Determination of azelnidipine in human plasma by liquid chromatography-electrospray ionization-mass spectrometry

A liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) method for the determination of azelnidipine in human plasma was established. Nicardipine was used as the internal standard (IS). After adjustment to a basic pH with sodium hydroxide solution (0.1 M), plasma samples were extracted with cyclohexane-diethyl ether (1:1, v/v) and separated on a C(18) column with a mobile phase of 20 mM ammonium acetate solution-methanol-formic acid (25:75:0.5, v/v). The electrospray ionization was employed in a single quadrupole mass spectrometer for the determination. The method was linear over the concentration range of 0.05-40 ng/ml. The lower limit of quantification (LLOQ) was 0.05 ng/ml. The intra- and inter-run standard deviations were less than 9.5% and 11.0%, respectively. The method was successfully applied to study the pharmacokinetics of azelnidipine in healthy Chinese volunteers.     

HPLC法测定大鼠血浆中黄芩苷的浓度

目的建立测定大鼠血浆中黄芩苷浓度的HPLC方法。方法用甲醇-乙腈沉淀血浆蛋白,将上清液吹干后残渣再溶解后进行测定;色谱柱采用DiamonsilC18柱,以甲醇-0.2%磷酸(60:40,v/v)为流动相,流速为1.0mL/min,检测波长为280nm,选取卡马西平为内标物。结果黄芩苷在0.25～10.0μg/mL范围内呈良好线性关系(r=0.9990),日内、日间RSD均小于5%;平均相对回收率与平均提取回收率分别为98.4%和69.3%。结论该方法简单快速,适用于黄芩苷的血药浓度测定及药动学研究。     

Sensitive and rapid LC-ESI-MS method for the determination of trimetazidine in human plasma

A sensitive method, based on liquid chromatography-electrospray ionisation-mass spectrometry (LC-ESI-MS), was developed for the determination of trimetazidine in human plasma. Buflomedil was used as the internal standard (IS). Plasma samples were extracted with a mixture of cyclohexane-diethyl ether (1:1, v/v) and the analytes were chromatographically separated on a phenomenex Luna 5 mu C18 (2) 100A HPLC column with a mobile phase of 10 mM ammonium acetate buffer solution containing 0.1% acetic acid-methanol (45:55, v/v). The electrospray ionization was employed in a single quadrupole mass spectrometer for the analytical determination. The lower limit of quantification (LLOQ) was 0.5 ng/ml for trimetazidine and the measuring ranges were from 0.5 to 200 ng/ml. The intra- and inter-run standard deviation was less than 4.1% and 7.8%, respectively. The method was successfully applied to study the pharmacokinetics of trimetazidine in healthy Chinese volunteers.     

A rapid liquid chromatographic method for the determination of lamotrigine in plasma

A rapid, sensitive and simple high-performance liquid chromatographic (HPLC) method for the determination of lamotrigine in plasma is described. The drug was extracted from 100 μl of plasma with chloroform:isopropanol (95:5% v/v) in the presence of 100 μl of phosphate buffer (10 mM). The extract was evaporated and the residue was reconstituted with mobile phase and injected onto the HPLC system. The drug and the internal standard (chloramphenicol) were eluted from a Symmetry C₁₈ stainless steel column at ambient temperature with a mobile phase consisting of 0.01 M potassium phosphate–acetonitrile–methanol (70:20:10% v/v/v), adjusted to pH 6.7, at a flow rate of 1.3 ml min⁻¹ and the detector was monitored at 214 nm. Quantitation was achieved by measurement of the peak-area ratio of the drug to the internal standard and the lower limit of detection for lamotrigine in plasma was 20 ng ml⁻¹. The intraday precision ranged from 3.34 to 6.12% coefficient of variation (CV) and the interday precision ranged from 2.15 to 8.34% CV. The absolute and relative recoveries of lamotrigine ranged from 86.93 to 90.71% and from 95.18 to 107.13%, respectively. The method was applied in studying the pharmacokinetics of lamotrigine administered orally to rabbits. This reliable micro-method would have application in pharmacokinetic studies of lamotrigine where only small sample sizes are available, e.g. paediatric patients.     

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.     

Quantitative determination of amantadine in human plasma by liquid chromatography-mass spectrometry and the application in a bioequivalence study

A sensitive liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) method is developed and validated for rapid determination of amantadine in human plasma. Desloratadine was used as the internal standard (I.S.). Human plasma (0.2 mL) was first alkalified with 100 microL of sodium hydroxide (3M) and then extracted with 1 mL of n-hexane containing 1% isopropanol (v/v) and 10% dichloromethane (v/v) by vortex-mixer for 3 min. The mixture was centrifuged at 14,000 rpm for 5 min. The supernatant was evaporated to dryness and the residue was dissolved in mobile phase. Samples were separated using a Thermo Hypersil-HyPURITYC18 reversed-phase column (150 mm x 2.1 mm i.d., 5 microm). Mobile phase consisted of methanol-acetonitrile-20 mM ammonium acetate (45:10:45, v/v/v) containing 1% acetic acid with pH 4.0. Amantadine and I.S. were measured by electrospray ion source in positive selective ion monitoring mode. The good linearity ranged from 3.9 to 1000 ng/mL and the lowest limit of quantification was 3.9 ng/mL. The extraction efficiencies were approximately 70% and recoveries of method ranged from 98.53 to 103.24%. The intra-day relative standard deviations (R.S.D.) were less than 8.43% and inter-day R.S.D. below 10.59%. The quality control samples were stable when kept at room temperature for 12h, at -20 degrees C for 30 days and after four freeze/thaw cycles. The method has been successfully used to evaluation of the pharmacokinetics and bioequivalence of amantadine in 20 healthy volunteers after an oral dose of 100 mg amantadine.     

Pharmacokinetics of halofantrine and n-desbutylhalofantrine in patients with falciparum malaria following a multiple dose regimen of halofantrine

Summary Halofantrine is a new blood schizontocidal drug used for the treatment of multidrug-resistant falciparum malaria. The pharmacokinetics of halofantrine (HAL) and its principal metabolite, N-desbutylhalofantrine (BHAL), was investigated in 6 adult male patients of Melanesian origin with uncomplicated falciparum malaria. The patients received 500 mg of halofantrine hydrochloride at times 0, 6 and 12 h (total 1.5 g).All patients responded to treatment with a mean parasite clearance time of 52.7 h and a mean fever clearance time of 33.8 h. The following kinetic parameters (mean values) were determined for HAL and BHAL, respectively: maximum plasma concentration (C_max)=896 and 491 ng·ml^–1; time to reach the Cmax (t_max)=15 and 56 h; elimination half-life (t_1/2)=91 and 79 h and the mean residence time (MRT)=71 and 102 h.Based on the clinical response the plasma concentrations of HAL and BHAL were adequate for the treatment of uncomplicated falciparum malaria in the 6 patients.     

液质联用法同时测定埃罗替尼及其活性代谢产物OSI-420在BALB/c裸鼠体内的浓度及其药代动力学研究(英文)

本试验建立了一种简单快速灵敏的液质联用方法, 用以同时测定裸鼠血浆内埃罗替尼及其活性代谢物OSI-420的浓度。采用液液萃取法从血浆中提取埃罗替尼, OSI-420和内标普萘洛, 用C18反相柱进行分离, 流动相为乙腈-5 mM甲酸铵 (35:65, v/v, pH = 3.0)。所有化合物均采用电喷雾电离源, 正离子方式检测。埃罗替尼和OSI-420的最低定量下限均为0.5 ng/mL。埃罗替尼的准确度在0.07%-8.00%范围内, OSI-420准确度在-2.83%-6.67%范围内; 埃罗替尼精密度在2.28%-15.12%范围内, OSI-420精密度在1.96%-11.50%范围内。此方法应用于BALB/c裸鼠口服12.5 mg/kg埃罗替尼的药代动力学研究中, 并用二室模型拟合埃罗替尼的药代动力学, 一室模型拟合OSI-420的药代动力学。代谢为OSI-420的埃罗替尼占埃罗替尼总量的10%, 比文献中的这一比值大一倍, 表明种属间埃罗替尼的代谢存在差异。     

Determination of droperidol in plasma by liquid chromatography

A reversed-phase high performance liquid chromatographic method is described for the determination of droperidol concentrations in plasma. Following extraction, separation of droperidol and the internal standard flurazepam was achieved with a Spherisorb Nitrile, 5 μm, S5CN {ce:inline-formula}250 mm × 4.6 mm{/ce:inline-formula} column at 200 nm. The mobile phase was phosphate buffer (0.05 M, pH 2.4), acetonitrile and ethanol (65:20:15, v/v/v). The assay was rapid, sensitive and linear over the range 2–4000 ng ml ⁻¹. Precision of the assay expressed as the intra- and inter-day relative standard deviations (%RSD) did not exceed 10%. Flunitrazepam, midazolam and nitrazepam were also resolved with this technique and did not interfere with droperidol or flurazepam. Resolution of all five compounds was complete in less than 6 min. The assay was used to study the pharmacokinetics of high dose droperidol infusions during and after cardiac surgery.     

Rapid and simple method for detection of fenofibric acid in human serum by high-performance liquid chromatography

A sensitive HPLC method for the determination of fenofibric acid (FA), the active form of fenofibrate in serum is described. FA from human serum samples was isolated by an easy one-step extraction procedure with a mixture of n-hexane and ethylacetate (90:10, v/v). The recovery was 84.8% of the total Fa in serum. The compound was separated isocratically on a reversed phase with acetonitrile and 0.02 M phosphoric acid (55:45, v/v) at a flow-rate of 1.0 ml/min. Absorbance at 287 nm was recorded for quantification. Validation presents a detection limit of 0.03 microgram/ml and a quantification limit of 0.1 microgram/ml (relative standard deviation at 0.1 microgram/ml = 7.1%). For an extensive validation of this method we determined the serum levels of FA in one young male volunteer and examined the pharmacokinetics of standard, mikronized and slow release formulation of fenofibrate after oral intake. This method is a rapid and reliable tool for quantitative determination of fenofibric acid in pharmacokinetic investigations.     

Determination of clofazimine in leprosy patients by high-performance liquid chromatography

An original, simple, specific, and rapid high-performance liquid chromatography assay for the determination of clofazimine in human plasma is presented. The procedure consists of extracting the drug and the internal standard (medazepam) from 0.5 mL plasma with dichloromethane/diisopropyl ether (1:1, v/v) at pH 3.0, after precipitating the proteins with methanol. The drugs were then quantitated on a reversed-phase C8 using a mobile phase consisting of a mixture of methanol/0.25 N sodium acetate buffer at pH 3.0 (74:26, v/v). The flow-rate and wavelength were set at 1 mL/min and 286 nm, respectively. The precision, linearity, and limit of quantitation of the method were within acceptable limits. The method was considered adequate and could be applied in studies involving blood level monitoring and pharmacokinetics in leprosy patients.     

Micro-method for the determination of piperacillin in plasma by high-performance liquid chromatography

A simple and sensitive high-performance liquid chromatographic method for the determination of piperacillin in plasma is described. A C8 reversed-phase column was used with a mobile phase consisting of methanol-water-triethylamine (550:450:4, v/v/v) adjusted to pH = 3 with orthophosphoric acid and UV detection at 270 nm. Cephalothin was used as internal standard. The method involves a plasma protein precipitation with acetonitrile followed by extraction of endogenous compound with chloroform and injection of the upper aqueous phase into the chromatograph. Within-day and between-day assays give relative standard deviations less than or equal to 5.7%. The detection limit is 0.2 microgram ml-1. Stability studies show that piperacillin degradation starts at -4 degrees C. Therefore, samples have to be processed promptly and stored at -20 degrees C. The method described is convenient for clinical monitoring and for pharmacokinetic studies.     

气质联用（GC／MS）研究吗啡控释片的药代动力学

本实验采用磷酸可待因做内标，经液相萃取、乙酸酐衍生化处理后，用ＧＣ／ＭＳ的ＳＩＭ（选择性离子监测）定量方法测定血中吗啡的浓度。标准曲线在１．０￣６０ｎｇ／ｍｌ之间呈良好的线性关系，日间日内ＲＳＤ小于９．０％，回收率可达９６％。并进行了８例肿瘤病人口服３０ｍｇ吗啡控释片、普通片的药代动力学的研究。主要的药代动力学参数：控释片和普通片的Ｃｍａｘ分别为：１７．５、２０．８ｎｇ／ｍｌ。ｔ１／２分别为５．０     

决明子中蒽醌类成分在大鼠体内的药动学

目的:建立大鼠血浆中决明子蒽醌类成分的RP-HPLC定量分析方法,并用于大鼠体内蒽醌类药动学研究。方法:采用Zorbax Extend-C18(250 mm×4.6 mm,5μm)(Palo Alto,CA,USA)色谱柱,以乙腈-0.3%醋酸水为流动相进行梯度,流速1.0mL.min-1,检测波长258 nm,柱温28℃。采用RP-HPLC测定决明子中芦荟大黄素(aloe-emodin)、美决明子素(obtusifo-line)和大黄酚(chrysophanol)3个蒽醌类指标成分在大鼠血浆的浓度,并根据测定结果求算药动学参数。结果:建立了决明子中芦荟大黄素、美决明子素和大黄酚在大鼠血浆中的含量测定方法。实验结果表明蒽醌类成分在大鼠体内吸收迅速,消除也较快。结论:本方法简便、准确、专属性强,可以应用于大鼠灌胃给药决明子蒽醌类提取物后的药动学研究     

High-performance liquid chromatography-electrospray ionization mass spectrometry determination of sodium ferulate in human plasma

A selective and sensitive high-performance liquid chromatography-electrospray ionization mass spectrometry method has been developed for the determination of sodium ferulate in human plasma. The sample preparation was a liquid-liquid extraction and chromatographic separation was achieved with an Agilent ZORBAX SB-C(18) (3.5 microm, 100 mm x 3.0 mm) column, using a mobile phase of methanol-0.05% acetic acid 40:60 (v/v). Standard curves were linear (r(2)=0.9982) over the concentration range of 0.007-4.63 nM/ml and had acceptable accuracy and precision. The within- and between-batch precisions were within 12% relative standard deviation. The lower limit of quantification (LLOQ) was 0.007 nM/ml. The validated HPLC-ESI-MS method has been used successfully to study sodium ferulate pharmacokinetics, bioavailability and bioequivalence in 20 healthy volunteers.     

HPLC-UV method development and validation for 16-dehydropregnenolone, a novel oral hypolipidaemic agent, in rat biological matrices for application to pharmacokinetic studies

An accurate and precise HPLC assay has been developed and validated for determination of dehydropregnenolone (DHP) in rat plasma, bile, urine and feces. Separation was achieved using a C-18 reversed phase column with a mobile phase comprising of acetonitrile and deionized water (55:45% v/v) using a UV detector, set at a wavelength of 248 nm. The method, applicable to 200-microl plasma, bile and urine, involved double extraction of the samples with n-hexane. The sample clean up for feces involved single extraction of 50 mg of sample with 3 ml of acetonitrile. The method was sensitive with a limit of quantitation of 20 ng/ml in all the matrices and absolute recovery >92%. Precision and accuracy were within the acceptable limits, as indicated by relative standard deviation varying from 4.7 to 11.2% and bias values ranging from 1.8 to 8.8%. Moreover, DHP was stable in plasma, bile and urine up to 90 days of storage at -60 degrees C and after being subjected to three freeze-thaw cycles. The method was applied to generate the pharmacokinetics of DHP in rats after oral and intravenous administration.     

高效液相色谱法测定人体血浆中吡喹酮及相对生物利用度

目的建立高效液相色谱法测定血浆中吡喹酮浓度。方法血浆样品沉淀后经NUCLEODUR100-5C18柱分离,流动相为乙腈-水-四氢呋喃=51：47：2（v/v/v）。24名健康志愿者采用自身对照随机交叉试验设计,分别单剂量口服吡喹酮片参比制剂（R）或受试制剂（T）1．2g后测定两者相对生物利用度。结果血浆中吡喹酮在25～3200μg·L^-1线性良好,最低定量浓度为25μg·L^-1;方法学回收率为104．3％～119．9％（n=15）;精密度（RSD）实验结果表明日内、日间变异均〈6．9％（n=15）。与R相比,T的相对生物利用度为104．0％±24．8％。结论该法简单,准确度高,灵敏度好;方差分析结果表明T与R的主要药动学参数之间无显著差异,2制剂生物等效。     

Determination of clarithromycin in human plasma by liquid chromatography-electrospray ionization tandem mass spectrometry

A rapid and sensitive method has been developed for the determination of clarithromycin in human plasma with liquid chromatography-tandem mass spectrometry. Clarithromycin and the internal standard, telmisartan were precipitated from the matrix (50 microl) with 200 microl acetonitrile and separated by HPLC using formic acid:10 mM ammonium acetate:methanol (1:99:400, v/v/v) as the mobile phase. The assay based on detection by electrospray positive ionization mass spectrometry in the multiple-reaction monitoring mode was finished within 2.4 min. Linearity was over the concentration range 10-5000 ng/ml with a limit of detection of 0.50 ng/ml. Intra- and inter-day precision measured as relative standard deviation were <3.73% and <9.93%, respectively. The method was applied in a bioequivalence study of two tablet formulations of clarithromycin.     

Validated liquid chromatography-tandem mass spectrometric method for the quantitative determination of daidzein and its main metabolite daidzein glucuronide in rat plasma

A highly selective and sensitive liquid chromatographic-tandem mass spectrometric (LC-MS-MS) method was developed and validated to determine daidzein and its main metabolite daidzein glucuronide in rat plasma. The analytes and internal standard genistein were extracted from plasma samples by n-hexane-diethyl ether (1:4, v/v), and separated on a C18 column. The mobile phase consisted of acetonitrile-water-formic acid (80 : 20: 1, v/v/v). Detection was performed on a triple quadrupole tandem mass spectrometer by selected reaction monitoring (SRM) mode via atmospheric pressure chemical ionization (APCI) source. The method has a limit of quantification of 0.24 ng/ml. The linear calibration curves were obtained in the concentration range of 0.24-1000 ng/ml. The intra- and inter-day precisions were lower than 13.2% in terms of % RSD. The accuracy ranged from -0.5% to 2.4% in terms of % RE (relative error). This method was successfully applied to the determination of plasma concentration of daidzein and its main metabolite daidzein glucuronide in rats after an oral administration of 20 mg/kg daidzein.     

健康人血浆中伪麻黄碱浓度的LC-MS法测定

目的建立人血浆中伪麻黄碱的LC—MS测定法。方法血浆中加入内标格列吡嗪，用甲醇提取后，采用选择性离子检测（SIM）方法测定其血药浓度。10名健康受试者口服受试制剂后，用LC—MS测定血浆中伪麻黄碱浓度。色谱柱：XTerra MS C18（3．5μm×100mm×2．1mm）；流动相：甲醇-5mmol·L^-1的醋酸铵水溶液（90：10，v／v）；流速：0．2ml·min^-1；柱温：25℃。结果标准曲线线性范围为5．01～1002．00μg·L^-1，标准曲线线性关系良好，回归方程为：f=0．00332×C＋0．00088（r=0．9997，n=5），定量下限为（LLOQ）为5．01μg·L^-1。高、中、低三种浓度的日内和日间变异均小于10．0％，回收率在89．6％～95．1％。结论本方法操作简便，灵敏度高，样品稳定性良好，适用于伪麻黄碱的临床血药浓度检测、生物利用度和药代动力学研究。