Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q3SYG4 (C18)
 23,707 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A rapid and validated liquid chromatography coupled to tandem mass spectrometric method (LC-MS-MS) has been developed and applied to pharmacokinetic and bioequivalence studies in 24 healthy male Korean volunteers. The procedure involves a liquid-liquid extraction of paroxetine (CAS 61869-08-7) and fluoxetine (internal standard, CAS 54910-89-3) with ether/methyl chloride (7:3, v/v) and separated by LC equipped with C18 column using acetonitrile: 5 mmol/L ammonium formate (4:3, v/v) as mobile phase. Detection is carried out on an API 2000 MS system by multiple reactions monitoring mode. The ionization was optimized using ESI(+) and selectivity was achieved by MS-MS analysis, mlz 330.0-->192.0 and m/ z 310-->148 for paroxetine and fluoxetine, respectively. The method has a total run time of 1.5 min and was linear over a working range of 0.05-20 ng/mL and the lower limit of quantification was 0.05 ng/ mL. No endogenous compounds were found to interfere with the analysis. The inter-day and intra-day accuracy was in the ranges of 102.69-107.79% and 102.07-109.57%, respectively and precision of inter-day and intra-day expressed as relative standard deviation were 1.86-9.99% and 1.52-6.28%, respectively. The validation of this method on linearity, specificity, accuracy, precision as well as applicability to pharmacokinetic and bioequivalence studies by analysis of blood samples taken up to 72 h after oral administration of 20 mg of paroxetine in 24 healthy volunteers were found to be good performance.
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PMID:Determination of paroxetine in plasma by liquid chromatography coupled to tandem mass spectrometry for pharmacokinetic and bioequivalence studies. 1780 58

A simple, fast, sensitive and selective solid-phase extraction-liquid chromatography-tandem mass spectrometry (SPE-LC-MS/MS) method for the quantitative analysis of ampicillin (CAS 69-53-4) in human plasma was developed using amoxicillin as internal standard, and sample extraction by solid-phase extraction (SPE). Extracts were separated by reversed-phase C18 with aqueous mobile phase (acetonitrile, 80:20, v/v) with 0.1% formic acid. The method was validated and successfully applied in a bioequivalence study of capsules 500 mg of ampicillin. Using a short running time of 2.5 min, the lower limit of quantification (LLOQ) for obtained ampicillin was 0.1 microg/ml for a plasma sample of 250 microl and a recovery of 94.38% +/- 4.05. Bioequivalence between the products was determined by calculating 90% confidence intervals (CI) for the ratio of Cmax, AUC0-t and AUC0-inf values for the test and reference products, which were within the 0.80-1.25 interval proposed by FDA and EMEA. It is concluded that the two formulations are bioequivalent in their rate and extent of absorption, and thus, may be used interchangeably.
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PMID:Determination of ampicillin in human plasma by solid-phase extraction-liquid chromatography-tandem mass spectrometry (SPE-LC-MS/MS) and its use in bioequivalence studies. 1841 23

A sensitive and selective high performance liquid chromatographic (HPLC) method was developed and validated for the rapid quantification of rivastigmine (CAS 123441-03-2) in micro quantity in rat plasma samples. The chromatographic separation was achieved with a reverse phase monomeric column C18 (4.6 x 250 mm, 5 microm) and the mobile phase consisted of acetonitrile and 20 mmol/L phosphate buffer pH 3.0 (25:75) with a flow rate of 1 mL/min. The effluents were measured by fluorimetric detection with excitation and emission wavelengths at 220 nm and 293 nm, respectively. The calibration curve was linear (r2 > 0.99) ranging from 25-3000 ng/mL and the lower limit of quantification was 25 ng/mL. The method was validated with excellent sensitivity, selectivity, accuracy, precision, recovery and stability. The method has been successfully applied in a pharmacokinetic study of rivastigmine in rats.
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PMID:Fluorimetric determination of rivastigmine in rat plasma by a reverse phase--high performance liquid chromatographic method. Application to a pharmacokinetic study. 1858 53

A high performance liquid chromatographic (HPLC) method for simultaneous determination of rosiglitazone, CAS 122320-73-4, RSG), cilostazol (CAS 73963-72-1, CLZ) and its active metabolite 3, 4-dehydro-cilostazol (DCLZ), using pioglitazone (PIO) as internal standard (IS), in rat plasma is described. The plasma was extracted with methyl t-butyl ether, the dry extract was reconstituted in mobile phase and the aliquot was injected. The eluent drugs were detected by UV at dual wavelength of 226 nm (RSG and DCLZ) and 257 nm (CLZ). The mobile phase consisting of acetonitrile:potassium di-hydrogen phosphate buffer (35:65 v/v) was used at the flow rate of 1.2 ml/min on a reverse phase C18 column. The absolute recovery was above 90% of all analytes over the concentration range of 25-2500 ng/ml for RSG and CLZ and 20-2000 ng/ ml for DCLZ. The relative standard deviation (RSD) of the inter-day and intra-day precision ranged from 2.8 to 8.4% and 0.9 to 5.9%, respectively. The method is simple, rapid, accurate and sensitive and was applied to pharmacokinetic studies.
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PMID:Validated high performance liquid chromatographic method for simultaneous determination of rosiglitazone, cilostazol, and 3,4-dehydro-cilostazol in rat plasma and its application to pharmacokinetics. 1867 71

A sensitive and selective high-performance liquid chromatographic-ultraviolet (HPLC-UV) method for the determination of mycophenolic acid (MPA, CAS 24280-93-1) in human plasma has been developed. Sample treatment was based on protein precipitation with a trichloroacetic acid-water (10:90, w/v) solution. The analytical determination was carried out by HPLC with ultraviolet detection at 254 nm. Chromatographic separation was achieved on a C18 column by isocratic elution with acetonitrile-water (pH 4.4) (50:50, v/v) at a flow rate of 1.0 mL/min. The method was linear in the concentration range of 0.2-50.0 microg/mL. The lower limit of quantification (LLOQ) was 0.2 microg/ mL. The intra-day and inter-day relative standard deviations across three validation runs over the entire concentration range were less than 7.05%. The accuracy determined at three concentrations (0.4, 5.0 and 20.0 microg/mL for MPA) was within +/- 10.0%. The method was successfully applied to the evaluation of the pharmacokinetic profile of MPA dispersible tablet in 20 healthy volunteers. The results showed that AUC, C(max) and T1/2 for the test and reference formulations were not significantly different (P > 0.05). The relative bioavailability was 96.42 +/- 15.5%.
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PMID:High-performance liquid chromatography method for the determination of mycophenolic acid in human plasma and application to a pharmacokinetic study of mycophenolic acid dispersible tablet. 1875 1

A sensitive liquid chromatography-tandem mass spectrometry (LC/MS/MS) method was developed and validated for the determination of trimetazidine (CAS 13171-25-0) in human plasma, using pseudoephedrine as internal standard (IS). Plasma samples were simply pretreated with methanol for deproteinization. The chromatographic separation was performed on a C18 column with a mobile phase of 3 mmol/L ammonium acetate solution-methanol (15:85, v/v) at a flow rate of 0.3 mL/min. The chromatographic separation was achieved in less than 3.2 min. The linearity was established over the concentration range of 1-100 ng/mL. Both intra- and inter-batch standard deviations were less than 9.5%. The method was successfully applied to study the relative bioavailability of trimetazidine hydrochloride tablets in healthy Chinese volunteers and the pharmacokinetic parameters of the reference and test tablets were compared.
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PMID:Liquid chromatography-tandem mass spectrometry method for the determination of trimetazidine in human plasma. 1897 71

A sensitive and selective liquid chromatographic--mass spectrometric (LC-MS) method for the determination of gliclazide (CAS 21187-98-4) in human plasma has been developed. Sample treatment was based on protein precipitation with acetonitrile. Analytical determination was carried out on a C18 column interfaced with a triple quadrupole mass spectrometer. Positive electrospray ionization was employed as the ionization source. The mobile phase was acetonitrile-water containing 10 mmol/l ammonium acetate, pH 3.5 adjusted with acetic acid (75:25) at the flow rate of 1.0 ml/min. Both the analyte and the internal standard glipizide (CAS 29094-61-9) were detected by use of selected ion monitoring mode. The method was linear in the concentration range of 0.025-2.5 microg/mL. The lower limit of quantification (LLOQ) was 0.025 microg/mL. The intra- and inter-day relative standard deviation across three validation runs over the entire concentration range was less than 9.8%. The accuracy determined at three concentrations (0.05, 0.2 and 1.5 microg/mL for gliclazide) was within +/- 10.11% in terms of relative error (RE). The method herein described was successfully applied for the evaluation of pharmacokinetic profiles of gliclazide sustained release tablets in 18 healthy volunteers. The results show that AUC, Tmax, Cmax and T1/2 between the test formulation and reference formulation have no significant difference (P > 0.05). Relative bioavailability is 96.7.4 +/- 12.9%.
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PMID:Liquid chromatography--mass spectrometry method for the determination of gliclazide in human plasma and application to a pharmacokinetic study of gliclazide sustained release tablets. 1920 37

A fast, specific, accurate, precise and reproducible high-performance liquid chromatography (HPLC) method with diode-array detector (DAD) was developed and validated for the determination of ketoprofen (CAS 22071-15-4) in human plasma using flubiprofen (CAS 5104-49-4) as an internal standard. The chromatographic separation was achieved on an onyx monolithic C18 (100 x 4.6 mm) analytical column with an isocratic mobile phase consisting of acetonitrile/potassium dihydrogen phosphate (KH2PO4) 0.01 M, (40:60, v/v) adjusted to pH 3.5. The flow was set at 5 ml x min(-1) and the wavelength at 254 nm. The total analysis time was less than 5 min. The ratio of peak area of analyte to internal standard was used for quantification. The limit of detection was defined as the ketoprofen concentration that produced a signal-to noise ratio greater than 3. The lower limit of quantification (LLOQ) was 10 ng x m(-1). At this level, the relative standard deviation (RSD) was lower than 13%. The calibration curve was linear over the concentration range 1-500 ng x ml(-1) with a minimum detectable limit of 10 ng x ml(-1). The coefficients of variation for the inter-day and intra-day assay were found to be less than 11%. The present method was successfully applied to the routine analysis of human plasma samples collected from healthy volunteers after dermal application of two topical formulations containing ketoprofen in order to assess the relative bioavailability and to demonstrate that the systemic bioavailability of ketoprofen administered topically is low enough to ensure a low incidence of gastrointestinal adverse events.
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PMID:Fast HPLC method for the determination of ketoprofen in human plasma using a monolithic column and its application to a comparative bioavailability study in man. 1940 44

A sensitive and selective liquid chromatographic-mass spectrometric (LC-MS) method for the determination of amlodipine (CAS 88150-42-9) in human plasma has been developed. Sample preparation was based on liquid-liquid extraction using NaOH and cyclohexane. Analytical determination was carried out on a C18 column interfaced with a single quadrupole mass spectrometer. Positive electrospray ionization was employed as the ionization source. The mobile phase was 10 mmol/L ammonium acetate solution-methanol (30:70, v/v) at the flow rate of 0.2 mL/min. The method was linear in the concentration range of 0.2-20 ng/mL. The lower limit of quantification was 0.2 ng/mL. Amlodipine was sensitive to UV light. The method was validated in terms of accuracy, precision, absolute recovery, and stability. The intra- and interday relative standard deviation across three validation runs over the entire concentration range was less than 8.17%. The accuracy determined at three concentrations (0.4, 2.0 and 10 ng/mL for amlodipine maleate) was within +/- 3.17% in terms of relative error. The method herein described was successfully applied for the evaluation of pharmacokinetic profiles of amlodipine maleate tablets in 20 healthy volunteers. The results showed that AUC, Tmax, Cmax and T 1/2 between the test and reference formulation have no significant difference (P > 0.05). The relative bioavailability was 103.7 +/- 12.3%.
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PMID:Liquid chromatography-mass spectrometry method for the determination of amlodipine in human plasma and its application in a bioequivalence study. 1981 60

The objective of this study was to develop a rapid and simplified, reliable high-performance liquid chromatography (HPLC) method for quantification of cefpirome (CAS 98753-19-6) in plasma. After precipitation of the plasma containing the internal standard, hydrochlorothiazide, with 5% trichloroacetic acid (TCA), the analysis of the cefpirome level in the plasma samples was carried out using a reverse-phase C18 column with the ultraviolet detector set at a wavelength of 258 nm. The chromatographic separation was accomplished with an isocratic mobile phase consisting of acetonitrile-acetate buffer pH 5. The proposed method was specific and sensitive with a lower limit of quantitation (LLOQ) of 0.5 microg/ml. This HPLC method was validated by examining the precision and accuracy for inter- and intra-day analysis in the concentration range 0.5-64.0 microg/ml. The relative standard deviation in the inter- and intra-day validation was less than 3%. Analytical recovery was more than 84%, and cefpirome was found to be stable in human plasma during both the storage and assay procedures. A satisfactory pharmacokinetic study of cefpirome was carried out in rabbits using the devised procedure.
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PMID:Development of an analytical method for cefpirome in plasma by simplified HPLC technique and its applications. 2064 24


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