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 sensitive and reproducible high performance liquid chromatographic method was developed for the determination of pipamperone (1'-[4-(4-fluorophenyl)-4-oxobutyl]-[1,4'-bipiperidine]-4'- carboxamide, Dipiperon, CAS 1893-33-0) in plasma samples. Pipamperone and its internal standard (piritramide or 1'-(3-cyano-3,3-diphenylpropyl)-[1,4'-bipiperidine]-4'-carbo xamide) were extracted from alkalinized plasma by liquid-liquid extraction and analysed on a reversed-phase (C18) column. In order to reduce analysis time, a gradient elution technique was applied. Chromatographic peaks were quantified by UV detection at two wavelengths. The method has a detection limit of 2 ng/ml, it proved to have good accuracy and precision, and was linear in the range of 2 to 400 ng/ml. The assay was extensively applied to study the pharmacokinetics in man after oral administration of the drug.
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PMID:Determination of pipamperone in human plasma by high performance liquid chromatography. 135 93

A rapid and sensitive high-performance liquid chromatographic procedure is described for the simultaneous determination of piroxicam (CAS 36322-90-4) and tenoxicam (CAS 59804-37-4) in blood, plasma and buffer solutions used in the equilibrium dialysis studies. The method can be used to measure either piroxicam and tenoxicam in these three fluids using the other as internal standard. A Nucleosil C18 and a mobile phase consisting of an acetonitrile-distilled water-acetic acid (58 : 38 : 4) mixture were used. The flow rate was 1 ml/min and the effluent was monitored at 365 nm with 0.02 AUFS (absorbance units full scale). The sensitivities of this method were 0.2 microgram/ml levels of piroxicam and tenoxicam in the plasma, blood and buffer solutions samples.
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PMID:High-performance liquid chromatographic analysis of piroxicam and tenoxicam in plasma, blood and buffer solution. Application to pharmacokinetic studies in small laboratory animals. 835 22

Latanoprost (13,14-dihydro-15(R)-17-phenyl-18,19,20-trinor-PGF2a isopropyl ester, CAS 130209-82-4 PhXA41, Xalatan) is an antiglaucoma prodrug which enhances the bioavailability of the drug into the eye compared to the corresponding acid. The pharmacokinetics and metabolism of this drug was studied in the cynomolgus monkey after daily topical administration on the eye of [13,14-(3) H] labelled latanoprost (6 micrograms per eye) during 21 days. Plasma, urine and homogenised faeces samples were purified by separation on a Sep-Pak C18 cartridge before analysis by reversed phase liquid chromatography (RP-HPLC) with one-line radioactivity detection. The maximum plasma concentration of radioactivity obtained within 10 min post dose was as a mean 7.87 +/- 3.18 ng eq./ml on day 1 and 9.31 +/- 4.21 ng eq./ml on day 21. The plasma concentration of radioactivity declined rapidly up to 3 h post-dose both on day 1 and day 21, but a small amount of tritiated water accumulated with time. The majority of the radioactivity was recovered in urine but substantial amounts were also eliminated in the faces. No latanoprost was found in plasma after repeated topical administration on the eye. The plasma profiles from HPLC separation of samples showed a rapid and complete hydrolysis of the ester. The elimination half-life of the acid of latanoprost was estimated to be 13.8 +/- 1.7 min for day 1 and 12.4 +/- 4.8 min for day 21. No induction or inhibition of the metabolism occurred after the repeated administration. By comparison with reference substances the 15-keto acid of latanoprost was found to be present in plasma and the major metabolites in urine and faeces collected during day 2 and day 20 were identified as 1,2-dinor acid of latanoprost, 1,2,3,4-tetranor acid and 1,2,3,4-tetranor lactone of latanoprost. Tritiated water was excreted in the urine and a small amount of the acid of latanoprost was excreted in the faeces. In conclusion, latanoprost was rapidly absorbed and hydrolysed to the corresponding acid after repeated topical administration to the monkey eye. The acid of latanoprost had a short half-life in plasma and it was partly converted to the 15-keto acid of latanoprost. beta-Oxidation of the acid of latanoprost was the major metabolic pathway. No induction or inhibition of the metabolism occurred upon repeated administration and no indications of accumulation of the drug or drug metabolites were observed. The pharmacokinetics of latanoprost was similar after a single and repeated topical administration.
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PMID:Pharmacokinetics of latanoprost in the cynomolgus monkey. 2nd communication: repeated topical administration on the eye. 1021 67

An improved procedure is presented for the determination of ursodeoxycholic acid (CAS 128-13-2, UDCA) in human plasma and bile after oral administration of UDCA-containing dosage forms. The plasma samples after solid-phase extraction with silica-based C18- and strong anion exchange cartridges were assayed by gas chromatography-mass spectrometry (GC-MS) using selected-ion monitoring. The hexafluoroisopropyl trifluoroacetate ester derivative of UDCA was selected for GC analysis since it is easily and rapidly prepared by a one-step reaction. Biliary UDCA levels were determined by a rapid and simple high-performance liquid chromatographic (HPLC) method with on-line sample purification. This analytical protocol was used to investigate the pharmacokinetic of a new sustained-release capsule of UDCA in comparison with a reference immediate-release preparation after single oral administration. Statistical evaluation of the area under the plasma concentration-time curves indicated that two formulations are equivalent with regard to the amount of drug absorbed. However, pharmacokinetic data showed that with the sustained-release preparation a significantly delayed mean peak plasma level was reached compared with the reference preparation. Moreover, the immediate- and extended-release capsules were found to achieve a comparable degree of biliary enrichment with UDCA.
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PMID:Evaluation of ursodeoxycholic acid bioavailability from immediate- and sustained-release preparations using gas chromatography-mass spectrometry and high-performance liquid chromatography. 1071 15

The presence of the carcinogenic N-nitrosodiethanolamine (NDELA; CAS No. 1116-54-7) in cosmetic samples was determined using an etched, C18 modified capillary in the open-tubular capillary electrochromatography technique. A very simple extraction procedure leads to a sample matrix free from interferences. The calibration curve was created using UV detection at 214 nm. The detector response was linear in the range of 5-120 ppm total amount injected. Minimum detection limits (1 ppm NDELA injected on capillary) are suitable for screening a large number of cosmetic samples. Diethanolamine and triethanolamine precursors of nitrosamines are not detected at the wavelength used. Cosmetic samples were analyzed unspiked and after addition of 60 ppm of NDELA. In spiked samples recoveries varied from 94% (hand and body lotion) to 55% (lipstick sample). NDELA was found in unspiked samples of old (5-15 years old) cosmetics at concentrations of 14.0 ppm and 35.0 ppm.
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PMID:Screening method for determining the presence of N-nitrosodiethanolamine in cosmetics by open-tubular capillary electrochromatography. 1096 37

Rosiglitazone (CAS 155141-29-0, Avandia) is a novel insulin sensitizer used in the treatment of type 2 diabetes. A sensitive high performance liquid chromatography (HPLC) method for its determination in human plasma using fluorescence detection (excitation: 247 nm, emission: 367 nm) with a suitable internal standard (I. S.) is described. Ethyl acetate was used as extraction solvent. A mobile phase consisting of phosphate buffer, acetonitrile and methanol was used at a flow rate of 1.0 ml/min on a C18 column. The absolute recovery was > 90% and the lower limit of quantitation was 5 ng/ml. The intra- and inter-day relative standard deviations ranged from 0.58-6.69% and 0.82-6.63%, respectively. The method described is simple, economical, precise and accurate and has been successfully applied in a pharmacokinetic study conducted in healthy human volunteers.
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PMID:HPLC method for the determination of rosiglitazone in human plasma and its application in a clinical pharmacokinetic study. 1218 80

The genetic control of the synthesis of stearic acid (C18:0) and oleic acid (C18:1) in the seed oil of sunflower was studied through candidate-gene and QTL analysis. Two F(2) mapping populations were developed using the high C18:0 mutant CAS-3 crossed to either HA-89 (standard, high linoleic fatty acid profile), or HAOL-9 (high C18:1 version of HA-89). A stearoyl-ACP desaturase locus (SAD17A), and an oleoyl-PC de-saturase locus (OLD7) were found to cosegregate with the previously described Es1 and Ol genes controlling the high C18:0 and the high C18:1 traits, respectively. Using linkage maps constructed from AFLP and RFLP markers, these loci mapped to LG1 (SAD17A) and to LG14 (OLD7) and were found to underlie the major QTLs affecting the concentrations of C18:0 and C18:1, explaining around 80% and 56% of the phenotypic variance of these fatty acids, respectively. These QTLs pleiotropically affected the levels of other primary fatty acids in the seed storage lipids. A minor QTL affecting both C18:0 and C18:1 levels was identified on LG8 in the HAOL-9xCAS-3 F(2). This QTL showed a significant epistatic interaction for C18:1 with the QTL at the OLD7 locus, and was hypothesized to be a modifier of Ol. Two additional minor C18:0 QTLs were also detected on LG7 and LG3 in the HA-89xCAS-3 and the HAOL-9xCAS-3 F(2) populations, respectively. No association between a mapped FatB thioesterase locus and fatty acid concentration was found. These results provide strong support about the role of fatty acid desaturase genes in determining fatty acid composition in the seed oil of sunflower.
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PMID:Stearoyl-ACP and oleoyl-PC desaturase genes cosegregate with quantitative trait loci underlying high stearic and high oleic acid mutant phenotypes in sunflower. 1258 6

A simple, sensitive and specific high-performance liquid chromatography (HPLC) method with ultraviolet detection (315 nm) was developed and validated for quantitation of faropenem (CAS 106560-14-9), the newest addition to the group of beta-lactam antimicrobials, in human plasma. Following solid-phase extraction using Waters Oasis SPE cartridges, the analyte and internal standard (hydrochlorothiazide, CAS 58-93-5) were separated using an isocratic mobile phase of 10 mmol/L acetate buffer (pH adjusted to 7.0 with dilute acetic acid) / methanol / triethyl amine (70/30/0.03, v/v/v) on reverse phase Waters symmetry C18 column. The lower limit of quantitation was 200 ng/mL, with a relative standard deviation of less than 2 %. A linear range of 200 to 25000 ng/mL was established. This HPLC method was validated with between-batch and within-batch precision of 1.6 to 2.3 % and 0.4 to 1.6 %, respectively. The between-batch and within-batch bias was -3.1 to 5.3 % and -6.0 to 1.5 %, respectively. Frequently coadministered drugs did not interfere with the described methodology. The stability of faropenem in plasma was excellent, with no evidence of degradation during sample processing (autosampler) and 30 days storage in a freezer. This validated method is sensitive, simple and repeatable enough to be used in pharmacokinetic studies.
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PMID:Quantification of faropenem in human plasma by high-performance liquid chromatography. 1643 31

A simple, sensitive and selective high-performance liquid chromatography (HPLC) method with ultraviolet detection (305 nm) was developed and validated for quantification of cefditoren (CAS 104145-95-1), a broad-spectrum orally administered cephalosporin in human plasma. Following solid-phase extraction using Waters Oasis SPE cartridges, the analyte and internal standard (hydrochlorothiazide, CAS 58-93-5) were separated using an isocratic mobile phase of 0.03 % trifluoro acetic acid buffer / acetonitrile (81/19, v/ v) on reverse phase Waters symmetry C18 column. The lower limit of quantification was 50 ng/mL, with a relative standard deviation of less than 4%. A linear range of 50 to 5000 ng/mL was established. This HPLC method was validated with between-batch and within-batch precision of 0.5 to 3.7 % and 0.5 to 2.5%, respectively. The between-batch and within-batch accuracy was 96.9 to 103.8% and 97.5 to 102.3%, respectively. Stability of cefditoren in plasma was excellent, with no evidence of degradation during sample processing (autosampler) and 30 days storage in a freezer. This validated method is sensitive, simple and repeatable enough to be used in pharmacokinetic studies.
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PMID:Quantification of the cephalosporin antibiotic cefditoren in human plasma by high-performance liquid chromatography. 1672 18

A simple, sensitive and selective high-performance liquid chromatography (HPLC) method with ultraviolet detection (230 nm) was developed and validated for the quantification of oxcarbazepine (CAS 28721-07-5), a new antiepileptic drug, and its active metabolite 10-hydroxycarbazepine (CAS 29331-92-8) in human plasma. Following solid-phase extraction, the analytes and internal standard (zaleplon, CAS 151319-34-5) were separated using an isocratic mobile phase on a reverse phase C18 column. The lower limit of quantification was 50 ng/mL for oxcarbazepine and 100 ng/mL for 10-hydroxycarbazepine with a relative standard deviation of less than 10%. A linear dynamic range of 50 to 5000 ng/mL for oxcarbazepine and of 100 to 10000 ng/mL for 10-hydroxycarbazepine was established. This HPLC method was validated with between-batch precision of 0.8 to 8.6% and 3.2 to 7.5% for oxcarbazepine and 10-hydroxycarbazepine respectively. The between-batch accuracy was 94.0 to 102.4% and 95.4 to 105.6%, respectively. Stability of oxcarbazepine and 10-hydroxycarbazepine in plasma was excellent, with no evidence of degradation during sample processing (autosampler) and 30 days storage in a freezer. This validated method is sensitive, simple and repeatable enough to be used in pharmacokinetic studies.
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PMID:Quantification of oxcarbazeipine and its active metabolite 10-hydroxycarbazepine in human plasma by high-performance liquid chromatography. 1692 33


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