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.     

Analysis and pharmacokinetics of bulaquine and its major metabolite primaquine in rabbits using an LC-UV method--a pilot study

A precise and reproducible HPLC assay has been developed and validated for simultaneous determination of bulaquine (BQ) and its metabolite primaquine (PQ) in rabbit plasma. The method, applicable to 0.5 ml plasma, involves double extraction of samples with n-hexane: isopropanol (98:2, v/v) containing dimethyl octylamine (DMOA) (0.1%, v/ v). Separations were accomplished by reversed-phase liquid chromatography using a Spheri-5 cyano column with a low pressure gradient with mobile phase consisting of ammonium acetate buffer (50 mM, pH 6.0) and acetonitrile with DMOA. The method was sensitive with a limit of quantitation of 20 ng ml(-1) in rabbit plasma for both BQ and PQ and the recoveries were > 85 and > 45%, respectively. Excellent linear relationships (r > 0.99) were obtained between the measured and added concentration ratios of the plasma concentrations over a range of 20-1000 ng ml(-1) for both the analytes. Precision and accuracy were acceptable as indicated by relative standard deviations from 1.8 to 15.1%, bias values ranging from -14.2 to 15.7%. Moreover, BQ was stable in rabbit plasma for 15 days of storage at -60 degrees C and after being subjected to three freeze-thaw cycles. The method was applied to determine the levels and pharmacokinetics of BQ in rabbits following a single 2.5 mg kg(-1) oral and intravenous dose. The BQ levels declined and the PQ levels increased with time. The PQ/BQ ratio after oral dose at 1 and 1.5 h were higher than that after intravenous dose. In the pilot preclinical pharmacokinetic study after a single 2.5 mg kg(-1) oral dose, BQ levels were determined up to 6 h (post-prandial) and 8 h (fasting). The plasma concentration versus time data were best fitted to a two-compartment open model with first-order absorption and elimination processes without lag time. The AUC(0-infinity) and the elimination t1/2 in fasted rabbit was higher than that in post-prandial rabbit indicating the effect of food on BQ pharmacokinetics.     

Determination of desoxyepothilone B in nude mice plasma by liquid-liquid extraction and reversed-phase high-performance liquid chromatography

A novel reversed-phase high-performance liquid chromatographic (HPLC) method has been established for the determination of a newly developed anti-cancer agent desoxyepothilone B (dEpo B) in nude mice plasma. The sample preparation involved deproteination of 200 microl of plasma sample first, followed by liquid-liquid extraction of the resultant supernatant with chloroform. The compound taxol was used as the internal standard. Chromatographic separations were carried out on a 250 mm x 4.6 mm Zorbax SB-phenyl column with acetonitrile-0.25% orthophosphoric acid (50/50, v/v) as mobile phase and UV detection at 250 nm. For dEpo B and taxol at the concentration level of 10 microg/ml in nude mice plasma, the absolute extraction recoveries were 85.3 and 87.2%, respectively. The linear quantification range of the method was 0.1-100 microg/ml in nude mice plasma with linear correlation coefficients greater than 0.999. The within-day and between-day relative standard deviations (R.S.D.s) for dEpo B at 0.5, 2.5 and 10 microg/ml levels in nude mice plasma fell in the range of 2.8-4.8 and 1.5-4.6%, and the within-day and between-day recoveries were in the range of 96.5-101.7 and 97.7-101.2%, respectively.     

Liquid chromatographic assay of nifedipine in human plasma and its application to pharmacokinetic studies

A highly sensitive, selective and reproducible reversed-phase high-performance liquid chromatographic method has been developed for the determination of nifedipine in human plasma with minimum sample preparation. The method is sensitive to 3 ng/ml in plasma, with acceptable within- and between-day reproducibilities and linearity (r2 > 0.99) over a concentration range from 10-200 ng/ml. Acidified plasma samples were extracted using diethyether containing diazepam as internal standard and chromatographic separation was accomplished on C18 column using a mobile phase consisting of acetonitrile, methanol and water (35:17:48, v/v). The within-day precision ranged from 2.22 to 4.64% and accuracy ranged from 102.4-106.4%. The day-to-day precision ranged from 2.34-7.07% and accuracy from 95.1-100.1%. The relative recoveries of nifedipine from plasma ranged from 91.0-107.3% whereas extraction recoveries were 88.6-93.3%. Following eight 6-week freeze-thaw cycles, nifedipine in plasma samples proved to be stable with accuracy ranging from 0.64 to 3.0% and precision ranging from 3.6 to 4.15%. Nifedipine was also found to be photostable for at least 120 min in plasma, 30 min in blood and for 60 min in aqueous solutions after exposure to light. The method is sensitive and reliable for pharmacokinetic studies and therapeutic drug monitoring of nifedipine in humans after the oral administration of immediate-release capsules and sustained-release tablets to five healthy subjects.     

Determination of nitrazepam and temazepam in plasma by high-performance liquid chromatography

A rapid and simple high-performance liquid chromatographic analysis of nitrazepam in plasma with temazepam as an internal standard is described here. Alternatively, this assay method can also be used to determine temazepam plasma concentrations with nitrazepam as the internal standard. Chloroform was used as an organic solvent for the extraction process. The percentage recoveries of nitrazepam and temazepam were 79% and 85%, respectively. The coefficient of variation of the within-day precision of the assay procedure at a concentration equal to 50 ng/ml of nitrazepam was 2.4% (n = 5), and that for day-to-day precision at the same concentration was 4.7% (n = 5). Calibration curves for nitrazepam and temazepam were linear over their therapeutic ranges. Pharmacokinetic parameters obtained with this method after a single oral dose of 5 mg of nitrazepam in five normal subjects were comparable to results obtained in previous studies.     

Pharmacokinetics and excretion of the novel anti-tuberculosis compound 1,2:5,6-di-O-isopropylidene-3-O-(phenyl cyclopropyl methanonyl)-alpha-D-glucofuranose (S-001-14) after oral doses in rats. Development of a sensitive and reproducible high performance liquid chromatography-UV method for the determination of the test compound in rat serum

A sensitive and reproducible high performance liquid chromatography (HPLC)-UV method for the determination of the novel anti-tuberculosis compound 1,2:5,6-di-O-isopropylidene-3-O-(phenyl cyclopropyl methanonyl)-alpha-D-glucofuranose (S-001-14) has been developed and validated in rat serum, urine and feces. Following extraction with hexane at alkaline pH, samples were separated on a reverse phase C18 column and quantified using UV detection at 267 nm. The mobile phase was 70% acetonitrile in ammonium acetate buffer (10 mmol/L, pH 6.0) with a flow rate of 1.0 ml/min. The method was used to determine the pharmacokinetics and excretion of S-001-14 after oral doses in rats. Linearity was satisfactory over the concentration range of 5-500 ng/ml (r2, > 0.99). Recoveries were > 90% and were consistent throughout the calibration range. The precision and accuracy were acceptable as indicated by relative standard deviation ranging from 2.72 to 9.54%, bias values ranging from 1.62 to 12.05%. Moreover, S-001-14 was stable in rat serum after being subjected to three freeze-thaw cycles and for 30 days on storage at - 60 degrees C. The method was used to determine the serum concentration-time profiles for S-001-14 after oral doses of 4, 100 and 200 mg/kg in rats. A linear pharmacokinetics was found in rats at 100 and 200 mg/kg doses with a long elimination half-life (approximately 24 h), wide distribution and bioavailability of approximately 13%. The excretion study after the 100 mg/kg oral dose revealed that S-001-14 was excreted in urine (0.002 +/- 0.001%) and feces (15.6 +/- 3.5%).     

Application of a liquid chromatographic/tandem mass spectrometric method to a kinetic study of derivative glucosamine in healthy human urine

A sensitive, selective and efficient liquid chromatographic/tandem mass spectrometric (LC/MS/MS) method was developed and validated for the determination of glucosamine in healthy human urine. Urine samples were extracted by acetonitrile and derivatized with o-phthalaldehyde/3-mercaptopropionic acid. Analysis was then carried out using ESI source and methanol/0.2% ammonium acetate-0.1% formic acid mobile phase gradient elution, with tolterodine tartrate as the internal standard. The linear calibration curve ranged from 0.41μg/ml to 82.7μg/ml. The intra-day and inter-day precisions were less than 3.93% and 10.0%, respectively. The extraction recoveries determined at three concentration levels were higher than 88.6%. The method was successfully applied for determining the urine concentration of glucosamine up to 24h after oral administration of 1g glucosamine sulfate dispersible table (containing 785.08mg glucosamine) from a clinical pharmacokinetic study in 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.     

Comparison of two extraction procedures for determination of drugs of abuse in human saliva by high-performance liquid chromatography

High performance liquid chromatography in combination with diode array detection (HPLC-DAD) was used to determine morphine, 6-acetylmorphine, cocaine, benzoylecgonine, cocaethylene, methadone and 2-ethylene-1,5-dimethyl-3,3,-diphenylpyrrolidine in human saliva. For comparison, samples were prepared by either liquid-liquid extraction in Toxitubes A or microwave-assisted extraction (MAE), by mixing 1 ml of saliva with 10 ml of chloroform and operating at 100 degrees C for 10 min. Acetonitrile and 0.02 m phosphate buffer at pH 6.5 were used as mobile phase in HPLC in gradient mode. The detector response was linear over the drug concentration range of 0.05-2.0 microg ml(-1) in human saliva. The analytical method was validated by determining its precision and accuracy (n = 5), which were lower than 5% as relative standard deviation and 6% as relative error. Limits of detection ranged from 10 to 35 ng ml(-1); mean recoveries of drugs were from 53 to 95% with Toxitubes A and from 83 to 100% with MAE at two different concentrations (0.1 and 1.0 microg ml(-1)). The proposed method was applied to 24 saliva samples from individuals poisoned with opiates and/or cocaine.     

毛细管电泳法测定泛昔洛韦的含量

目的研究毛细管电泳法测定泛昔洛韦的含量。方法用 5 0mmol/L磷酸盐缓冲液 (pH 3 .0 ) ,毛细管柱(75 μm× 5 0cm) ,以托吡卡胺为内标于 2 10nm波长处测定泛昔洛韦的含量。 结果泛昔洛韦在 0 .0 5～ 0 .5mg/ml浓度范围内与泛昔洛韦和内标峰面积之比呈良好线性关系 ,回收率为 99.5 3 % ,RSD为 0 .9% (n =10 )。结论此法结果准确 ,重现性好 ,可用于泛昔洛韦的含量测定     

UPLC-MS/MS测定beagle犬内西罗莫司血药浓度

目的建立测定beagle犬内西罗莫司（SRL）血药浓度的UPLC-MS／MS联用方法。方法色谱柱为AgilentC18柱（50mm×2．1mm,1．7μm,）;预柱为C18柱（4．0mm×3．0mm,5μm）;流动相为乙腈-水（90：10,v／v）;流速为0．30ml／min;柱温为50℃;进样室温度为4℃。离子源为ESI源;正离子方式检测;扫描方式为多反应监测（MRM）;用于定量分析的离子反应分别为m／z936．6→m／z409．7（西罗莫司）和m／z826．6→m／z415．4（内标他克莫司）。取全血样品经液-液萃取后进样20μl。结果SRL在0．50～12．00ng／ml浓度范围内呈良好的线性（r=0．9997）,定量下限0．5ng／ml,日内、日间精密度（RSD）均小于15％,方法回收率均大于90％,萃取回收率大于76％。结论本方法具有样品处理简单,方法灵敏、快速、选择性强,满足西罗莫司在beagle犬体内药物检测的要求。     

固相萃取—反相HPLC法测定血浆中二氟尼柳的浓度

采用固相萃取方法,以大孔网格树脂小柱净化样本,建立了快速、灵敏的反相HPLC法。方法在0.5～100μg·ml^-1浓度范围内线性关系良好,最低检出限0.02μg·ml^-1(S/N=2),萃取回收率和方法回收率分别为91.65%及97.25%,日内、日间精密度均小于10%。用此方法测定了人血浆中二氟尼柳的浓度,并对单剂量口服给药后的药代动力学作了初步探讨。     

High-performance liquid chromatographic analysis of norfloxacin in human tissues and plasma with fluorescence detection

A high-performance liquid chromatographic analysis with fluorimetric detection is described for the quantitative determination of norfloxacin in renal, prostatic tissues and in plasma. The analytical procedure in the tissue pretreatment, consists of purification of the obtained sample by a solid state extraction and quantitation by HPLC. The samples were chromatographed on a C(8) reversed-phase column. Analytical recoveries ranged from 95.2 to 97.6%. Within and between day precision were assessed by analysing serum containing 50 and 500 ng/ml norfloxacin. At each concentration, within day precision was 3.6% (relative standard deviation, n = 10) and day-to-day precision was 5.3% (n = 10). Limit of detection was ca 1 ng/ml.     

Determination of roxithromycin in rat lung tissue by liquid chromatography-mass spectrometry

A liquid chromatography-mass spectrometry (LC-MS) method for the determination of roxithromycin in rat lung tissue is described. Liquid-liquid extraction was adopted for sample preparation with recoveries from 72.5 to 76.9% at levels of 0.1, 5.0 and 20.0 microg/ml. Chromatographic separation was performed on a C18 column using a mixture of methanol, water and formic acid (80:20:1, v/v/v) as mobile phase delivered at a flow rate of 0.5 ml/min. Positive selected ion monitoring (SIM) mode was used for the quantification of roxithromycin at m/z 837.7 and clarithromycin (internal standard) at m/z 748.7. The linearity was obtained over the concentration range of 0.05-20.0 microg/ml and the lower limit of quantification was 0.05 microg/ml. For each QC level of roxithromycin, the intra- and inter-day precisions relative standard deviation (R.S.D.) were less than 4.1 and 7.5%, respectively, and accuracy (RE) was +/-10.0%. The proposed LC-MS method has been successfully used for the determination of roxithromycin in rat lung tissue after oral administration of roxithromycin formulations to 44 SD rats. The present study demonstrates that the concentration of roxithromycin in rat lung tissues can be significantly increased by ambroxol when they are formulated in combination.     

气相色谱双塔双柱法同时测定中药材中56种有机氯类及拟除虫菊酯类农药残留量

研究中药材中有机氯类及拟除虫菊酯类农药残留量的测定方法。样品经高速均质器均质提取, 依次经凝胶渗透色谱 (GPC) 和固相萃取柱 (SPE) 净化后, 用气相色谱双塔双柱进样, 双电子捕获检测器同时定性、定量测定。在3种中药材样品基质、3水平添加条件下, 56种农药的回收率大多在70.0%～110.0%, 相对标准偏差小于15%, 检测限大多低于0.01 mg·kg⁻¹, 符合农药多残留检测的要求。本法净化效果好、基质干扰小、灵敏度高、重现性好, 可用于中药材样品中有机氯类及拟除虫菊酯类农药残留量的检测。     

正交设计优选菟丝子中总黄酮的提取工艺

目的:确定菟丝子总黄酮的最佳回流提取工艺。方法:采取正交优化实验,以芦丁为对照品,采用紫外分光光度法对提取物中的总黄酮含量进行测定。结果:检测波长为510nm,芦丁对照品在0.095~0.475mg/mL内线性良好(r=0.9992),最佳提取工艺条件为提取时间150分钟,提取次数3次,醇浓度为50%,料液比为1:8。结论:该方法稳定,经济,工艺合理。     

Automatic determination of diltiazem and desacetyldiltiazem in human plasma using liquid-solid extraction on disposable cartridges coupled to HPLC--Part I: Optimization of the HPLC system and method validation.

A sensitive and automated method for the analysis of diltiazem and desacetyldiltiazem in plasma has been developed using liquid-solid extraction (LSE) on disposable extraction cartridges (DECs) in combination with HPLC. After isolation from plasma, the analytes are separated on a highly deactivated octyl silica column with a mobile phase of methanol-0.05 M phosphate buffer (pH 7.4) (62:38, v/v). The analytes are monitored photometrically at 238 nm. The complete preparation of the plasma sample as well as the injection of the final extract on to the analytical column are performed automatically by means of a sample processor equipped with a robotic arm to which is attached a needle dispensing the different liquids. The internal standard solution is first added to the plasma sample. The DEC is then conditioned successively with methanol and phosphate buffer (pH 7.4). A 1.0-ml volume of sample containing the internal standard solution is applied on an extraction cartridge filled with cyanopropyl silica (50 mg). After the DEC has been washed with the same buffer, the analytes are eluted with 0.16 ml of methanol. A 0.14-ml volume of buffer is then passed through the DEC and 0.25 ml of the final extract is injected onto the HPLC column. The absolute recoveries of the drugs are about 90% and the limit of detection for diltiazem is 0.8 ng ml-1. Relative standard deviations of 2.6% (within-day) and 3.7% (between-day) have been obtained for this compound at a plasma concentration of 50 ng ml-1.     

Development and optimization of a rapid HPLC method for analysis of ricobendazole and albendazole sulfone in sheep plasma

A simple, rapid and reliable high performance liquid chromatographic (HPLC) method has been developed and validated for simultaneous determination of ricobendazole (RBZ) and its main metabolite albendazole sulfone (ABZSO(2)) in sheep plasma using an isocratic system with UV detection. The method involved solid phase extraction followed by separation on a reversed phase C-18 column. Internal standard was selected by quantitative structure retention relationships (QSRRs) analysis. A method to optimize the composition of ternary components mobile phase with the assistance of multiple linear regression is described. Retention times were within 10 min. The calibration curves were linear over a concentration range of 10-1000 ng/ml for both RBZ and ABZSO(2) (r > 0.999). Intra-day relative standard deviation at low, medium and high concentration levels were <5.5% for RBZ and <4.6% for ABZSO(2); average accuracies were 98.3, 101.0 and 100.5% for RBZ and 101.0, 102.4 and 100.8% for ABZSO(2). The inter-day variations at the same concentrations were <5.9% for RBZ and <6.4% for ABZSO(2). The extraction recoveries at these concentrations for RBZ, ABZSO(2) and the internal standard were all over 96%. The limit of detection and limit of quantitation were 2.4 and 7.1 ng/ml, respectively for RBZ, and 10ng/ml for both analytes.     

固相萃取-高效液相色谱法测定血浆中尼莫地平

目的:建立一快速、灵敏的尼莫地平(NM)血药测定方法,并将其应用于NM片生物利用度的研究.方法:以尼群地平为内标,采用固相萃取的HPLC分析法.取样1.0ml.志愿者双交叉po测试品或对照品120mg.用三因素方差分析和双单侧检验其药物动力学参数.结果:NM最低检测浓度为2.00ng/ml,最低检测量为1.00ng.线性范围为5～300ng/ml.方法回收率均接近100%,RSD<5%,日内、日间重现性均<8%.结论:本分析方法快速、灵敏.重现性好.符台NM片剂生物利用度研究的要求.双单侧检验表明两种NM片剂不等效.测试品的相对生物利用度约为对照品的141.8%.     

Shelf lives of aseptically prepared medicines--stability of hydrocortisone sodium succinate in PVC and non-PVC bags and in polypropylene syringes

Parenteral aseptic preparations of hydrocortisone sodium succinate (HSS) are used frequently in hospitals, but little definitive stability information is available. The purpose of this study was to obtain ultimate shelf lives for typical formulations so that they may be prepared in bulk in appropriately licensed facilities. In the first study, the stability of HSS, 1mg/ml, was determined in polyvinyl chloride (PVC) bags and polyolefine (non-PVC) bags, in 0.9% (w/v) sodium chloride at 7 degrees C, 25 degrees C/60% relative humidity (RH) and room temperature in the light (RTL) with storage for up to 135 days. In the second study, the stability of HSS, 50 mg/ml was determined in polypropylene syringes at 5 degrees C and 25 degrees C/60%RH with storage for up to 120 days. Samples from each admixture were analysed by stability indicating high performance liquid chromatography (HPLC) and were monitored for pH, appearance of solution and container, and the rate of appearance of decomposition products. Shelf lives were calculated using the maximum rate method. HSS at a concentration of 1 mg/ml in PVC bags was stable for up to 41 days at 7 degrees C, 8 days at 25 degrees C and 7 days at RTL. It was stable in non-PVC bags for up to 48, 8 and 6 days, respectively. HSS in polypropylene syringes at a strength of 50 mg/ml was stable for up to 81 days at 5 degrees C and 6 days at 25 degrees C.