Metabolic and pharmacokinetic studies of curcumin, demethoxycurcumin and bisdemethoxycurcumin in mice tumor after intragastric administration of nanoparticle formulations by liquid chromatography coupled with tandem mass spectrometry

This paper aims to investigate the metabolism and pharmacokinetics of curcumin, demethoxycurcumin and bisdemethoxycurcumin in mice tumor. To improve water solubility, nanoparticle formulations were prepared as curcuminoids-loaded solid lipid nanoparticles (curcuminoids-SLNs) and curcumin-loaded solid lipid nanoparticles (curcumin-SLNs). After intragastric administration to tumor-bearing ICR mice, the plasma and tumor samples were analyzed by liquid chromatography with ion trap mass spectrometry. We discovered that curcuminoids were mainly present as glucuronides in plasma, whereas in free form in tumor tissue. A validated LC/MS/MS method was established to determine the three free curcuminoids in tumor homogenate. Samples were separated on a Zorbax SB-C(18) column, eluted with acetonitrile-water (containing 0.1% formic acid), and detected by TSQ Quantum triple quadrupole mass spectrometer in selected reaction monitoring mode. The method showed good linearity (r(2)=0.997-0.999) over wide dynamic ranges (2-6000 ng/mL). Variations within- and between-batch never exceeded 11.2% and 13.4%, respectively. The extraction recovery rates ranged from 78.3% to 87.7%. The pharmacokinetics of curcuminoids in mice tumor fit two-compartment model and first order elimination. For curcumin-SLNs group, the dosing of 250 mg/kg of curcumin resulted in AUC((0-48 h)) of 2285 ngh/mL and C(max) of 209 ng/mL. For curcuminoids-SLNs group, the dosing equivalent to 138 mg/kg of curcumin resulted in higher tumor concentrations (AUC=2811 ngh/mL, C(max)=285 ng/mL). It appeared that co-existing curcuminoids improved the bioavailability of curcumin.     

Determination of vandetanib in human plasma and cerebrospinal fluid by liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS)

A sensitive and precise LC-ESI-MS/MS method for the determination of vandetanib (ZD6474) in human plasma and cerebrospinal fluid (CSF) using [(13)C,d(3)]-ZD6474 as an internal standard (ISTD) was developed and validated. Sample preparation consisted of a simple liquid-liquid extraction with tert-butyl methyl ether containing 0.1% or 0.5% ammonium hydroxide. ZD6474 and ISTD were separated on a Kinetex C18 column (2.6 μm, 50 mm × 2.1 mm) at ambient temperature with an isocratic mobile phase (acetonitrile/10mM ammonium formate=50/50, v/v, at pH 5.0) delivered at 0.11 mL/min. The retention time of both compounds was at 1.60 min in a runtime of three min. Detection was achieved by an API-3200 LC-MS/MS system, monitoring m/z 475.1/112.1 and m/z 479.1/116.2 for vandetanib and ISTD, respectively. The method was linear in the range of 0.25-50 ng/mL (R(2) ≥ 0.990) for the CSF curve and from 1.0 to 3000 ng/mL (R(2) ≥ 0.992) for the plasma curve. The mean recovery for vandetanib was 80%. Within-day and between-day precisions were ≤ 8.8% and ≤ 5.9% for CSF and plasma, respectively. Within-day and between-day accuracies ranged from 95.0 to 98.5% for CSF, and from 104.0 to 108.5% for plasma. Analysis of plasma from six different sources showed no matrix effect for vandetanib (MF=0.98, %CV ≤ 4.97, n=6). This method was successfully applied to the analysis of pharmacokinetic samples from children with brain tumors treated with oral vandetanib.     

Determination of tegaserod by LC-ESI-MS/MS and its application to a pharmacokinetic study in healthy Chinese volunteers

A simple, rapid and sensitive high performance liquid chromatography-electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS) assay for determination of tegaserod in human plasma using diazepam as internal standard (IS) was established. After adjustment to a basic pH with sodium hydroxide, plasma was extracted by ethyl acetate and separated by high performance liquid chromatography (HPLC) on a reversed-phase C18 column with a mobile phase of methanol: 5 mM ammonium acetate (75:25, v/v, adjusting the pH to 3.5 with glacial acetic acid). The quantification of target compounds was obtained by using multiple reaction monitoring (MRM) transitions; m/z 302.5, 173.2 and 285.4, 193.2 were measured in positive mode for tegaserod and internal standard (diazepam), respectively. The lower limit of quantification (LLOQ) was 0.05 ng/ml. The calibration curves were linear over the range 0.05-8.0 ng/ml (r=0.9996) for tegaserod. The mean absolute recovery of tegaserod was more than 85.56%. Intra- and inter-day variability values were less than 9.21% and 10.02%, respectively. The samples were stable for 8h under room temperature (25 degrees C, three freeze-thaw cycles in 30 days and for 30 days under -70 degrees C). After administration of a single dose of tegaserod maleate 4 mg, 6 mg and 12 mg, respectively, the area under the plasma concentration versus time curve from time 0 h to 12 h (AUC0-12) were (2.89+/-0.88), (5.32+/-1.21) and (9.38+/-3.42) ng h/ml, respectively; peak plasma concentration (Cmax) were (1.25+/-0.53), (2.21+/-0.52) and (4.34+/-1.66) ng/ml, respectively; apparent volume of distribution (Vd/F) were (6630.5+/-2057.8), (7615.2+/-2242.8) and (7163.7+/-2057.2) l, respectively; clearance rate (CL/F) were (1851.4+/-496.9), (1596.2+/-378.5) and (1894.2+/-459.3) l/h, respectively; time to Cmax (Tmax) were (1.00+/-0.21), (1.05+/-0.28) and (1.04+/-0.16) h, respectively; and elimination half-life (t1/2) were (3.11+/-0.78), (3.93+/-0.92) and (3.47+/-0.53) h, respectively; MRT were (3.74+/-0.85), (4.04+/-0.56) and (3.28+/-0.66) h, respectively. The essential pharmacokinetic parameters after oral multiple doses (6mg, b.i.d) were as follows: Cssmax, (2.72+/-0.61) ng/ml; Tmax, (1.10+/-0.25) h; Cssmin, (0.085+/-0.01) ng/ml; Cav, (0.54+/-0.12) ng/ml; DF, (4.84+/-0.86); AUCss, (6.53+/-1.5) ngh/ml. This developed and validated assay method had been successfully applied to a pharmacokinetic study after oral administration of tegaserod maleate in healthy Chinese volunteers at a single dose of 4 mg, 6 mg and 12 mg, respectively. The pharmacokinetic parameters can provide some information for clinical medication.     

Determination of Cloretazine (VNP40101M) and its active metabolite (VNP4090CE) in human plasma by liquid chromatography electrospray tandem mass spectrometry (LC-ESI-MS/MS)

A sensitive method for the determination of Cloretazine (VNP40101M) and its metabolite (VNP4090CE) with an internal standard (ISTD) in human plasma was developed using high-performance liquid chromatographic separation with tandem mass spectrometric detection. Acidified plasma samples (500 microL) were prepared using solid phase extraction (SPE) columns, and 25 microL of the reconstituted sample was injected onto an Ascentis C18 HPLC column (3 microm, 5 cmx2.1 mm) with an isocratic mobile phase. Analytes were detected with an API-3000 LC-MS/MS System at unit (Q1) and low (Q3) resolution in negative multiple reaction monitoring mode: m/z 249.0 (precursor ion) to m/z 114.9 (product ion) for both Cloretazine (at 3.64 min) and VNP4090CE (at 2.91 min), and m/z 253.0 (precursor ion) to m/z 116.9 (product ion) for the ISTD. The mean recovery for Cloretazine (VNP40101M) and its metabolite (VNP4090CE) was greater than 87% with a lower limit of quantification of 1.0 ng/mL for Cloretazine (S/N=9.7, CV相似文献   

Stereoselective metabolism of metoprolol: enantioselectivity of alpha-hydroxymetoprolol in plasma and urine

Direct stereoselective separation on chiral stationary phase was developed for HPLC analysis of the four stereoisomers of alpha-hydroxymetoprolol in human plasma and urine. Plasma samples were prepared using solid-phase extraction columns and urine samples were prepared by liquid-liquid extraction. The stereoisomers were separated on a Chiralpak AD column at 24 degrees C with fluorescence detection and a mobile phase consisting of a mixture of hexane:ethanol:isopropanol:diethylamine (88:10.2:1.8:0.2) for plasma samples and hexane:ethanol:diethylamine (88:12:0.2) for urine samples. Calibration curves for the individual stereoisomers were linear within the concentration range of 2.0-200 ng/ml plasma or 0.125-25 microg/ml urine. The methods were validated with intra- and interday variations less than 15%. The absolute configuration of the pure stereoisomers were assigned by circular dichroism spectra. The methods were employed to determine the concentrations of alpha-hydroxymetoprolol stereoisomers in a metabolism study of multiple-dose administration of racemic metoprolol to hypertensive patients phenotyped as extensive metabolizers of debrisoquine. We observed stereo-selectivity in the alpha-hydroxymetoprolol formation favoring the new 1'R chiral center from both metoprolol enantiomers (AUC(0-24) (1'R1'S) = 3.02). The similar renal clearances (Cl(R)) of the four stereoisomers demonstrated absence of stereoselectivity in their renal excretion. (-)-(S)-metoprolol was slightly more alpha-hydroxylated than its antipode (AUC(0-24) (2S/2R) = 1.19), suggesting that this pathway is not responsible for plasma accumulation of this enantiomer in humans.     

First LC-MS/MS electrospray ionization validated method for the quantification of perindopril and its metabolite perindoprilat in human plasma and its application to bioequivalence study

A high throughput bioanalytical method based on solid phase extraction and liquid chromatography-tandem mass spectrometry (LC-MS/MS), has been developed for the estimation of perindopril and its metabolite perindoprilat, an angiotensin-converting enzyme inhibitor in human plasma. Ramipril was used as internal standard (IS). The extraction of perindopril, perindoprilat and ramipril from the plasma involved treatment with phosphoric acid followed by solid phase extraction (SPE) using hydrophilic lipophilic balance HLB cartridge. The SPE eluate without drying were analyzed by LC-MS/MS, equipped with turbo ion spray (TIS) source, operating in the negative ion and selective reaction monitoring (SRM) acquisition mode to quantify perindopril and perindoprilat in human plasma. The total chromatographic run time was 1.5 min with retention time for perindopril, perindoprilat and ramipril at 0.33, 0.35 and 0.30 min. The developed method was validated in human plasma matrix, with a sensitivity of 0.5 ng/ml (CV, 7.67%) for perindopril and 0.3 ng/ml (CV, 4.94%) for perindoprilat. This method was extensively validated for its accuracy, precision, recovery, stability studies and matrix effect especially because the pattern of elution of all the analytes appears as flow injection elution. Sample preparation by this method yielded extremely clean extracts with very good and consistent mean recoveries; 78.29% for perindopril, 76.32% for perindoprilat and 77.72% for IS. The response of the LC-MS/MS method for perindopril and perindoprilat was linear over the range 0.5-350.0 ng/ml for perindopril and 0.3-40 ng/ml for perindoprilat with correlation coefficient, r>/=0.9998 and 0.9996, respectively. The method was successfully applied for bioequivalence studies in human subjects samples with 4 mg immediate release (IR) formulations.     

Enantioselective analysis of citalopram and demethylcitalopram in human and rat plasma by chiral LC-MS/MS: application to pharmacokinetics

Citalopram (CITA) is available as a racemic mixture and as a pure enantiomer. Its antidepressive action is related to the (+)-(S)-CITA and to the metabolite (+)-(S)-demethylcitalopram (DCITA). In the present investigation, a method for the analysis of CITA and DCITA enantiomers in human and rat plasma was developed and applied to the study of pharmacokinetics. Plasma samples (1 ml) were extracted at pH 9.0 with toluene:isoamyl alcohol (9:1, v/v). The CITA and DCITA enantiomers were analyzed by LC-MS/MS on a Chiralcel OD-R column. Recovery was higher than 70% for both enantiomers. The quantification limit was 0.1 ng/ml, and linearity was observed up to 500 ng/ml plasma for each CITA and DCITA enantiomer. The method was applied to the study of the kinetic disposition of CITA administered in a single oral dose of 20 mg to a healthy volunteer and in a single dose of 20 mg/kg (by gavage) to Wistar rats (n = 6 for each time). The results showed a higher proportion of the (-)-(R)-CITA in human and rat plasma, with S/R AUC ratios for CITA of 0.28 and 0.44, respectively. S/R AUC ratios of DCITA were 0.48 for rats and 1.04 for the healthy volunteer.     

Determination of testosterone in saliva and blow of bottlenose dolphins (Tursiops truncatus) using liquid chromatography-mass spectrometry

A rapid, accurate and reproducible assay utilising high performance liquid chromatography-mass spectrometry (LC-MS) has been developed and validated for determining testosterone concentrations in saliva and blow of bottlenose dolphins. Sample preparation used solid phase extraction with specific preconditioning of cartridges. Analytes were eluted with 100% acetonitrile, dried under nitrogen and stored at -80 degrees C. Samples were reconstituted in 60% acetonitrile for LC-MS analysis. Chromatographic separation was achieved with an Alltech Macrosphere C8 stainless steel analytical column (2.1 mm x 150 mm i.d., 5 microm particle size, 300 angstroms pore size) using a 55% mobile phase B isocratic method (mobile phase A = 0.5% acetic acid; mobile phase B = 0.5% acetic acid, 90% acetonitrile). Samples were analysed in SIM at m/z 289.20 (testosterone mw 288.40) and a positive ion ESI. The limit of quantification was 0.5 ng/ml with a limit of detection of 0.2 ng/ml. The concentration curve was linear from 0.5 to 50 ng/ml (y = 0.01x + 0.0045, r(2) = 0.959, r = 0.979, p < 0.001). The R.S.D.s of intra- and inter-batch precision were less than 15% for saliva and 11% blow. Recovery of the assay for saliva was 93.0 +/- 7.9% (50 ng/ml) and 91.5 +/- 3.72% (1 ng/ml), and for blow was 83.3 +/- 6.8% (50 ng/ml) and 85.8 +/- 4.6% (1 ng/ml). Recovery of the internal standard in saliva was 73.0 +/- 14.2% and in blow was 78.63 +/- 4.29. The described assay was used to determine the presence of endogenous testosterone in saliva (9.73-23 ng/ml, n = 10) and blow (14.71-86.20 ng/ml, n = 11) samples of captive bottlenose dolphins.     

Determination of physostigmine in plasma by high-performance liquid chromatography and fluorescence detection

Physostigmine (PHY) is an anticholinergic drug used in the treatment of neuromuscular disorders and organophosphate poisoning. We described a sensitive, accurate, and reproducible method for PHY determination in biological materials. The method utilized a liquid/liquid, ion pair extraction, normal phase HPLC separation, and fluorometric quantitation at 240 nm excitation and 360 nm emission wavelength. We used neostigmine as a stabilizing agent to protect PHY from degradation and dimethylphysostigmine as an internal standard. The peak-height ratio vs concentration was linear over a working range from 0.50 to 25.0 ng/ml of PHY in plasma. Sensitivity of the method was 100 pg/ml of plasma which was the limit of quantitative detection under the experimental conditions used. Precision of the method was evaluated using plasma spiked with two concentrations of PHY: 1.0 and 10.0 ng/ml. Intra-day coefficient of variation (CV) ranged from 3.8 to 5.3%, and inter-day CV ranged from 1.8 to 3.6% for the two levels. The average recovery was 92%. We applied the method to examine the stability of PHY in plasma stored at -15 and -80 degrees C. The data indicated that PHY can be stored at either temperature for 9 weeks without undergoing significant alterations.     

Liquid chromatography-tandem mass spectrometric determination of a new antibacterial agent (AVE6971) in human white blood cells

An LC-MS/MS assay for the quantitative determination of a new antibacterial agent (AVE6971) has been developed and validated in human white blood cells (WBC). The assay involved a lysing procedure of white blood cells and ultra centrifugation of the extracts. Chromatography was performed on a Supelcosil ABZ+ C(18) (2.1 mm x 50 mm, 5 microm) column using a mobile phase consisting of methanol/acetonitrile/10mM ammonium formate mixture (10:30:60, v/v/v) at a flow rate of 0.2 ml/min. The linearity was within the range of 10-10000 ng/ml of extracts, corresponding to 0.5-500 ng of AVE6971 in WBC pellets tubes. The validated lower limit of quantification was 10 ng/ml. The inter- and intra-run coefficients of variation (CV) for the assay were <12.9% and the accuracy were from -9.0 to -1.2%. AVE6971 was stable in WBC for at least 1 month at -75 degrees C. This assay proved to be suitable for the determination of AVE6971 in WBC from clinical studies.     

Oral bioavailability of active principles from herbal products in humans. A study on Hypericum perforatum extracts using the soft gelatin capsule technology.

The oral absorption of two known active principles of Hypericum perforatum, namely hyperforin and hypericin, was studied in an open, single dose, two-way, randomized, cross-over study involving 12 healthy subjects (six males and six females). Alcoholic Hypericum extract (300 mg, containing 5% hyperforin and 0.3 % hypericin) was administered in the morning after 12 hours fasting. The formulation was administered as softgel capsules containing, inter alia, soya oil together with the herbal extract. A second standard formulation in two piece hard gelatin capsules was also used for comparison purposes. Blood was sampled from the subjects at different times after drug administration and the plasma was analysed according to published analytical methods for the determination of hyperforin and hypericin. Peaks of plasma concentration, Cmax of hyperforin were 168.35 ng/ml +/- 57.79 for the soft gelatin formulation (CV=34.32, n=12) and 84.25 ng/ml +/- 33.51 for the hard gelatin capsule (CV=39.77, n=12). The Tmax values for hyperforin were 2.50 h +/- 0.83 for the soft gelatin formulation compared to 3.08 h +/- 0.79 for the reference formulation, whereas the total AUC were respectively 1482.7 h x ng/ml +/- 897.13 and 583.65 h x ng/ml +/- 240.29. As for hypericin, plasma levels were detectable in approximately half of the subjects treated. However also in this case the soft gelatin capsules exhibited a higher individual absorption when compared with the corresponding data for the hard gelatin capsules.     

Rapid high-performance liquid chromatographic measurement of amisulpride in human plasma: application to manage acute intoxication

Amisulpride, a substituted benzamide derivative, is a second-generation (atypical) antipsychotic and is effective as maintenance therapy in patients with schizophrenia. For toxicological purpose, a rapid RP-HPLC assay was developed for the determination of amisulpride in human plasma. A linear response was observed over the concentration range 100-1000 ng/ml. A good accuracy (< or =5%) was achieved for all quality controls, with intra- and inter-day variation coefficients equal or inferior to 4.9%. The lower limit of quantification was 20 ng/ml, without interferences of endogenous components. This rapid method (run time <5 min) was used to monitor eight intoxications involving amisulpride.     

A developed determination of midazolam and 1'-hydroxymidazolam in plasma by liquid chromatography-mass spectrometry: application of human pharmacokinetic study for measurement of CYP3A activity

This paper describes sensitive and reliable determination of midazolam (MDZ) and its major metabolite 1'-hydroxymidazolam (1-OHMDZ) in human plasma by liquid chromatography-mass spectrometry (LC-MS) with a sonic spray ionization (SSI) interface. MDZ, 1-OHMDZ and diazepam as an internal standard were extracted from 1ml of alkalinized plasma using n-hexane-chloroform (70:30, v/v). The extract was injected into an analytical column (YMC-Pak Pro C(18), 50mmx2.0mmi.d.). The mobile phase for separation consisted of 10mM ammonium acetate and methanol (50:50, v/v) and was delivered at a flow-rate of 0.2ml/min. The drift voltage was 100V. The sampling aperture was heated at 120 degrees C and the shield temperature was 260 degrees C. The total time for chromatographic separation was less than 16min. The validated concentration ranges of this method were 0.25-50ng/ml for both MDZ and 1-OHMDZ. Mean recoveries were 93.6% for MDZ and 86.6% for 1-OHMDZ. Intra- and inter-day coefficient variations were less than 6.5 and 5.5% for MDZ, and 6.1 and 5.7% for 1-OHMDZ at 0.3, 4, 20 and 40ng/ml. The limits of quantification were 0.25ng/ml for both MDZ and 1-OHMDZ. This method was sensitive and reliable enough for pharmacokinetic studies on healthy volunteers, and was applied for the measurement of CYP3A activity in humans after an intravenous (1mg) and a single-oral administration (2mg) of subtherapeutic MDZ dose.     

Simultaneous determination of myristyl nicotinate, nicotinic acid, and nicotinamide in rabbit plasma by liquid chromatography-tandem mass spectrometry using methyl ethyl ketone as a deproteinization solvent

Myristyl nicotinate (Nia-114) is an ester prodrug being developed for delivery of nicotinic acid (NIC) into the skin for prevention of actinic keratosis and its progression to skin cancer. To facilitate dermal studies of Nia-114, a novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method using methyl ethyl ketone (MEK) as a deproteinization solvent was developed and validated for the simultaneous determination of Nia-114, NIC, and nicotinamide (NAM) in rabbit plasma. NAM is the principal metabolite of NIC, which is also expected to have chemopreventive properties. The analytes were chromatographically separated using a Spherisorb Cyano column under isocratic conditions, and detected by multiple reaction monitoring (MRM) in positive-ion electrospray ionization mode with a run time of 9 min. The method utilized a plasma sample volume of 0.2 ml and isotope-labeled D4 forms of each analyte as internal standards. The method was linear over the concentration range of 2-1000, 8-1000, and 75-1000 ng/ml, for Nia-114, NIC, and NAM, respectively. The intra- and inter-day assay accuracy and precision were within +/-15% for all analytes at low, medium, and high quality control standard levels. The relatively high value for the lower limit of quantitation (LLOQ) of NAM was demonstrated to be due to the high level of endogenous NAM in the rabbit plasma (about 350 ng/ml). Endogenous levels of NIC and NAM in human, dog, rat, and mouse plasma were also determined, and mean values ranged from <2 ng/ml NIC and 38.3 ng/ml NAM in human, to 233 ng/ml NIC and 622 ng/ml NAM in mouse. Nia-114 was generally unstable in rabbit plasma, as evidenced by loss of 44-50% at room temperature by 2 h, and loss of 64-70% upon storage at -20 degrees C for 1 week, whereas it was stable (<7% loss) upon storage at -80 degrees C for 1 month.     

Simultaneous determination of piroxicam, meloxicam and tenoxicam in human plasma by liquid chromatography with tandem mass spectrometry

A rapid, sensitive and selective liquid chromatography-tandem mass spectrometric (LC-MS/MS) method for the determination of piroxicam, meloxicam and tenoxicam in human plasma was developed. Piroxicam, meloxicam, tenoxicam and isoxicam (internal standard) were extracted from human plasma with ethyl acetate at acidic pH and analyzed on a Sunfire column with the mobile phase of methanol:ammonium formate (15 mM, pH 3.0) (60:40, v/v). The analytes were detected using a mass spectrometer, equipped with electrospray ion source. The instrument was set in the multiple-reaction-monitoring (MRM) mode. The standard curve was linear (r=1.000) over the concentration range of 0.50-200 ng/ml. The coefficient of variation (CV) and relative error (RE) for intra- and inter-assay statistics at three QC levels were 1.0-5.4% and -5.9 to 2.8%, respectively. The recoveries of piroxicam, meloxicam and tenoxicam ranged from 78.3 to 87.1%, with that of isoxicam being 59.7%. The lower limit of quantification for piroxicam, meloxicam and tenoxicam was 0.50 ng/ml using a 100 microl plasma sample. This method was successfully applied to a pharmacokinetic study of piroxicam after application of transdermal piroxicam patches to humans.     

Determination of ragaglitazar,a novel dual acting peroxisome proliferator-activated receptor (PPAR) alpha and -gamma agonist,in human plasma by high-performance liquid chromatography coupled with tandem mass spectrometry

A sensitive and specific LC/MS/MS method has been developed and validated for determination of ragaglitazar (NNC 61-0029 or DRF 2725) in human plasma. After solid-phase extraction (SPEC((R)) PLUS C(8)) of plasma, separation was performed on a Symmetry Shield RP8 column (mobile phase: acetonitrile: 10 mM ammonium acetate, pH 5.6 (40:60 v/v)). Two ranges were validated having LLOQs of either 0.500 or 100 ng/ml and linearity up to either 500 or 50000 ng/ml. The intra-assay precision and accuracy were 1.1% to 15.7% and 85.8% to 118.2% (range 0.500-500 ng/ml) and 2.0% to 8.8% and 92.9% to 104.8% (range 100-50000 ng/ml). The method was applied for determination of ragaglitazar in plasma from phase 1 and 2 clinical studies.     

Liquid chromatography-mass spectrometry method for determination of tetramethylpyrazine and its metabolite in dog plasma

A liquid chromatography-mass spectrometry method is described for the determination of tetramethylpyrazine (TMP) and its active metabolite, 2-hydroxymethyl-3,5,6-trimethylpyrazine (HTMP) in dog plasma. This method involves a plasma clean-up step using protein precipitation procedure followed by LC separation and positive electrospray ionization mass spectrometry detection (ESI-MS). Chromatographic separation of the analytes was achieved on a C18 column using a mobile phase of methanol, water and acetic acid (50:50:0.6, v/v/v) at a flow rate of 1.0 ml/min. Selected ion monitoring (SIM) mode was used for analyte quantitation at m/z 137.2 for TMP, m/z 153.2 for HTMP and m/z 195.2 for caffeine. The linearity was obtained over the concentration ranges of 20-6000 ng/ml for TMP and 20-4000 ng/ml for HTMP and the lower limit of quantitation was 20 ng/ml for both analytes. For each level of QC samples, both inter- and intra-day precisions (R.S.D.) were 相似文献   

Sensitive quantification of ranolazine in human plasma by liquid chromatography--tandem mass spectrometry with positive electrospray ionization

A rapid, selective and sensitive liquid chromatography-tandem mass spectrometry (LC-MS-MS) method with positive electrospray ionization (ESI) was developed for the quantification of ranolazine in human plasma. After liquid-liquid extraction of ranolazine and internal standard (ISTD) phenoprolamine from a 100 microl specimen of plasma, HPLC separation was achieved on a Nova-Pak C(18) column, using acetonitrile-water-formic acid-10% n-butylamine (70:30:0.5:0.08, v/v/v/v) as the mobile phase. The mass spectrometer was operated in multiple reaction monitoring (MRM) mode using the transition m/z 428.5-->m/z 279.1 for ranolazine and m/z 344.3-->m/z 165.1 for the internal standard, respectively. Linear calibration curves were obtained in the concentration range of 5-4000 ng/ml, with a lower limit of quantitation (LLOQ) of 5 ng/ml. The intra- and inter-day precision values were below 3.7% and accuracy was within +/-3.2% at all three quality control (QC) levels. This method was found suitable for the analysis of plasma samples collected during the phase I pharmacokinetic studies of ranolazine performed in 28 healthy volunteers after single oral doses from 200 mg to 800 mg.     

Specific,sensitive and accurate liquid chromatographic-tandem mass spectrometric method for the measurement of ribavirin in rat and monkey plasma

Ribavirin is a purine nucleoside analog with broad spectrum activity against a spectrum of DNA and RNA viruses. To facilitate pharmacokinetics studies, a LC-MS-MS method for the analysis of ribavirin in rat and monkey plasma was developed and validated. The method involved the addition of acyclovir as an internal standard and protein precipitation with acetonitrile followed by separation by an Intertsil Silica column and quantification by a MS-MS equipped with a positive electrospray ionization in the multiple reaction monitoring mode. The MS-MS reaction was selected to monitor the 245-->113 and 226-->152 transitions for ribavirin and internal standard, respectively. The calibration curve was linear over a concentration range of 10-5000 ng/ml. The lower limit of quantitation was 10 ng/ml, the coefficient of variation (CV) was 8-11%, and the bias was 1-3%. Intra-day and inter-day analysis of QC samples at 30, 1500 and 3500 ng/ml indicate that the method was precise (CV<18%) and accurate (bias<13%). Ribavirin in rat and monkey plasma was stable at 5 degrees C for at least 24 h, 0 degrees C for at least 4 h, and after three freeze-thaw cycles. This specific, accurate and precise assay is useful in the study of the pharmacokinetics of this compound.     

Determination of perospirone by liquid chromatography/electrospray mass spectrometry: application to a pharmacokinetic study in healthy Chinese volunteers

Perospirone is a novel atypical antipsychotic with a unique combination of 5-HT(1A) receptor agonism as well as 5-HT(2A) and D(2) receptor antagonism. A simple rapid and selective LC-MS method utilizing a single quadrupole mass spectrometer was developed and validated for the determination of perospirone hydrochloride in human plasma. N-hexane was used to extract perospirone hydrochloride and amlodipine benzenesulfonate (internal standard (IS)) from an alkaline plasma sample. LC separation was performed on a XTerra MS C(18) column (100mmx2.1mm, i.d. 3.5microm) using methanol -10mM ammonium acetate (84:16, v/v) as a mobile phase. The quantification of target compounds was obtained by using a selected ion monitoring (SIM) at m/z 427.5 [M+H](+) for perospirone hydrochloride, and at m/z 431.4 [M+Na](+) for IS (amlodipine benzenesulfonate). Perospirone and IS eluted as sharp, symmetrical peaks with retention times of 3.11+/-0.01min and 4.15+/-0.2min, respectively. Calibration curves of perospirone hydrochloride in human plasma at concentrations ranging from 0.10 to 21.1ng/mL exhibited excellent linearity (r(2)=0.9997). The mean absolute recovery of the drug from plasma was more than 85%. Intra- and inter-day relative standard deviations were less than 6.43% and 11.9% for perospirone hydrochloride at the range from 0.32 to 10.6ng/mL. Stability characteristics of the drug-containing plasma were thoroughly evaluated to establish appropriate conditions to process, store and prepare for chromatographic analysis without inducing significant chemical degradation. The following pharmacokinetic parameters were elucidated after administering a single dose of 8mg perospirone hydrochloride. The area under the plasma concentration versus time curve from time 0 to 24h (AUC(0-24)) was 15.48+/-4.23microg/Lh; peak plasma concentration (C(max)) was 2.79+/-0.78microg/L; time to C(max) (T(max)) was 1.79+/-0.45h; and elimination half-life (t(1/2)) 6.78+/-1.38h. The described assay method showed acceptable precision, accuracy, linearity, stability, and specificity and can be used for pharmacokinetic studies, therapeutic drug monitoring, and drug abuse screening.