A high-performance liquid chromatography/tandem mass spectrometry method for the determination of artemisinin in rat plasma

Artemisinin is a widely used antimalarial drug. To evaluate the pharmacokinetics of artemisinin in rats, a sensitive and specific liquid chromatography/tandem mass spectrometric (LC/MS/MS) method was developed and validated for the determination of artemisinin in rat plasma. For detection, a Sciex API 4000 LC/MS/MS instrument with an electrospray ionization (ESI) TurboIonSpray inlet in the positive ion multiple reaction monitoring (MRM) mode was used to monitor precursor ([M+NH4]+) --> product ions of m/z 300.4 --> 209.4 for artemisinin and m/z 316.4 --> 163.4 for artemether, the internal standard (IS). The plasma samples were pretreated by a simple liquid-liquid extraction with ether. The standard curve was linear (r > 0.99) over the artemisinin concentration range of 1.0-200.0 ng/mL in plasma. The method had a lower limit of quantification of 1.0 ng/mL for artemisinin in 100 microL of plasma, which offered a satisfactory sensitivity for the determination of artemisinin. The intra- and inter-day precisions were measured to be within +/-5.3% and accuracy between -2.6% and 1.2% for all quality control samples, lower limit of quantification and upper limit of quantification samples. The extraction recoveries of artemisinin and the IS were 95.4 +/- 4.5% and 92.8 +/- 3.9%, respectively. This present method was successfully applied to the characterization of the pharmacokinetic profile of artemisinin in rats after oral administration.     

Sensitive HPLC-ESI-MS method for the determination of tiotropium in human plasma

A sensitive high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) assay is established for the determination of tiotropium in human plasma using benzyltriethylammonium chloride as the internal standard (IS). After being treated with C(18) cartridges, plasma samples are separated by HPLC on a reversed-phase C(18) column with a mobile phase of 40mM ammonium acetate buffer-methanol (56:44, v/v). Tiotropium is determined in a single-quadrupole MS. HPLC-ESI-MS is performed in the selected ion monitoring mode using target ions at m/z 392.0 for tiotropium and m/z 192.3 for the IS. The calibration curve is linear over the range 1.5-30 pg/mL. The intra- and inter-assay variability values are less than 10.1% and 13.6%, respectively. The mean plasma extraction recovery of tiotropium is 92.3 +/- 5.0%. The method has been successfully applied to studying the pharmacokinetics of tiotropium in healthy Chinese volunteers.     

Rapid and sensitive liquid chromatography-electrospray ionization-mass spectrometry method for the determination of eperisone in human plasma: method and clinical applications

A sensitive liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) method for determination of eperisone in human plasma using buflomedil as the internal standard (IS) is established. After being made alkaline with saturated sodium bicarbonate solution, plasma samples are extracted with a mixture of diethyl ether-cyclohexane (1:1, v/v) and separated by high-performance liquid chromatography on a reversed-phase C(18) column with a mobile phase of 10mM ammonium acetate buffer (adjusted the pH to 3.9 with acetic acid)-methanol (20:80, v/v). Eperisone is determined using ESI in a single-quadrupole MS. LC-ESI-MS is performed in the selected ion monitoring mode using target ions at m/z 260 for eperisone and m/z 308 for the IS. Calibration curves are linear over the ranges 0.02-20 ng/mL for eperisone. The intra- and interassay variability values are less than 9.0% and 11.5%, respectively. The mean plasma extraction recovery of eperisone is 91.7 +/- 6.6%. The method has been successfully applied to study the pharmacokinetics of eperisone in healthy, male, Chinese volunteers. Pharmacokinetic parameters of the reference and test tablets have been compared.     

Quantitative determination of cetirizine enantiomers in guinea pig plasma, brain tissue and microdialysis samples using liquid chromatography/tandem mass spectrometry

Sensitive enantioselective liquid chromatographic assays using tandem mass spectrometric detection were developed and validated for the determination of S-cetirizine (S-CZE) and R-cetirizine (R-CZE) in guinea pig plasma, brain tissue, and microdialysis samples. Enantioselective separation was achieved on an alpha1-acid glycoprotein column within 14 min for all methods. A cetirizine analog, ucb 20028, was used as internal standard. Cetirizine and the internal standard were detected by multiple reaction monitoring using transitions m/z 389.1 --> 200.9 and 396.1 --> 276.1, respectively. The samples were prepared using protein precipitation with acetonitrile. For guinea pig plasma, the assay was linear over the range 0.25-5000 ng/mL for both S-CZE and R-CZE, with a lower limit of quantification (LLOQ) of 0.25 ng/mL. For the brain tissue and microdialysis samples, the assays were linear over the range 2.5-250 ng/g and 0.25-50 ng/mL, respectively, and the LLOQ values were 2.5 ng/g and 0.25 ng/mL, respectively. The intra- and inter-day precision values were < or =7.1% and < or =12.6%, respectively, and the intra- and inter-day accuracy varied by less than +/-8.0% and +/-6.0% of the nominal value, respectively, for both enantiomers in all the matrices investigated.     

Simultaneous determination of docetaxel and ketoconazole in rat plasma by liquid chromatography/electrospray ionization tandem mass spectrometry

A rapid and sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) method has been developed and validated for simultaneous quantification of docetaxel and ketoconazole in rat plasma with paclitaxel as internal standard (IS). The analytes were extracted from rat plasma by using a liquid-liquid extraction technique with ethyl acetate and the LC separation was performed on a Cosmosil-C(18) analytical column (150 mm x 2.0 mm i.d., Nacalai Tesque Inc., Japan). The extracted samples were analyzed with LC/MS/MS, operating in selected reaction monitoring (SRM) mode. The SRM transitions of precursor ions to product ions were 830.3-->549.1 (m/z) for docetaxel, 531.2-->489.3 (m/z) for ketoconazole, and 876.7-->307.9 (m/z) for the IS. The calibration curves were linear over the range of 2-500 ng/mL for docetaxel and 50-20 000 ng/mL for ketoconazole, with coefficients of correlation above 0.999. The limits of quantification for docetaxel and ketoconazole were both 2 ng/mL. The limit of detection for each analyte was 1 ng/mL. The intra- and inter-day precision (CV) of analysis were within 7%, and the accuracy ranged from 95 to 110%. The overall recoveries for docetaxel and ketoconazole were about 89.0% and 91.1%, respectively. The total analysis time was only 9.0 min. This quantitation method was successfully applied to the simultaneous determination of docetaxel and ketoconazole in rat plasma and some potential interaction was found in the current coadministration pharmacokinetic study. This established method was also utilized in the in vitro and in vivo drug-drug interaction study of docetaxel and ketoconazole (to be published).     

超高效液相色谱-串联质谱法测定兔血浆中的丝裂霉素C

建立了采用超高效液相色谱-串联质谱测定兔血浆中丝裂霉素C的方法。以兔空白血浆为基质,通过添加标准溶液的方法配制含丝裂霉素C和内标物曲安奈德的样品,选用乙酸乙酯为提取溶剂,液-液萃取法处理血浆样品。采用Hypersil Gold C18分析柱(50 mm×2.1 mm, 1.9 μm),流动相为甲醇-0.1%甲酸水溶液(90:10, v/v),等度洗脱,流速0.2 mL/min,柱温35 ℃,在3 min内实现了快速分离。采用电喷雾正离子(ESI+)模式电离,选择反应监测(SRM)模式检测,以曲安奈德作为内标物进行定量。用于监测的定量离子对分别为丝裂霉素C m/z 335.2→242.2和曲安奈德m/z 435.2→397.3/415.2,用基质匹配标准溶液法进行定量。结果表明: 兔血浆中丝裂霉素C的质量浓度在1～1000 μg/L范围内线性关系良好(r=0.9978,权重系数(weighting): 1/x2);血浆中丝裂霉素C的检出限(信噪比为3)为0.2 μg/L;其平均回收率为85%～ 115%;日内及日间的相对标准偏差(RSDs)均小于15%,满足生物样品检测的要求。该方法可用于兔气管外壁给药后的血浆样品中丝裂霉素C的检测。本方法选择性强、灵敏度高、操作简便快速、重现性好,适用于丝裂霉素C药代动力学等方面的研究。     

Development of a liquid chromatography/tandem mass spectrometry assay for the quantification of PM00104, a novel antineoplastic agent, in mouse, rat, dog, and human plasma

A rapid and sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) assay was developed and validated to quantify a novel antineoplastic agent, PM00104, in mouse, rat, dog, and human plasma. The method was validated to demonstrate the specificity, limit of quantification (LOQ), accuracy, and precision of measurements. The calibration range for PM00104 was established using PM00104 standards from 0.01-5.0 ng/mL in blank plasma. The selected reaction monitoring (SRM), based on the m/z 692.2 --> 218.2 transition, was specific for PM00104, and that based on the m/z 697.2 --> 218.2 transition was specific for PM00104 ((13)C(2),(2)H(3)) (the internal standard, IS); no endogenous materials interfered with the analysis of PM00104 and IS from blank plasma. The assay was linear over the concentration range 0.01-5.0 ng/mL. The correlation coefficients for the calibration curves ranged from 0.9981-0.9999. The mean intra-day and inter-day accuracies for all calibration standards (n = 8) ranged from 97-105% (< or =5% bias) in human plasma, and the mean inter-day precision for all calibration standards was less than 8.5%. The mean intra- and inter-day assay accuracy for all quality control (QC) replicates in human plasma (n = 9), determined at each QC level throughout the validated runs, ranged from 96-112% (< or =12% bias) and from 102-105% (< or =5% bias), respectively. The mean intra- and inter-day assay precision was less than 15.0 and 11.8% for all QC levels, respectively. For the QC samples prepared in animal species plasma, the %CV values of the assays ranged from 1.8-8.8% in mouse plasma, from 3.7-13.8% in rat plasma, and from 3.0-7.2% in dog plasma. The assay accuracies ranged from 92-102% (< or =8% bias) for all QC levels prepared in mouse plasma; ranged from 93-106% (< or =7% bias) in rat plasma; and ranged from 95-114% (< or =14% bias) in dog plasma. The assay has been used to support preclinical pharmacokinetic and toxicokinetic studies and is currently used to measure PM00104 plasma concentrations to support clinical trials.     

Determination of zaltoprofen in human plasma by liquid chromatography with electrospray tandem mass spectrometry: Application to a pharmacokinetic study

In the present study, we developed a method coupling liquid-liquid extraction (LLE) to high-performance liquid chromatography (HPLC) with positive ion electrospray ionization tandem mass spectrometry (ESI-MS/MS) to determine zaltoprofen levels in human plasma, using enalapril as internal standard (IS). The high sensitivity and specificity of MS/MS detection enabled the use of small plasma volumes (250 microL) and a simple LLE procedure. Furthermore, the short run-times (2 min) involved are compatible with the requirements of large-scale clinical studies. Ion acquisition was performed in multiple reaction monitoring (MRM) mode by monitoring the transitions m/z 299.3 > 225.0 for zaltoprofen and m/z 377.4 > 234.2 for the IS enalapril. The limit of detection (LOD) was 0.01 microg/mL and the lower limit of quantitation (LLOQ) was 0.05 microg/mL. The devised method was linear over the studied range (0.05-20 microg/mL), with r2 > 0.99 and a run-time of 2 min. Intra-day precisions fell in the range 2.0-13.8%, inter-day precisions in the range 2.1-3.9%, and intra- and inter-day accuracies in the range 102.8-114.1%. The described method provides a fast and sensitive analytical tool for zaltoprofen and was successfully applied to a 24-subject pharmacokinetic study.     

Determination of roxatidine in human plasma by liquid chromatography/electrospray mass spectrometry and application to a clinical pharmacokinetic study

A rapid and sensitive liquid chromatography/mass spectrometry (LC/MS) method was developed and validated for the determination of roxatidine in human plasma. Roxatidine was extracted by single liquid-liquid extraction with tert-butyl methyl ether, and the chromatographic separation was performed on a C8 column. The total analytical run time was relatively short (5 min), and the limit of assay quantification was 2 ng/mL using 0.1 mL of human plasma. Roxatidine and the internal standard, propranolol, were monitored in selected ion monitoring (SIM) mode at m/z 307.3 and 260.3, respectively. The standard curve was linear over a concentration range from 2-500 ng/mL, and the correlation coefficients were >0.999. The mean intra- and inter-day assay accuracy ranged from 103.4-108.8% and 102.3-110.0%, respectively, and the mean intra- and inter-day precision was between 3.3-8.8% and 5.3-6.2%, respectively. The developed assay method was successfully applied to a pharmacokinetic study in human volunteers after oral administration of roxatidine acetate hydrochloride at a dose of 75 mg.     

A high-performance liquid chromatographic method for determination of the niguldipine analogue DHP-014

A simple and reliable reversed-phase high-performance liquid chromatography method was developed and validated for the determination of DHP-014, a niguldipine analogue with potent P-glycoprotein inhibitory and negligible calcium channel blocking properties, in rat plasma. DHP-014 and niguldipine hydrochloride (the internal standard) were extracted from rat plasma by liquid extraction using hexane. DHP-014 was then separated by HPLC on a C18 column and quantified by ultraviolet detection at 238 nm. The mobile phase consisted of acetonitrile-aqueous 5 mM phosphate buffer (65:35, v/v) containing 0.4% (v/v) triethylamine adjusted to pH 7.0. The mean extraction efficiency of DHP-014 was 109.0 +/- 12.9, 97.7 +/- 8.0 and 102.9 +/- 7.5% for DHP-014 concentrations of 10, 50 and 100 nM, respectively (n = 5). The method was linear over the concentration range 2.5-200 nM with a regression coefficient of 0.998. The limit of detection of DHP-014 in rat plasma was 1.0 nM. The intra- and inter-day coefficients of variation for DHP-014 in rat plasma were 4.7-7.9 and 6.9-9.9%, respectively. The intra- and inter-day accuracy was 98.2-99.5 and 97.9-103%, respectively. The bioanalytical technique was used to determine DHP-014 in plasma samples in a pharmacokinetic study of DHP-014 administered to female Sprague-Dawley rats.     

High-performance liquid chromatography analysis of curcumin in rat plasma: application to pharmacokinetics of polymeric micellar formulation of curcumin

A simple, rapid and reliable high-performance liquid chromatographic (HPLC) method was developed and validated for the determination of curcumin in rat plasma. Plasma was precipitated with acetonitrile after addition of the internal standard (IS), 4-hydroxybenzophenone. Separation was achieved on a Waters muBondapak C(18) column (3.9 x 300 mm, 5 microm) using acetonitrile (55%) and citric buffer, pH 3.0 (45%) as the mobile phase (flow rate = 1.0 mL/min). The UV detection wavelength was 300 and 428 nm for IS and curcumin, respectively. The extraction efficiencies were 97.08, 95.69 and 94.90% for 50, 200 and 1000 ng/mL of curcumin in rat plasma, respectively. The calibration curve was linear over the range 0.02-1 microg/mL with a correlation coefficient of r(2) > 0.999. The intra- and inter-day coefficients of variation were less than 13%, and mean intra- and inter-day errors were less than +/-6% at 50, 200 and 1000 ng/mL of curcumin. This assay was successfully applied to the pharmacokinetic studies of both solubilized curcumin and its polymeric micellar formulation in rats. It was found that polymeric micelles increased the half-life of curcumin 162-fold that of solubilized curcumin and increased the volume of distribution (Vd(ss)) by 70-fold.     

Determination of Paclitaxel in Human Plasma by UPLC-MS-MS

A sensitive and specific ultra-performance liquid chromatography-tandam mass spectrometry method for the quantitation of paclitaxel is established. A 200 microL human plasma sample is spiked with 13C6-labeled paclitaxel as an internal standard and extracted with 1.3 mL of tert-butyl methyl ether. The chromatographic separation is achieved within 2 min on a C18 column with methanol-0.1% aqueous formic acid (75:25, v/v) as a mobile phase at a flow rate of 0.4 mL/min. Multiple reaction monitoring mass transitions of m/z 876.2 to 307.9 and 882.2 to 313.9 are measured for paclitaxel and the internal standard, respectively. For paclitaxel at the concentrations of 1.021, 5.105, and 10.21 microg/mL in human plasma, the extraction recoveries are 105.87%, 103.91%, and 100.39%, respectively. The linear quantitation range of the method is 0.1021-20.42 microg/mL in human plasma with a correlation coefficient greater than 0.999. The intra- and inter-day accuracy for paclitaxel at 1.021, 5.105, and 10.21 microg/mL levels in human plasma fell in the ranges of 95.01-99.23% and 95.29-101.28%, and the intra- and inter-day precision were in the ranges of 6.37-10.88% and 7.21-9.05%, respectively. This method is successfully applied to the determination of the half-life of paclitaxel in human plasma.     

Determination of a novel epothilone D analog (AV-EPO-106) in human plasma using ultra-performance liquid chromatography-tandem mass spectrometry

A novel ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS-MS) method has been established for the determination of a newly synthesized epothilone D analog (AV-EPO-106) in human plasma. The plasma samples were prepared by liquid-liquid extraction with cold tert-butyl methyl ether. The chromatographic separation was achieved within 5 min on a C(18) column with water-methanol (10:90, v/v) as mobile phase at a flow-rate of 0.8 mL/min. Mass transition of m/z 568.2 to 386.1 was measured for AV-EPO-106 in positive atmospheric pressure chemical ionization mode. A detailed validation of the method was performed as per the USFDA guidelines. For AV-EPO-106 at the concentrations of 1.0, 5.0 and 10.0 microg/mL in human plasma, the absolute extraction recoveries were 86.17, 85.24 and 85.69%, respectively. The linear quantification range of the method was 0.10-20.0 microg/mL in human plasma with linear correlation coefficients greater than 0.999. The intra-day and inter-day accuracy for AV-EPO-106 at the levels of 1.0, 5.0 and 10.0 microg/mL in human plasma fell in the ranges of 98.25-100.47 and 94.19-97.25%, and the intra- and inter-day precision were in the ranges of 4.75-6.30% and 8.89-10.45%, respectively. The method was successfully applied to quantify AV-EPO-106 in human plasma to determine the half-life of this compound in human plasma.     

Simultaneous quantification of atorvastatin and active metabolites in human plasma by liquid chromatography-tandem mass spectrometry using rosuvastatin as internal standard

A simple, sensitive, selective and rapid liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantification of atorvastatin and its active metabolites ortho-hydroxyatorvastatin and para-hydroxyatorvastatin in human plasma using rosuvastatin as internal standard (IS). Following simple liquid-liquid extraction, the analytes were separated using an isocratic mobile phase on a reversed-phase C18 column and analyzed by MS in the multiple reaction monitoring mode using the respective [M+H]+ ions, m/z 559/440 for atorvastatin, m/z 575/466 for ortho-hydroxyatorvastatin, m/z 575/440 for para-hydroxyatorvastatin and m/z 482/258 for the IS. The assay exhibited a linear dynamic range of 0.1-20 ng/mL for atorvastatin and its two metabolites in human plasma. The lower limit of quantification was 100 pg/mL with a relative standard deviation of less than 8%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. The average absolute recoveries of atorvastatin, ortho-hydroxyatorvastatin, para-hydroxyatorvastatin and the IS from spiked plasma samples were 54.2 +/- 3.2, 50.1 +/- 3.8, 65.2 +/- 3.6 and 71.7 +/- 2.7%, respectively. A run time of 2.5 min for each sample made it possible to analyze more than 300 human plasma samples per day. The validated method has been successfully used to analyze human plasma samples for application in pharmacokinetic, bioavailability or bioequivalence studies.     

Rapid and sensitive determination of udenafil in plasma by LC-MS/MS for intranasal pharmacokinetic study in rats

A rapid and sensitive analytical method for udenafil in rat plasma was developed and validated using liquid chromatography-tandem mass spectrometry (LC-MS/MS). This chromatographic procedure was then applied to the in vivo pharmacokinetic studies in rats for determining the advantages of intranasal administration of the drug over oral administration. Using liquid-liquid extraction (LLE), udenafil and the internal standard (IS) sildenafil were extracted with dichloromethane from 100 μl of plasma samples. Chromatographic separation was performed using Pursuit XRS C?? column (50 mm × 2.1 mm, i.d., 3 μm, Varian Inc., CA, U.S.A.) with an isocratic mobile phase consisting of acetonitrile and 10 mM ammonium acetate (90 : 10, v/v) at a flow rate of 0.2 ml/min over a total run time of 2.5 min. Detection and quantification was performed by mass spectrometry using the multiple reaction-monitoring mode at m/z 517.4→283.1 for udenafil and m/z 475.3→100.0 for IS. Results showed that the developed method was sensitive and specific for udenafil. Linearity was obtained in the range of 0.5-1000 ng/ml. The coefficient of variation of both intra- and inter-day validation were below 11.6% and the intra- and inter-day accuracy ranged from 91.5 to 109.9%. Udenafil concentration was successfully measured from plasma after intranasal as well as after intravenous or oral administration at clinical dose (1.67 mg/kg) in rats. Moreover, the T(max) values obtained from pharmacokinetic studies suggested that administration of udenafil intranasally could be more effective than by the oral route.     

Determination of bergenin in human plasma after oral administration by HPLC-MS/MS method and its pharmacokinetic study

A highly sensitive, simple and selective high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed and applied to the determination of bergenin concentration in human plasma. Bergenin and the internal standard (IS) thiamphenicol in plasma were extracted with ethyl acetate, separated on a C(18 )reversed-phase column, eluted with mobile phase of acetonitrile-water, ionized by negative ion pneumatically assisted electrospray and detected in the multi-reaction monitoring mode using precursor --> product ions of m/z 327.1 --> 192 for bergenin and 354 --> 185.1 for the IS, respectively. The linear range of the calibration curve for bergenin was 0.25-60 ng mL(-1), with the lowest limit of quantification of 0.25 ng mL(-1), and the intra/inter-day relative standard deviation (RSD) was less than 10%. The method is suitable for the determination of low bergenin concentration in human plasma after therapeutic oral doses, and has been first and successfully used for its pharmacokinetic studies in healthy Chinese volunteers.     

Liquid chromatography/electrospray ionization mass spectrometry method for the quantification of valproic acid in human plasma

A simple, sensitive and rapid liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS) method was developed and validated for the quantification of valproic acid, an antiepileptic drug, in human plasma using benzoic acid as internal standard (IS). Following solid-phase extraction, the analytes were separated using an isocratic mobile phase on a reversed-phase C18 column and analyzed by MS in the single ion monitoring mode using the respective [M-H]- ions, m/z 143 for valproic acid and m/z 121 for the IS. The assay exhibited a linear dynamic range of 0.5-60 microg/mL for valproic acid in human plasma. The lower limit of quantification was 500 ng/mL with a relative standard deviation of less than 10%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. The average absolute recoveries of valproic acid and the IS from spiked plasma samples were 96.1+/-4.2 and 95.6+/-2.7%, respectively. A run time of 4.5 min for each sample made it possible to analyze more than 250 human plasma samples per day. The validated method has been successfully used to analyze human plasma samples for application in pharmacokinetic, bioavailability and bioequivalence studies.     

Determination of azasetron hydrochloride in rabbit plasma by liquid chromatography tandem mass spectrometry and its application

A sensitive and selective liquid chromatography tandem mass spectrometry method for determination of azasetron hydrochloride in rabbit plasma was developed. After addition of doxapram hydrochloride as internal standard (IS), protein precipitation by 10% trichloroacetic acid was used as sample preparation. Chromatographic separation was achieved on a Zorbax SB-C(18) (2.1 × 50 mm, 3.5 μm) column with acetonitrile-water as mobile phase with gradient elution. An electrospray ionization source was applied and operated in positive ion mode; multiple reaction monitoring mode was used to quantification using target fragment ions m/z 349.9 → 223.5 for azasetron hydrochloride and m/z 378.9 → 291.8 for the IS. Calibration plots were linear over the range of 6-1000 ng/mL for azasetron hydrochloride in plasma. The lower limit of quantitation for azasetron hydrochloride was 6 ng/mL. The mean recovery of azasetron hydrochloride from plasma was in the range 85.6-92.7%. The RSDs of intra-day and inter-day precision were both less than 12%. This method is simple and sensitive enough to be used in pharmacokinetic research for determination of azasetron hydrochloride in rabbit plasma.     

Development of a liquid chromatography/tandem mass spectrometry assay for the quantification of PM02734, a novel antineoplastic agent, in dog plasma

A rapid and sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) assay was developed and validated to quantify a novel antineoplastic agent, PM02734, in dog plasma. The method was validated to demonstrate the specificity, limit of quantification (LOQ), accuracy, and precision of measurements. The calibration range for PM02734 was established using PM02734 standards from 0.05 to 100 ng/mL in blank plasma. The dominating ions were doubly charged molecular ions [M+2H]2+ at m/z 740.0 instead of singly charged ones at m/z 1478.4. The selected reaction monitoring (SRM), based on the m/z 740.0 --> 212.2 transition, was specific for PM02734, and that based on the m/z 743.8 --> 212.2 transition was specific for deuterated PM02734 (the internal standard, IS); no endogenous materials interfered with the analysis of PM02734 and IS from blank plasma. The assay was linear over the concentration range 0.05-100 ng/mL. In terms of sensitivity of assay 0.05 ng/mL is a very low LLOQ, especially considering PM02734 is a peptide. The correlation coefficients for the calibration curves ranged from 0.9990 to 0.9999. The mean intraday and interday accuracies for all calibration standards (n = 9) ranged from 93 to 111% (< or =11% bias) in dog plasma, and the mean interday precision for all calibration standards was less than 6.4%. The mean intra- and interday assay accuracy for all quality control replicates in dog plasma (n = 9), determined at each QC level throughout the validated runs, ranged from 85-111% (< or =15% bias) and from 99-109% (< or =9% bias), respectively. The mean intra- and interday assay precision was less than 12.1 and 13.3% for all QC levels, respectively. The assay has been used to support preclinical pharmacokinetic (PK) and toxicokinetic studies. The results showed that preclinical samples could be monitored for PM02734 up to 168 h after dosing, which allowed us to identify multiple elimination phases and accurately estimate PK information.     

Rapid and sensitive determination of donepezil in human plasma by liquid chromatography/tandem mass spectrometry: application to a pharmacokinetic study

A liquid chromatography/tandem mass spectrometry (LC/MS/MS) method was developed and validated for the determination of donepezil in human plasma samples. Diphenhydramine was used as the internal standard. The collision-induced transition m/z 380 --> 91 was used to analyze donepezil in selected reaction monitoring mode. The signal intensity of the m/z 380 --> 91 transition was found to relate linearly with donepezil concentrations in plasma from 0.1-20.0 ng/mL. The lower limit of quantification of the LC/MS/MS method was 0.1 ng/mL. The intra- and inter-day precisions were below 10.2% and the accuracy was between -2.3% and +2.8%. The validated LC/MS/MS method was applied to a pharmacokinetic study in which healthy Chinese volunteers each received a single oral dose of 5 mg donepezil hydrochloride. The non-compartmental pharmacokinetic model was used to fit the donepezil plasma concentration-time curve. Maximum plasma concentration was 12.3 +/- 2.73 ng/mL which occurred at 3.50 +/- 1.61 h post-dosing. The apparent elimination half-life and the area under the curve were, respectively, 60.86 +/- 12.05 h and 609.3 +/- 122.2 ng . h/mL. LC/MS/MS is a rapid, sensitive and specific method for determining donepezil in human plasma samples.