-ion multiple reaction monitoring mode. The run time per sample was only 6 min. The method is sensitive and specific, with a dynamic range from 1 to 500 ng ml(-1) from 100 microl of human or dog plasma. The accuracy of the method was within 15% bias and the precision was lower than 15% for all tested concentration levels and in both matrices. The method is simple and the liquid-liquid extraction produces clean samples. This method was successfully applied to support the pharmacokinetics of a clinical trial in which orally applied Elacridar was used as a bioavailability enhancer.
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PMID:Quantitative analysis of the P-glycoprotein inhibitor Elacridar (GF120918) in human and dog plasma using liquid chromatography with tandem mass spectrometric detection. 1546 45

A simple, sensitive and specific reversed-phase high performance liquid chromatographic (RP-HPLC) assay for simultaneous determination of digoxin and permeability markers, in samples obtained from intestinal in situ single-pass perfusion studies, was developed and validated. Chromatography was carried on C-18 column with mobile phase comprising of acetate buffer (pH 3.0), acetonitrile and methanol in the ratio of 50:25:25 (v/v/v), was pumped at a flow rate of 0.5 ml/min and UV detection was employed at 220 nm. The average retention times for phenolred, propranolol, frusemide and digoxin were 9.1, 10.7, 12.9 and 15.3 min, respectively. The calibration curves were linear (R(2) > 0.998) in the range for each analyte. The method is specific and sensitive with limit of quantification of 25 ng/ml for digoxin and frusemide and 10 ng/ml for phenolred and propranolol. The method is accurate and precise with recoveries of digoxin in the range of 95.2 and 103.2% and relative standard deviation (R.S.D.) <5%. We found that this method was simple and reliable in permeability determination and to estimate the contribution of P-glycoprotein in limiting intestinal absorption.
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PMID:Simultaneous determination of digoxin and permeability markers in rat in situ intestinal perfusion samples by RP-HPLC. 1555 52

Rhodamine 123 (R123) is widely used to quantify P-glycoprotein (P-GP) functional efflux activity in vitro. We developed a rapid and specific high-performance liquid chromatography (HPLC) method to quantify Rhodamine 123 for use in experimental cell culture studies. The R123 standards (2.5-250 ng/mL) and quality controls (QCs) (5, 75, 200 ng/mL) were prepared in cell lysis buffer consisting of 0.75% Triton 100X and 0.2% sodium chloride. The mobile phase consisted of acetonitrile, 1.5 mM tetrabutyl ammonium bromide in 20mM sodium acetate buffer (pH 4.0) (50:20:30) delivered at a rate of 1.0 mL/min. Samples (50 microl) were injected onto a C(18) reversed-phase HPLC column with detection at 500 nm. Analyte retention times were 1.4 and 4.3 min for R123 and internal standard (R6G), respectively. Intra- and inter-day coefficients of variation were < or = 4.2%. Samples were stable for at least three freeze-thaw cycles at room temperature for 24 and 48 h. This method was used to evaluate the functional activity of P-glycoprotein in renal tubule cell models including human kidney (HK-2), Madin-Darby canine kidney (MDCK) and multi-drug resistance gene-transfected MDCK cells (MDR1-MDCK).
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PMID:Determination of Rhodamine 123 in cell lysate by HPLC with visible wavelength detection. 1563 47

To investigate the pharmacokinetics of unbound ranitidine in rat blood and bile, multiple microdialysis probes coupled to a liquid chromatographic system were developed. This study design was parallel in the following groups: the control-group of six rats received ranitidine alone (10 and 30 mg/kg, i.v.), the treated-group rats were co-administered with ranitidine and cyclosporine (P-glycoprotein (P-gp) inhibitor) or quinidine (both organic cation transport (OCT) and P-gp inhibitors) in six individual rats. Microdialysis probes were inserted into the jugular vein and the bile duct for blood and bile fluids sampling, respectively. Ranitidine in the dialysate was separated by a reversed-phase C18 column (Zorbax, 150 mm x 4.6 mm i.d.; 5 microm) maintained at ambient temperature. Samples were eluted with a mobile phase containing acetonitrile-methanol-tetrahydrofuran-20 mM K2HPO4 (pH 7.0) (24:20:10:946, v/v), and the flow rate of the mobile phase was 1 ml/min. The optimal UV detection for ranitidine was set at wavelength 315 nm. Between 20 and 30 min after drug administration (10 or 30mg/kg), the ranitidine reached the maximum concentration in the bile. The bile-to-blood distribution ratio (AUC(bile)/AUC(blood)) was 9.8 +/- 1.9 and 13.9 +/- 3.8 at the dosages of 10 and 30 mg/kg, respectively. These studies indicate that ranitidine undergoes hepatobiliary excretion which against concentration gradient from bile-to-blood. In addition, the AUC of ranitidine in bile decreased in the treatment of cyclosporine or quinidine, which suggests that the hepatobiliary excretion of ranitidine was partially regulated by P-glycoprotein or organic cation transporter.
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PMID:Measurement of unbound ranitidine in blood and bile of anesthetized rats using microdialysis coupled to liquid chromatography and its pharmacokinetic application. 1590 33

Genistein, the major isoflavone in soybeans, has been shown to have a wide range of effects. We used an HPLC-UV combined with microdialysis method to detect unbound genistein in rat blood, brain and bile. Genistein dialysates were eluted with a mobile phase containing acetonitrile-water (40:60, v/v, pH 3.5 adjusted by 0.1% acetic acid). Samples were separated using a phenyl (5 microm) column maintained at ambient temperature. The UV detector wavelength was set at 259 nm. The flow rate was 1.0 m/min. The limit of quantitation for genistein was 50 ng/ml. The in vitro recoveries of genistein were 31 +/- 1, 13 +/- 1 and 59 +/- 4% in microdialysis probes of blood, brain and bile, respectively (n = 4). Inter- and intra-assay accuracy and precision of the analysis were less than 10% in the concentration ranges of 0.05-5.0 microg/ml. A small ratio of genistein penetrates the blood-brain barrier (BBB) and goes through hepatobiliary excretion after genistein administration (10 or 30 mg/kg, i.v.). The brain-to-blood (AUC(brain)/AUC(blood)) and bile-to-blood (AUC(bile)/AUC(blood)) distribution ratios were 0.04 +/- 0.01 and 1.85 +/- 0.42, respectively for the dosage of genistein 30 mg/kg. After co-administration of cyclosporine, a P-glycoprotein (P-gp) inhibitor, the distribution ratios of genistein in brain and bile were not significantly altered. These results suggest that the BBB penetration and hepatobiliary excretion of genistein may not regulated by P-gp.
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PMID:Concurrent measurement of unbound genistein in the blood, brain and bile of anesthetized rats using microdialysis and its pharmacokinetic application. 1590 36

A simple and reliable reversed-phase high-performance liquid chromatography method was developed and validated for the determination of DHP-014, a niguldipine analogue with potent P-glycoprotein inhibitory and negligible calcium channel blocking properties, in rat plasma. DHP-014 and niguldipine hydrochloride (the internal standard) were extracted from rat plasma by liquid extraction using hexane. DHP-014 was then separated by HPLC on a C18 column and quantified by ultraviolet detection at 238 nm. The mobile phase consisted of acetonitrile-aqueous 5 mM phosphate buffer (65:35, v/v) containing 0.4% (v/v) triethylamine adjusted to pH 7.0. The mean extraction efficiency of DHP-014 was 109.0 +/- 12.9, 97.7 +/- 8.0 and 102.9 +/- 7.5% for DHP-014 concentrations of 10, 50 and 100 nM, respectively (n = 5). The method was linear over the concentration range 2.5-200 nM with a regression coefficient of 0.998. The limit of detection of DHP-014 in rat plasma was 1.0 nM. The intra- and inter-day coefficients of variation for DHP-014 in rat plasma were 4.7-7.9 and 6.9-9.9%, respectively. The intra- and inter-day accuracy was 98.2-99.5 and 97.9-103%, respectively. The bioanalytical technique was used to determine DHP-014 in plasma samples in a pharmacokinetic study of DHP-014 administered to female Sprague-Dawley rats.
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PMID:A high-performance liquid chromatographic method for determination of the niguldipine analogue DHP-014. 1595 60


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