Determination of moclobemide, paroxetine, and fluvoxamine in tablets by HPLC

A simple, accurate high performance liquid chromatography procedure is presented in order to determine moclobemide in Aurorix-tablets, paroxetine in Seroxat-tablets and fluvoxamine in Fevarin tablets. These drugs were chromatographed on a Nova-Pak C18, (dp = 4 microm), 150x3.9 mm i.d. column using methanol/phosphate butter adjusted to pH 2.65 with phosphoric acid (7:3, v/v) as the mobile phase to determining of the moclobemide and methanol/tetrahydrofuran/phosphate buffer at pH 2.65 (53:5:4, v/v) for determining of paroxetine and fluvoxamine. The detection was carried at 235 nm. The method was tested for linearity over the range 5-50 microg/ml. The relative standard deviation for moclobemide is 1.16, but for paroxetine and fluvoxamine is less than 1% (0.25 and 0.46 respectively).     

A high-performance liquid chromatographic method for determination of praziquantel in plasma

A simple, sensitive, selective and reproducible method based on a reversed-phase chromatography was developed for the determination of praziquantel in human plasma. Praziquantel was separated from the internal standard (diazepam) on a Luna C18 column (250 mm x 4.6mm, 5 microm particle size), with retention times of 4.8 and 6.2 min, respectively. Ultraviolet detection was set at 21 7 nm. The mobile phase consisted of acetonitrile and distilled water (70:30, v/v), running through the column at a flow rate of 1.0 ml/min. The chromatographic analysis was operated at 25 degrees C. Sample preparation (1 ml plasma) was done by a single step liquid-liquid extraction with the mixture of methyl-tert-butylether and dichloromethane at the ratio of 2:1 (v/v). Calibration curves in plasma at the concentrations 0, 50, 100, 200, 400, 800 and 1600 ng/ml were all linear with correlation coefficients better than 0.999. The precision of the method based on within-day repeatability and reproducibility (day-to-day variation) was below 15% (relative standard deviation: R.S.D.). Good accuracy was observed for both the intra-day or inter-day assays, as indicated by the minimal deviation of mean values found with measured samples from that of the theoretical values (below +/-15%). Limit of quantification (LOQ) was accepted as 5 ng using 1 ml samples. The mean recovery for praziquantel and the internal standard were greater than 90% for both praziquantel and internal standard. The method was free from interference from the commonly used antibiotic and antiparasitic drugs. The method appears to be robust and has been applied to a pharmacokinetic study of praziquantel in three healthy Thai volunteers following a single oral dose of 40 mg/kg body weight praziquantel.     

Determination of celecoxib in human plasma by high-performance liquid chromatography

A high performance liquid chromatographic method for the quantitation of celecoxib (CEL) in human plasma is presented. The method is based on liquid-liquid extraction with chloroform and reversed-phase chromatography using a Nucleosil CN column (250 mm x 4.6 mm i.d., 5 microm particle size) and UV spectrophotometer detection at 260 nm. The mobile phase consists of acetonitrile:water (60:40 (v/v)). Flutamide was used as internal standard (IS). The assay was linear in the concentration range of 10-1000 ng/ml when 0.5 ml aliquots of plasma were extracted. Within-day and between-day precision expressed by relative standard deviation is less than 4% and inaccuracy does not exceed 3%. The assay was used to analyze samples collected during human clinical studies.     

Determination of paroxetine in human saliva by reversed-phase high-performance liquid chromatography with UV detection.

A rapid and sensitive high-performance liquid chromatographic method was validated and described for determination of paroxetine in human saliva. Following liquid-liquid extraction of the drug and an internal standard (dibucaine), chromatographic separation was accomplished using a C18 analytical column with a mobile phase consisting of 0.05 mol/L sodium phosphate buffer, pH 5.0, and acetonitrile (A 30:70, v/v; B 60:40, v/v). Paroxetine and the internal standard were detected by ultraviolet absorbance at 205 nm. The average recoveries of the drug and internal standard were 92.5% and 89%, respectively. The lower limits of detection and quantification were 1 and 4 ng/ml, respectively, and the calibration curve was linear over a concentration range of 4 ng/ml. The saliva level of paroxetine in patients with depression taking 10 to 40 mg/day of the drug was significantly correlated with the plasma level of paroxetine in each patient (r = 0.617, P < 0.004, n = 19). These data indicate that the saliva level of paroxetine could be a useful marker to predict the plasma level of the drug.     

Determination of endothelin antagonist BMS182874 in plasma by high-performance liquid chromatography

A simple and rapid high performance liquid chromatography (HPLC) method was developed for the determination of BMS182874 (BMS) in mouse plasma. The drug was extracted from plasma by a liquid-liquid extraction process. The method consists of reversed-phase chromatography using a Thermo Hypersil-Keystone RP-18 5 microm, 250 x 2.1 mm column and UV spectrophotometer detection at 255 nm. The mobile phase consists of 45% (v/v) acetonitrile: 55% (v/v) trifluoroacetic acid (0.015% v/v; pH 3.0) at a flow rate of 0.6 ml/min. Validity of the method was studied and the method was precise and accurate with a linearity range from 100 ng/ml to 1000 ng/ml. The extraction efficiency was found to be 81, 84 and 87% for 100, 500 and 1000 ng/ml, respectively for spiked drug in plasma. The limit of quantification and limit of detection were found to be 50 and 10 ng/ml, respectively in plasma. Within-day and between-day precision expressed by relative standard deviation was less than 4% and inaccuracy did not exceed 4%. The assay was also used to analyze samples collected during animal studies. The suitability and robustness of the method for in vivo samples were confirmed by analysis of BMS from mouse plasma and tissues dosed with BMS.     

Sensitive determination of nefopam and its metabolite desmethyl-nefopam in human biological fluids by HPLC

Nefopam (NEF) and desmethyl-nefopam (DMN) were assayed simultaneously in plasma, globule and urine samples using imipramine as internal standard. A liquid-liquid extraction procedure was coupled with a reverse phase high-performance liquid chromatography system. This system requires a mobile phase containing buffer (15 mM KH(2)PO(4) with 5 mM octane sulfonic acid: pH 3.7) and acetonitrile (77:33, v/v) through (flow rate=1.5 ml/min) a C(18) Symmetry column (150x4.6 I.D., 5 micrometer particle size: Waters) and a UV detector set at 210 nm. Internal standard was added to 1 ml of plasma or globule sample or 0.5 ml of urine sample, prior to the extraction under alkaline ambiance with n-hexane. The limits of quantification were 1 and 2 ng/ml for both molecules in plasma and globule, respectively; 5 and 10 ng/ml for NEF and DMN in urine, respectively. The method proved to be accurate and precise: the relative error at three concentrations ranged from -13.0 to +12.3% of the nominal concentration for all molecule and biological fluid; the within-day and between-day precision (relative standard deviation %) ranged from 1.0 to 10.1% for all the molecules and biological fluids. The method was linear between 1 and 60 ng/ml for both molecules in the plasma; 2 and 25 ng/ml for both molecules in the globule; 25 and 250 ng/ml for NEF and 50 and 500 ng/ml for DMN in the urine: correlation coefficients of calibration curves (determined by least-squares regression) of each molecule were higher than 0.992 whatever the biological fluid and during the pre-study and in-study validations. This method was successfully applied to a bio-availability study of NEF in healthy subjects.     

Quantification of trimetazidine in human plasma by liquid chromatography-electrospray ionization mass spectrometry and its application to a bioequivalence study

A rapid, sensitive and specific liquid chromatography-electrospray ionization mass spectrometric (LC-ESI-MS) method has been developed for the quantification of trimetazidine in human plasma. The analyte and the internal standard (pseudoephedrine) were extracted from plasma samples with n-hexane-dichloromethane (1:1, v/v) and analyzed on a C18 column. The chromatographic separation was achieved within 3.5 min using the mobile phase consisting of methanol/0.05% formic acid (80:20, v/v) and the flow rate was 1.0 ml/min. Ion signals m/z 181.0 and 148.0 were measured in the positive mode for trimetazidine and pseudoephedrine, respectively. The calibration curves were linear within the range of 0.4 to approximately 120 ng/ml. The lower limit of quantification (LLOQ) was 0.4 ng/ml with 0.5 ml plasma sample. The intra- and inter-day precisions were lower than 12% in terms of relative standard deviation (RSD). The inter-day relative error (RE) as determined from quality control samples (QCs), ranged from -1.4% to 3.3%. This validated method was successfully applied to the bioequivalent evaluation of two brands of trimetazidine tablets in 20 healthy volunteers.     

Development and validation of an accurate HPLC method for the quantitative determination of picroside II in tablets

A simple, sensitive and accurate high performance liquid chromatographic method (HPLC) with UV detection was developed and validated to determine picroside II in a new tablet formulation with paeoniflorin as internal standard. Chromatographic separation was achieved on an Agilent XDB C18 column (250 x 4.6 mm I.D., 5 microm) using a mobile phase consisting of acetonitrile-water-acetic acid (18:82:0.4, v/v/v) at a flow rate of 1.0 ml/min. The UV detection wavelength was set at 265 nm. Linear calibration curves were obtained in the concentration range of 0.10-100 microg/ml with the limit of quantification (LOQ) of 0.10 microg/ml. The within- and between-run precisions in terms of % relative standard deviation (RSD) were lower than 5.7% and 6.3%, respectively. The accuracy in terms of % relative error (RE) ranged from -2.3% to 5.0%. This validated method was successfully applied to the determination of the content of picroside II in a new tablet formulation.     

Development and validation of a simple reversed-phase high-performance liquid chromatography method for the determination of testosterone in serum of males

An isocratic high-performance liquid chromatographic method with detection at 234 nm was developed, optimized and validated for the determination of testosterone in human serum. Propylparaben was used as internal standard. A Hypersil BDS RP-C18 column (150 mmx4.6 mm, 5 microm), was equilibrated with a mobile phase composed of acetonitrile and water (35:65, v/v) and having a flow rate of 1 ml/min. The elution time for testosterone and internal standard was approximately 11.6 and 9.9 min, respectively. Calibration curves of testosterone in serum were linear in the concentration range of 1-20 ng/ml. Limits of detection and quantification in serum were 0.4 and 1.1 ng/ml, respectively. Recovery was greater than 92%. Intra- and inter-day relative standard deviation for testosterone in serum was less than 2.1 and 3.9%, respectively. This method was applied to the determination of testosterone serum levels of 12 healthy males and data were correlated with data obtained using a radioimmunoassay method.     

High performance liquid chromatographic determination of platinum in blood and urine samples of cancer patients after administration of cisplatin drug using solvent extraction and N,N'-bis(salicylidene)-1,2-propanediamine as complexation reagent

A high performance liquid chromatographic (HPLC) procedure has been developed for the determination of cisplatin, based on the pre-column derivation of platinum(II) with reagent N,N'-bis(salicylidene)-1,2-propanediamine (H2SA2pn). The neutral platinum complex was extracted, concentrated in an organic solvent and then injected (5 microl) on a reverse phase HPLC column, Varian Micro-Pak SP C-18, 5 microm (150 mm x 4.0 mm i.d.). The complex was eluted isocratically using a ternary mixture of methanol/acetonitrile/water (40/30/30, v/v/v) at a flow rate of 1.0 ml/min and was determined by a UV detector set at 254 nm after elution. A detection limit was found to be 4.0 ng per injection. The amounts of platinum in blood serum and urine of cancer patients after administration of cisplatin were observed in a range of 221-298 ng/ml and 43-97 ng/ml with relative standard deviation (R.S.D.) of 3.6-4.6% and 3.5-4.8%, respectively. Preliminary metabolism profiles of Pt concentrations in blood and urine from the patients were established.     

Determination of paroxetine in plasma by liquid chromatography coupled to tandem mass spectrometry for pharmacokinetic and bioequivalence studies

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.     

HPTLC method to study skin permeation of acylovir

A new simple, rapid and selective high performance thin layer chromatography (HPTLC) method is developed for the quantitation of acyclovir during in vitro skin permeation studies. Separation of guinea pig skin proteins and acyclovir was achieved by employing a mobile phase consisting of chloroform–methanol–ammonia (15:9:4, v/v/v) on precoated silica gel 60F254 aluminum plates. Densitometnic analysis was carried out at 255 nm. The limit of detection and quantification were 30 and 50 ng, respectively. The calibration curve was linear in the range of 10–20 μg/ml (r=0.9965). The relative standard deviation for a sample of concentration 100 μg/ml were 1.15 and 2.85 for system and method precision, respectively. Intraday and interday variation studies gave an average 0.763 and 0.463% relative standard deviation for the three levels tested. Average recoveries of 101.8 and 100.1% were recorded for two marketed preparations studied. The method was employed to optirmize topical liposomal gel formulation of acyclovir on basis of maximum skin permeation.     

A Sensitive Method for Quantitation of Rifabutin and Its Desacetyl Metabolite in Human Biological Fluids by High-Performance Liquid Chromatography (HPLC)

Sensitive HPLC-UV methodology has been developed and validated for quantitating rifabutin, an antimycobacterial, and its 25-desacetyl metabolite, LM-565, in human plasma and urine. The HPLC separation for both plasma and urine samples was performed on an ODS, 5-µm, reverse-phase column (25 cm × 4.6-cm ID) using a mobile phase of acetonitrile/0.05 M potassium phosphate, pH 4.2, with triethylamine, (38:61.5:0.5, v/v), at a flow rate of 1.0 ml/min. The separation eluate was monitored by absorbance at 275 nm. Plasma samples (1 ml) were spiked with an internal standard (medazepam), buffered at pH 7.4 and extracted with 80:20 (v/v) hexane:ethyl acetate, and then back extracted with acidified water (0.05 M H3PO4). Linearity was established between 5.0–800 and 2.5–400 ng/ml for rifabutin and LM-565, respectively. Intraday imprecision for rifabutin and LM-565 plasma quality controls prepared at 7.3 and 3.2 ng/ml, respectively, was <15% relative standard deviation (RSD). Absolute recovery for parent drug and metabolite, from plasma, was >90% throughout the respective dynamic ranges and >70% for medazepam. Urine samples (1 ml) were acidified with 50 µl of 3.6 M H2SO4 and diluted with 0.1 M ammonium acetate. Linearity was established between 100 and 5000 ng/ml for both rifabutin and LM-565. Intraday imprecision for a urine control at 200 ng/ml was 12% RSD for either component. The method is currently being used to support Phase I kinetics program for rifabutin in prophylaxis of MAC infection of AIDS patients. Application of this method to a bioavailability assessment is presented.     

Rapid HPLC method for the simultaneous monitoring of duloxetine, venlaflaxine, fluoxetine and paroxetine in biofluids

A simple and rapid HPLC method is developed for the determination of two serotonin-norepinephrine-reuptake inhibitors (duloxetine and venlaflaxine) and two selective serotonin-reuptake inhibitors (fluoxetine and paroxetine) in human biofluids. Separation was performed on an Inertsil ODS-3 column (250 x 4.0 mm, 5 μm) with acetonitrile-ammonium acetate (0.05 M, 41:59 v/v) at 235 nm, within 7 min. SPE on Oasis(?) HLB cartridges was applied for the isolation of analytes from biofluids. The developed methodology was validated in terms of sensitivity, linearity, accuracy, precision, stability and selectivity. Relative standard deviation was less than 10.4%. Limit of detection was 0.2-0.6 ng/μl in blood plasma and 0.1-0.8 ng/μl in urine. The method was successfully applied to biofluids from a patient under duloxetine treatment.     

High-performance liquid chromatography method for determining alendronate sodium in human plasma by detecting fluorescence: application to a pharmacokinetic study in humans

A high-performance liquid chromatographic (HPLC) method was developed using diethylamine (DEA) solid-phase extraction (SPE), 9-fluorenylmethyl derivative (FMOC) and fluorescence detection for quantifying alendronate in human plasma. Sample preparation involved a manual protein precipitation with trichloroacetic acid, a manual coprecipitation of the bisphosphonate with calcium phosphate and derivatization with 9-fluorenylmethyl chloroformate in citrate buffer at pH 11.9. Liquid chromatography was performed on a Capcell Pak C(18) column (4.6 mm x 150 mm, 5 microm particles), using a gradient method starting with mobile phase acetonitrile/methanol-citrate/pyrophosphate buffer (32:68, v/v). The total run time was 25 min. The fluorometric detector was operated at 260 nm (excitation) and 310 nm (emission). Pamidronate was used as the internal standard. The limit of quantification was 1 ng/ml using 3 ml of plasma. The intra- and inter-day precision expressed as the relative standard deviation was less than 15%. The assay was applied to the analysis of samples from a pharmacokinetic study. Following the oral administration of 70 mg of alendronate sodium to volunteers, the maximum plasma concentration (C(max)) and elimination half-life were 40.94 +/- 19.60 ng/ml and 1.67 +/- 0.50 h, respectively. The method was demonstrated to be highly feasible and reproducible for pharmacokinetic studies including bioequivalence test of alendronate sodium in humans.     

Analysis of carvedilol in human plasma using hydrophilic interaction liquid chromatography with tandem mass spectrometry

A rapid, sensitive and selective method for the determination of carvedilol in human plasma was developed using hydrophilic interaction liquid chromatography with tandem mass spectrometry (HILIC-MS/MS). Carvedilol and cisapride (internal standard) were extracted from human plasma with methyl tert-butyl ether at basic pH and analyzed on an Atlantis HILIC Silica column with the mobile phase of acetonitrile-ammonium formate (50 mM, pH 4.5) (90:10, v/v). The analytes were detected using an electrospray ionization tandem mass spectrometry in the multiple-reaction-monitoring mode. The standard curve was linear (r=0.9998) over the concentration range of 0.1-200 ng/ml. The lower limit of quantification for carvedilol was 0.1 ng/ml using 50 microl plasma sample. The coefficient of variation and relative error for intra- and inter-assay at four QC levels were 1.6-4.5% and -6.4 to 4.8%, respectively. The absolute and relative matrix effect for carvedilol and cisapride were practically absent. The extraction recoveries of carvedilol and cisapride were 81.6 and 85.2%, respectively. This method was successfully applied to the bioequivalence study of carvedilol in humans.     

Determination of omeprazole in human plasma by liquid chromatography-electrospray quadrupole linear ion trap mass spectrometry

An analytical method for the determination of omeprazole in human plasma has been developed based on liquid chromatography mass spectrometry. The analyte and internal standard sildenafil are extracted from plasma by liquid-liquid extraction using diethyl ether:dichloromethane (60:40, v/v) and separated by reversed phase high-performance liquid chromatography (HPLC) using acetonitrile:methanol:10 mM ammonium acetate (37.5:37.5:25, v/v/v) as mobile phase. Detection is carried out by multiple reaction monitoring on a Q TRAP LC/MS/MS system (Q TRAP). The method has a chromatographic run time of 3.5 min and is linear within the range 0.50-800 ng/mL. Intra- and inter-day precision expressed as relative standard deviation ranged from 0.4 to 8.5% and from 1.2 to 6.8%, respectively. Assay expressed as relative error was <5.7%. The method has been applied in a bioequivalence study of two capsule formulations of omeprazole.     

Determination of saquinavir and ritonavir in human plasma by reversed-phase high-performance liquid chromatography and the analytical error function

Two simple and reproducible high-performance liquid chromatography methods with ultraviolet detection were developed and validated for the quantitation of two protease inhibitors, saquinavir and ritonavir, in human plasma. The same single liquid-liquid extraction procedure with ethyl acetate-hexane (50:50, v/v), reversed-phase column and mobile phase were used. The analyses were accomplished using a Luna C(18) column (150 mm x 4.6mm i.d.) with a C(18) guard column and, the mobile phase consisted of acetonitrile and 70 mM KH(2)PO(4) adjusted to pH 5 with 80 mM Na(2)HPO(4) (46:54, v/v). The wavelength was set at 240 nm for saquinavir and at 210 nm for ritonavir. The retention times were 6.4 min for saquinavir and 8.3 min for ritonavir. The methods were linear over the range of 100-2500 ng/ml for saquinavir and 200-2500 ng/ml for ritonavir. Intra and inter-day precision and accuracy were less than 10.2% for both drugs. Recovery were 90 and 87% for saquinavir and ritonavir, respectively. The drugs were stable at different relevant storage and working conditions. After the validation, their analytical error functions were established as standard deviation (S.D., ng/ml) = 4.84 + 7.14 x 10(-2)C (C is the theoretical concentration value) for saquinavir and S.D. (ng/ml) = 39.98 + 2.40 x 10(-5)C(2) for ritonavir.     

高效液相离子对色谱法测定糖尿病大鼠血浆中二甲双胍浓度及其药代动力学研究(英文)

本研究建立并验证了测定糖尿病大鼠血浆中二甲双胍浓度的高效液相色谱方法,以阿替洛尔为内标,加入10%高氯酸沉淀蛋白来制备血浆样品。色谱条件:AQ-C18极限色谱柱(250mm×4.6mm,5μm),流动相(pH5.05)为乙腈-水(31:69,v/v,水相中含有0.002M十二烷基磺酸钠,0.0125M磷酸二氢钾,0.015M三乙胺),流速1.0mL/min。二甲双胍在7.5-4000ng/mL范围内具有良好的线性关系(r>0.994),最低检测限(LLOQ)为7.5ng/mL,描述精密度的相对标准偏差(RSD)范围为1.87%-15.70%,准确度为93.98%-106.89%。二甲双胍和内标的回收率分别为95.40%和95.31%。不同实验条件下质控样品的稳定性相对偏差范围在±9.00%之内。该方法成功地运用到糖尿病大鼠单剂量灌胃10mg/kg二甲双胍后的药代动力学研究中,结果显示本研究采用AQ-C18极限色谱柱建立的离子对色谱法对强极性化合物如二甲双胍具有良好的分离效果。     

Sensitive LC determination of ciprofloxacin in pharmaceutical preparations and biological fluids with fluorescence detection

A simple and highly sensitive isocratic reversed-phase high-performance liquid chromatographic method (RP-HPLC) has been developed for the determination of ciprofloxacin. Separation of ciprofloxacin and anthranilic acid (internal standard) was achieved on a Kromasil 100, C(18), 5 microm (250 x 4.6 mm i.d.) reversed-phase column, using fluorescence detection with lambda(exc)=300 nm and lambda(emi)=458 nm. The mobile phase consisted of acetonitrile-methanol-acetate buffer (pH 3.60; 0.05 M) (10:30:60 v/v/v) containing 1% v/v acetic acid. The analysis was performed in less than 9 min, with a flow rate of 0.8 ml min(-1). A rectilinear relationship was observed for concentrations between 0.005 and 1.0 microg ml(-1) of ciprofloxacin in aqueous standard solutions and serum and the detection limit was 20 pg injected on-column. The intra- and inter-day relative standard deviation (n=8) ranged from 1.6 to 2.6% and from 1.9 to 4.8%, respectively, calculated at three concentration levels of standard solutions. Direct measurements of ciprofloxacin in pharmaceutical preparations and in serum, after precipitation of proteins, were performed with high precision and accuracy. The application of the method to urine samples involved a solid-phase extraction treatment of the samples using C(18) cartridges. The linear working range in urine extended from 0.05 to 2.0 microg ml(-1) and the detection limit was 0.2 ng injected on-column.