Validation of an analytical LC-MS/MS method in human plasma for the pharmacokinetic study of atomoxetine

This study aimed to validate a sensitive and reliable analytical method for the pharmacokinetic study of atomoxetine in human plasma by liquid chromatography-electrospray ionization-tandem mass spectrometry. Metoprolol was used as an internal standard. After liquid-liquid extraction with methyl t-butyl ether, the supernatant was evaporated. The residue was then reconstituted and an aliquot was injected into the high performance liquid chromatographic system. Separation was performed on a Phenomenex Luna C₁₈ column (2.0 mm × 100 mm, 3 μm particles) with a mobile phase of 10 mM ammonium formate buffer: methanol = 10: 90 (v/v). Tandem mass spectrometry was performed in the electrospray ionization positive ion mode using the multiple reaction monitoring mode for quantification. The mass transition pairs of m/z 256 → 44 for atomoxetine and m/z 268 → 116 for the internal standard were used. The flow rate of the mobile phase was 0.25 mL/min and the retention times of atomoxetine and the internal standard were found to be 1.0 and 0.9 min, respectively. The calibration curve for atomoxetine was linear in the concentration range of 1–750 ng/mL (r ² = 0.9992) with a lower limit of quantification of 1 ng/mL. The mean accuracy for atomoxetine was 93–102%. The coefficients of variation (precision) in the intra- and inter-day validation for atomoxetine were 4.0–6.8 and 1.1–9.6%, respectively. The pharmacokinetic parameters of atomoxetine were evaluated after administration of a 40-mg single oral dose to twelve healthy male volunteers. The mean AUC_{0–24 h}, C _max, T _max and T _1/2 for atomoxetine were 1.9 ± 0.8 μg h/mL, 0.34 ± 0.11 μg/mL, 1.0 ± 0.5 h and 3.9 ± 1.3 h, respectively.     

High-performance liquid chromatographic method for the determination of mangiferin in rat plasma and urine

A reversed-phase high-performance liquid chromatography assay for mangiferin in rat plasma and urine was developed. Rutin was employed as an internal standard. The mobile phase consisted of acetonitrile-water (16:84, v/v) containing 3% acetic acid at a flow rate of 1 mL/min. Detection was at 257 and 365 nm for mangiferin in plasma and urine, respectively. The limit of quantitation (LOQ) of mangiferin was 0.6 microg/mL in plasma, and 0.48 microg/mL in urine. The standard curve was linear from 0.6 to 24 microg/mL in plasma, and 0.48 to 24 microg/mL in urine, both intra- and inter-day precision of the mangiferin were determined and their RSD did not exceed 10%. The method provides a technique for rapid analysis of mangiferin in rat plasma and urine, which can be used in pharmacokinetic studies.     

Simultaneous determination of thirteen main components and identification of eight major metabolites in Xuebijing Injection by UPLC/Q-TOF

An ultra performance liquid chromatographic method was used for the simultaneous identification and quantification of thirteen main components in Xuebijing Injection, including uridine, gallic acid, guanosine, danshensu, protocatechualdehyde, oxypaeoniflorin, hydroxysafflor yellow A, paeoniflorin, ferulic acid, safflor yellow A, senkyunolide I, senkyunolide H and salvianolic acid B. The chromatographic separation was performed on an Acquity UPLC BEH C₁₈ column (1.7-μm, 2.1 × 100 mm, i.d.) with a gradient elution of acetonitrile and 0.2% acetic acid at a flow rate of 0.4 mL/min. The method was validated for linearity (r ² > 0.9990), intra- and inter-day precision (RSD < 1.94%), accuracy (91.8–99.7%), recovery (96.8–103.8%), limits of detection (0.16–8.0 ng), and limits of quantification (0.54–26.8 ng). At least eight metabolites in prototype were found in rat plasma and urine after intravenous injection of 4 mL/kg doses of Xuebijing Injection. The proposed method could be utilized to qualify and control Xuebijing Injection to ensure its safety and efficacy in application.     

Simultaneous quantitative determination of insulin aspart and insulin degludec in human plasma using simple shoot LC method

Combining short-acting and long-acting insulin analogs was a real challenge that was overcome by NovoNordisk through the co-formulation of insulin aspart and insulin degludec in single-dosage form. The proposed study provides a simple, short, and reliable HPLC method with diode array detection that is developed and validated for the simultaneous determination of insulin aspart and insulin degludec in human plasma. The proposed method achieved good separation between the two analytes utilizing a C8 column at 35°C in a very short run time (6 min), with a simple, low-cost, and reliable extraction method through precipitation of plasma protein. Gradient elution was applied using a mobile phase consisting of 0.1 M sodium sulfate (pH 3.4) and acetonitrile. The method was validated according to EMA Guideline on Bioanalytical Validation. The proposed method had a linear range from 3.0 to 300 μg/mL for insulin aspart and from 3.5 to 300 μg/mL for insulin degludec. The intra- and inter-day precision of insulin aspart were 0.36–3.33% and 1.59–8.84%, respectively, and accuracy was between 10.06 and 3.09% The intra- and inter-day precision of insulin degludec were 0.29–1.93% and 0.89–5.14%, respectively, and accuracy was between −5.29 and 3.91%.     

Determination of guaifenesin from spiked human plasma using RP-HPLC with UV detection

A rapid, simple, selective and specific high performance liquid chromatography (HPLC) method with UV detection (230 nm) was developed and validated for estimation of guaifenesin from spiked human plasma. The analyte and internal standard (eplerenone) were extracted with dichloromethane. The chromatographic separation was performed on HiQSil C 18HS column (250 × 4.6 mm, 5 μm) with a mobile phase of methanol: water (60: 40%, v/v) at a flow rate of 1 mL/min. Guaifenesin was well resolved from plasma constituents and internal standard. The calibration curve was linear in the range of 100–3200 ng/mL. The heteroscedasticity was minimized by using weighted least square regression with weighing factor of 1/x. The intra- and inter-day % RSD was less than 15. Results of recovery studies prove the extraction efficiency. Stability data indicated that guaifenesin was stable in plasma after three freeze thaw cycles and upon storage at ?20°C for 30 days.     

A validated UPLC–MS/MS method for quantitative determination of a potent neuroprotective agent Sarsasapogenin-AA13 in rat plasma: Application to pharmacokinetic studies

Sarsasapogenin-AA13(AA13), a sarsasapogenin derivative, exhibited good neuroprotective and anti-inflammatory activities in vitro and therapeutic effects on learning and memory dysfunction in amyloid-β-injected mice. A sensitive UPLC–MS/MS method was developed and validated to quantitatively determine AA13 in rat plasma and was further applied to evaluate the pharmacokinetic behaviour of AA13 in rats that were administered AA13 intravenously and orally. This method was validated to exhibit excellent linearity in the concentration range of 1–1000 ng/mL. The lower limit of quantification was 1 ng/mL for AA13 in rat plasma. Intra-day accuracy for AA13 was in the range of 90–114%, and inter-day accuracy was in the range of 97–103 %. The relative standard deviation of intra-day and inter-day assay was less than 15%. After a single oral administration of AA13 at the dose of 25 mg/kg, C_max of AA13 was 1266.4 ± 316.1 ng/mL. AUC_{0–48 h} was 6928.5 ± 1990.1 h·ng/mL, and t_1/2 was 10.2 ± 0.8 h. Under intravenous administration of AA13 at a dosage of 250 μg/kg, AUC_{0–48 h} was 785.7 ± 103.3 h⋅ng/mL, and t_1/2 was 20.8 ± 7.2 h. Based on the results, oral bioavailability (F %) of AA13 in rats at 25 mg/kg was 8.82 %.     

Development and validation of a reliable high-performance liquid chromatographic method for determination of nodakenin in rat plasma and its application to pharmacokinetic study

A simple and reliable high-performance liquid chromatographic (HPLC) method has been developed for the determination of nodakenin in rat plasma. The concentration of nodakenin was determined in plasma samples after deproteinization with methanol using hesperidin as internal standard. HPLC analysis was performed on a Diamonsil C(18) analytical column using acetonitrile-water (25:75, v/v) as the mobile phase and a UV detection at 330 nm. This method was validated in terms of recovery, linearity, accuracy and precision (intra- and inter-day variation). The extraction recoveries were 91.3 ± 10, 87.8 ± 4.8 and 92.6 ± 5.1 at concentrations of 0.500, 5.00 and 40.0 μg/mL, respectively. The standard curve for nodakenin was linear (r(2) ≥ 0.99) over the concentration range 0.250-50.0 μg/mL with a lower limit of quantification of 0.250 μg/mL. The intra- and inter-day precision (relative standard deviation, RSD) values were not higher than 12% and the accuracy (relative error, RE) was within ± 5.8% at three quality control levels. The validated method was successfully applied for the evaluation of the pharmacokinetics of nodakenin in rats after oral administration of Rhizoma et Radix Notopterygii decoction and nodakenin solution.     

HPLC assay method for ceftibuten in plasma and its application to pharmacokinetic study

The purpose of this study was to validate a reliable analytical method for pharmacokinetic study of ceftibuten in human plasma by high performance liquid chromatography (HPLC) system with UV detection. Ceftizoxime was used as the internal standard. After plasma sample was precipitated with acetonitrile and dichloromethane, the supernatant was directly injected into the HPLC system. Separation was performed on a Capcell Pak C₁₈ UG120 column (4.6 mm × 250 mm, 5 μm particles) with a mobile phase of acetonitrile/50 mM ammonium acetate (5: 95, v/v) and UV detection at a wavelength of 262 nm. The intra- and inter-day precision expressed as the relative standard deviation was less than 15%. The lower limit of quantification was 0.5 hg/mL of ceftibuten using 0.5 mL of plasma. The calibration curve was linear in concentration range of 0.5–30 μg/mL (r ² = 0.9998). The mean accuracy was 96–102%. The coefficient of variation (precision) in the intra- and inter-day validation was 0.9–3.9 and 0.9–2.4%, respectively. The pharmacokinetics of ceftibuten was evaluated after a single oral administration of 400 mg to healthy volunteers. The AUC_{0–9 h}, c _max, T _max, and T _1/2 were 86.6 ± 12.7 μg h/mL, 18.4 ± 1.5 μg/mL, 2.63 ± 0.83 and 2.65 ± 0.41 h, respectively. The method was demonstrated to be highly reproducible and feasible for pharmacokinetic studies of ceftibuten in eight volunteers after oral administration (400 mg as ceftibuten).     

Simultaneous determination of 10 kinds of biogenic amines in rat plasma using high‐performance liquid chromatography coupled with fluorescence detection

We describe a simple, rapid, selective and sensitive HPLC method coupled with fluorescence detection for simultaneous determination of 10 kinds of biogenic amines (BAs: tryptamine, 2‐phenethylamine, putrescine, cadaverine, histamine, 5‐hydroxytryptamine, tyramine, spermidine, dopamine and spermine). BAs and IS were derivated with dansyl chloride. Fluorescence detection (λ_ex/λ_em = 340/510 nm) was used. A satisfactory result for method validation was obtained. The assay was shown to be linear over the ranges 0.005–1.0 μg/mL for tryptamine, 2‐phenethylamine and spermidine, 0.025–1.0 μg/mL for putrescine, 0.001–1.0 μg/mL for cadaverine, 0.25–20 μg/mL for histamine, 0.25–10 μg/mL for 5–hydroxytryptamine and dopamine, and 0.01–1.0 μg/mL for tyramine and spermine. The limits of detection and the limits of quantification were 0.3–75.0 ng/mL and 1.0–250.0 ng/mL, respectively. Relative standard deviations were ≤5.14% for intra‐day and ≤6.58% for inter‐day precision. The recoveries of BAs ranged from 79.11 to 114.26% after spiking standard solutions of BAs into a sample at three levels. Seven kinds of BAs were found in rat plasma, and the mean values of tryptamine, 2‐phenethylamine, putrescine, cadaverine, histamine, spermidine and spermine determined were 52.72 ± 7.34, 11.45 ± 1.56, 162.56 ± 6.26, 312.75 ± 18.11, 1306.50 ± 116.16, 273.89 ± 26.41 and 41.51 ± 2.07 ng/mL, respectively.     

Application of an LC–ESI–QTOF–MS method for evaluating clindamycin concentrations in plasma and prostate microdialysate of rats

Clindamycin is used for infections caused by Gram-positive and Gram-negative anaerobic pathogens and Gram-positive aerobes. Propionibacterium acnes is an important opportunistic microorganism of the human skin and is related to prostatitis. An LC–electrospray ionization–quadrupole time-of-flight–MS method was validated for determining clindamycin concentrations in plasma and prostate microdialysate. Clindamycin separation was carried out on a C₁₈ column at 0.5 mL/min. The mobile phase employed gradient elution of formic acid and methanol. A mass spectrometer was operated in positive electrospray ionization mode to monitor ion 425.1784 and 253.1152 for clindamycin and cimetidine (internal standard), respectively. Linearity was obtained at 0.5–10.0 μg/mL (plasma) and 0.05–1.0 μg/mL (microdialysate) with coefficients of determination ≥0.999. The intra- and inter-day precision (coefficient of variation - CV%) values were ≤13.83% and 12.51% for plasma, respectively, and ≤10.90% and 9.35% for microdialysate, respectively. The accuracy was between 90.82% and 108.25% for plasma, and 96.97% and 106.98% for microdialysate. The present method was fully validated and applied to investigate clindamycin concentrations in both plasma and prostate by microdialysis in Wistar rats (80 mg/kg, intravenous). Because the penetration of antibiotics into the prostate may be restricted, this method allows us to investigate the prostate concentrations of clindamycin for the first time.     

Determination of metoprolol in human plasma and urine by high‐performance liquid chromatography with fluorescence detection

A simple, specific and sensitive HPLC method has been developed for the determination of metoprolol in human plasma and urine. Separation of metoprolol and atenolol (internal standard) was achieved on an Ace C₁₈ column (5 μm, 250 mm×4.6 mm id) using fluorescence detection with λ_ex=276 nm and λ_em=296 nm. The mobile phase consists of methanol–water (50:50, v/v) containing 0.1% TFA. The analysis was performed in less than 10 min with a flow rate of 1 mL/min. The assay was linear over the concentration range of 3 – 200 and 5 – 300 ng/mL for plasma and urine, respectively. The LOD were 1.0 and 1.5 ng/mL for plasma and urine, respectively. The LOQ were 3.0 and 5.0 ng/mL for plasma and urine, respectively. The extraction recoveries were found to be 95.6 ± 1.53 and 96.4 ± 1.75% for plasma and urine, respectively. Also, the method was successfully applied to three patients with hypertension who had been given an oral tablet of 100 mg metoprolol.     

Solid phase extraction for GC-FID determination of 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA) and methamphetamine (MA) in human urine

A simple solid phase extraction method was developed for estimating the amounts of 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA) and methamphetamine (MA) in urine by using the GC-FID technique. The urine sample was alkalinized prior to undergoing solid phase extraction using Oasis HLB®. A 5% methanol-water mixture containing 2% ammonium hydroxide was used for washing, whereas a 70% methanol-water mixture containing 2% acetic acid was used for elution. The compounds were analyzed using the standard GC-FID conditions previously established for ecstasy samples, i.e., column: CP-SIL 24 CB WCOT (30 m × 0.32 mm i.d., 0.25 μm film thickness); carrier gas: N₂ (2.6 mL/min); injector temperature: 290°C; detector temperature: 300°C; oven temperature: initial 80°C, final 270°C (1 min), ramp rate 20°C/min. Validation demonstrated the linearity of the calibration curves between 1 and 20 μg/mL (r > 0.99) for all analytes. The precisions (% RSD) were approximately 3–17%, 6–16% and 7–17% for MDMA, MDA and MA, respectively. The accuracies (% DEV) were (?)17-(+)5%, (?)18-(+)15% and (?)18-(+)0.6% for MDMA, MDA and MA, respectively. The recovery ranged from 80 to 107% and the lower limit of quantification (LLOQ) was 1 μg/mL. The method was successfully applied to determine the levels of these compounds in the urine of drug abuse suspects.     

Validation of a high-performance chromatographic method for determination of cefotaxime in biological samples

An analytical method for detecting and quantifying cefotaxime in plasma and several tissues is described. The method was developed and validated using plasma and tissues of rats. The samples were analyzed by reversed phase liquid chromatography (HPLC) with UV detection (254 nm). Calibration graphs showed a linear correlation (r > 0.999) over the concentration ranges of 0.5–200 μg/mL and 1.25–25 μg/g for plasma and tissues, respectively. The recovery of cefotaxime from plasma standards prepared at the concentrations of 25 μg/mL and 100 μg/mL was 98.5 ± 3.5% and 101.8 ± 2.2%, respectively. The recovery of cefotaxime from tissue standards of liver, fat and muscle, prepared at the concentration of 10 μg/g was: 89.8 ± 1.2% (liver), 103.9 ± 6.5% (fat) and 97.8 ± 2.1% (muscle). The detection (LOD) and quantitation (LOQ) limits for plasma samples were established at 0.11 μg/mL and 0.49 μg/mL, respectively. The values of these limits for tissues samples were approximately 2.5 times higher: 0.3 μg/g (LOD) and 1.25 μg/g (LOQ). For plasma samples, the deviation of the observed concentration from the nominal concentration was less than 5% and the coefficient of variation for within-day and between-day assays was less than 6% and 12%, respectively. The method was used in a pharmacokinetic study of cefotaxime in the rat and the mean values of the pharmacokinetic parameters are given.     

Determination of calycosin-7-O-beta-D-glucopyranoside in rat plasma and urine by HPLC

A reversed-phase high-performance liquid chromatographic (HPLC) assay for calycosin-7-O-beta-D-glucopyranoside in rat plasma and urine with solid-phase extraction (SPE) was developed. Rutin was employed as an internal standard. The mobile phase consisted of acetonitrile-water (16:84, v/v) at a flow rate of 1.0 mL/min. Detection was set at 280 nm. The limit of quantitation of calycosin-7-O-beta-D-glucopyranoside was 0.2 microg/mL in both plasma and urine. The standard curve was linear from 0.2 to 10.0 microg/mL in plasma, and 0.2 to 5.0 microg/mL in urine. Both intra- and inter-day precision of the calycosin-7-O-beta-d-glucopyranoside were determined and their RSD did not exceed 10%. The method was successfully applied to the analysis of samples obtained from a basic pharmacokinetic study, in which calycosin-7-O-beta-d-glucopyranoside was administered orally to rats.     

A rapid and sensitive UPLC–MS/MS method for quantitative determination of arformoterol in rat plasma,lung and trachea tissues

A rapid and sensitive ultra-performance liquid chromatography-tandem mass spectrometry (UPLC–MS/MS) method was developed and fully validated for determination of arformoterol in rat plasma, lung and trachea tissues.     

LC Method for the Determination of Rhaponticin in Rat Plasma, Faeces and Urine for Application to Pharmacokinetic Studies

A simple liquid chromatography (LC) method has been developed and validated to determine rhaponticin in rat plasma, faeces and urine. Chromatographic separation was achieved through mobile phase consisting of acetonitrile and water at a flow rate of 1.0 mL min^?1. Rhaponticin was quantified using UV detection at 324 nm. The assay was linear over the concentration range of 50–4,000 ng mL^?1 for plasma, faeces and urine. The intra- and inter-day RSD were less than 10%. The plasma, faeces and urine rhaponticin levels were monitored in rats after oral administration. This simple LC method appears to be useful in the pharmacokinetic investigation of rhaponticin.     

A rapid HPLC–MS/MS method for determining busulfan in hemolytic samples from children with hematopoietic stem cell transplantation

A rapid and sensitive method for the quantitative detection of busulfan (BU) in children's hemolytic samples by HPLC–tandem mass spectrometry (MS/MS) was established. In this study, the sample preparation procedure involved a one-step protein precipitation with acetonitrile (ACN) solution, and the HPLC–MS/MS method used Hypersil GOLD C₁₈. The mobile phase consisted of 10 mM ammonium acetate solution (containing 0.1% formic acid) and ACN with a flow rate of 0.4 mL/min. Multiple reaction monitoring modes were used for quantitative analysis and the ion pairs of BU and BU-d8 were m/z 263.9 → 150.9 and 272.0 → 159.0, respectively. BU had a good linearity in the range of 0.01–10 μg mL⁻¹. The intra- and inter-day relative error was between –7.21% and 8.26%, and the coefficient of variation was less than 12.64%. The average extraction recovery rate in plasma samples was 99.76% ± 6.53%, and the matrix in normal plasma and hemolyzed plasma had no significant effect on the detection results. Normal and hemolytic samples could maintain good stability at 4, 25 and –40°C. As a result, this method is particularly suitable for determining BU in hemolytic samples from children with hematopoietic stem cell transplantation (HSCT), and this study provides the methodological basis for further research on the pharmacokinetics of BU in children with HSCT.     

Detection of catecholamine metabolites in urine based on ultra-high-performance liquid chromatography–tandem mass spectrometry

The excretion of neurotransmitter metabolites in normal individuals is of great significance for health monitoring. A rapid quantitative method was developed with ultra-performance liquid chromatography–tandem mass spectrometry. The method was further applied to determine catecholamine metabolites vanilymandelic acid (VMA), methoxy hydroxyphenyl glycol (MHPG), dihydroxy-phenyl acetic acid (DOPAC), and homovanillic acid (HVA) in the urine. The urine was collected from six healthy volunteers (20–22 years old) for 10 consecutive days. It was precolumn derivatized with dansyl chloride. Subsequently, the sample was analyzed using triple quadrupole mass spectrometry with an electrospray ion in positive and multireaction monitoring modes. The method was sensitive and repeatable with the recoveries 92.7–104.30%, limits of detection (LODs) 0.01–0.05 μg/mL, and coefficients no less than 0.9938. The excretion content of four target compounds in random urine samples was 0.20 ± 0.086 μg/mL (MHPG), 1.27 ± 1.24 μg/mL (VMA), 3.29 ± 1.36 μg/mL (HVA), and 1.13 ± 1.07 μg/mL (DOPAC). In the urine, the content of VMA, the metabolite of norepinephrine and adrenaline, was more than MHPG, and the content of HVA, the metabolite of dopamine, was more than DOPAC. This paper detected the levels of catecholamine metabolites and summarized the characteristics of excretion using random urine samples, which could provide valuable information for clinical practice.     

Quantitative and Qualitative Analysis of CKD-501, Lobeglitazone, in Human Plasma and Urine Using LC–MS/MS and Its Application to a Pharmacokinetic Study

A simple, rapid and sensitive LC–MS/MS method in positive ion mode was developed and validated to determine CKD-501, lobeglitazone, in human plasma and urine using glipizide as an internal standard (IS). Lobeglitazone is a novel thiazolidinedione (TZDs)-based peroxisome proliferator-activated receptor (PPAR) agonist, used for the management of type-2 diabetes. After mixing the IS, dissolved in acetonitrile, with a plasma or urine sample containing lobeglitazone, 10?μL of supernatant was injected into the LC–MS/MS system. Quantification was performed in the multiple reaction monitoring (MRM) mode using transition of 481.5?→?152.2 (m/z) for lobeglitazone and 446.1?→?321.2 (m/z) for the IS. The method showed good linearity over concentration ranges of 0.5–1,000?ng?mL^?1 for plasma and 0.2–250?ng?mL^?1 for urine (r ²?≥?0.9996). The mean percent extraction recovery of lobeglitazone was 90.8?% for plasma and 87.3?% for urine, while the recoveries of the IS were greater than 86.4?% for both. The intra-day and inter-day precision of plasma ranged from 1.1 to 3.7 and 2.5 to 3.3?% (RSD), respectively, and the intra- and inter-day precision of urine ranged from 1.5 to 2.7 and 3.2 to 3.5?%, respectively. This method is simple, sensitive, and applicable for the pharmacokinetic study of lobeglitazone in human plasma. Most of the urine concentrations of lobeglitazone were below the LLOQ because the lobeglitazone is extensively metabolized.