Junchun Chen

Zhejiang University, Hang-hsien, Zhejiang Sheng, China

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Publications (6)9.14 Total impact

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    ABSTRACT: An economical, reproducible and automated online solid-phase extraction coupled with liquid chromatography-tandem mass spectrometry method was developed to quantify methylprednisolone in human plasma. The method was validated in terms of selectivity, precision/accuracy, process efficiency, stability, cartridge reproducibility and carryover studies. Sample pretreatment was performed by protein precipitation and elimination using methanol followed by water dilution. Then, the mixture was passed onto the HySphere C8 EC-SE online solid-phase extraction cartridge followed by the separation of the analytes on an Agilent Eclipse XDB column. Electrospray ionization in positive ion mode and multiple reaction monitoring were used to monitor the ion transitions at m/z 375.4/160.8 for methylprednisolone, and m/z 361.2/147.0 for prednisolone. The calibration curve ranged from 5.25 to 525 ng/mL. Meanwhile both the intra-day and inter-day precision values (relative standard deviation) were within 4.45%. The method which turns out to be less laborious, faster and lower consumable cost per sample has already been successfully applied to a pharmacokinetic study in which the oral administration of 16 mg methylprednisolone was conducted in Chinese volunteers. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
    Journal of chromatographic science 11/2014; · 0.79 Impact Factor
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    ABSTRACT: A simple, robust LC-MS/MS assay for quantifying cefuroxime in human plasma was developed. Cefuroxime and tazobactam, as internal standard (IS), were extracted from human plasma by methanol to precipitate protein. Separation was achieved on a Zorbax SB-Aq (4.6 × 250 mm, 5 μ m) column under isocratic conditions. The calibration curve was linear in the concentration range of 0.0525-21.0 μ g/mL (r = 0.9998). The accuracy was higher than 90.92%, while the intra- and interday precision were less than 6.26%. The extraction procedure provides recovery ranged from 89.44% to 92.32%, for both analyte and IS. Finally, the method was successfully applied to a bioequivalence study of a single 500 mg dose of cefuroxime axetil in 22 healthy Chinese male subjects under fasting condition. Bioequivalence was determined by calculating 90% Cls for the ratios of C max, AUC0-t , and AUC0-∞ values for the test and reference products, using logarithmic transformed data. The 90% Cls for the ratios of C max (91.4%~104.2%), AUC0-t (97.4%~110.9%), and AUC0-∞ (97.6%~111.1%) values were within the predetermined range. It was concluded that the two formulations (test for capsule, reference for tablet) analyzed were bioequivalent in terms of rate and extent of absorption and the method met the principle of quick and easy clinical analysis.
    Advances in Pharmacological Sciences 01/2014; 2014:981624.
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    ABSTRACT: An automated method (XLC-MS/MS) that uses online solid-phase extraction coupled with HPLC-tandem mass spectrometry was reported here for the first time to quantify amlodipine in human plasma. Automated pre-purification of plasma was performed using 10mm×2mm HySphere C8 EC-SE online solid-phase extraction cartridges. After being eluted from the cartridge, the analyte and the internal standard were separated by HPLC and detected by tandem mass spectrometry. Mass spectrometric detection was achieved in the multiple reaction monitoring mode using a quadrupole tandem mass spectrometer in the positive electrospray ionization mode. The XLC-MS/MS method was validated and yielded excellent specificity. The calibration curve ranged from 0.10 to 10.22ng/mL, and both the intra- and inter-day precision and accuracy values were within 8%. This method proved to be less laborious and was faster per analysis (high-throughput) than offline sample preparation methods. This method has been successfully applied in clinical pharmacokinetic and bioequivalence analyses.
    Journal of pharmaceutical and biomedical analysis 06/2012; 70:614-8. · 2.45 Impact Factor
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    ABSTRACT: Risperidone (RIS), an atypical antipsychotic drug, is used for the treatment of psychoses associated with schizophrenia and other psychiatric disorders in adult and pediatric populations. An oral dispersible tablet formulation of risperidone has been developed. This study was conducted to provide support for marketing authorization of this drug in China. This study was designed to compare the pharmacokinetic (PK) properties and bioavailability of 2 RIS formulations-the dispersible formulation (test) and a branded formulation (reference) in healthy male Chinese volunteers. This single-dose, randomized-sequence, open-label, 2-period crossover study involved 22 healthy male Chinese volunteers. Equal numbers of eligible participants were randomly assigned to receive either the test drug (2 mg) or the same dose of the reference formulation, followed by a 2-week washout period and administration of the alternate formulation. The study drugs were administered after a 10-hour overnight fast. Blood samples were collected before dosing and at 0.33, 0.67, 1, 1.5, 2, 3, 4, 5, 6, 8, 10, 12, 15, 24, 36, 48, 72, and 96 hours after dosing. Plasma concentrations of RIS and its active metabolite, 9-hydroxyrisperidone (9-OH-RIS), were measured using LC-MS/MS. The safety profile was evaluated by recording adverse events (AEs), assessed using physical examination including vital signs, spontaneous reporting, and clinical laboratory results. The 2 formulations were considered to have met the requirements for bioequivalence if the 90% CIs for the log-transformed C(max) and AUC values were within the predetermined ranges of 75% to 133% and 80% to 125%, respectively, according to the guidelines of the State Food and Drug Administration (SFDA) of China. All 22 volunteers (mean [SD] age, 22.2 [1.98] years; weight, 64.07 [5.93] kg; height, 173 [5] cm; and body mass index, 21.2 [1.67] kg/m(2)) that were enrolled completed the study. For RIS, the 90% CIs for the ratios of C(max), AUC(0-t), and AUC(0-∞) were 93.2% to 116.7%, 97.9% to 111.3%, and 98.0% to 111.6%, respectively. For 9-OH-RIS, the 90% CIs were 95.8% to 113.9%, 100.2% to 109.7%, and 100.5% to 110.3%, respectively. All values were within the predetermined bioequivalence range. Seven AEs were reported somnolence (4 subjects [9.1%]) and dizziness (3 subjects [6.8%]). All AEs were transient and considered mild by physicians. The test (dispersible) and reference tablets met the regulatory criteria for bioequivalence as defined by the SFDA. Both formulations were well tolerated. Chinese Clinical Trials registration number: ChiCTR-TRC-12001996.
    Clinical Therapeutics 05/2012; 34(6):1432-9. · 2.23 Impact Factor
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    ABSTRACT: Enoxaparin is a low-molecular-weight heparin (LMWH) indicated for antithrombosis. A branded formulation of subcutaneously administered enoxaparin has been available in China since 2000, and a generic formulation is being developed. In a literature search of the key term enoxaparin (publication years not restricted), no published data were identified regarding the pharmacokinetic profile of generic enoxaparin in Chinese subjects. The aim of this study was to determine the bioequivalence of generic (test) and branded (reference) formulations of enoxaparin 60 mg (6000 IU anti-Xa) SC in healthy subjects for the purpose of meeting regulatory requirements for marketing the generic formulation in China. Healthy Chinese male volunteers were eligible for this single-dose, randomized-sequence, open-label, 2-period crossover study. Participants were randomly assigned to receive the test and reference formulations of enoxaparin 60 mg SC injection (fasting state) in randomized order, with the 2 study periods separated by a 1-week washout period. For the assessment of anti-Xa and anti-IIa activities (surrogates used to describe the pharmacokinetic properties and bioavailability of LMWH), heparin clotting assay, and activated partial thromboplastin time (aPTT), blood samples were obtained before (hour 0; baseline) and at 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, 14, and 24 hours after study drug administration. The 2 formulations were to be considered bioequivalent if the 90% CIs for the logarithm-transformed values of C(max), T(max), AUC(0-t), and AUC(0-infinity) fell within the predetermined range of 80% to 125%. Tolerability was assessed by questioning subjects about symptoms of possible adverse events and using laboratory analysis (hematology, biochemistry, hepatic function tests, and urinalysis). Twenty-two subjects participated in the study (mean [SD] age, 21.10 [1.02] years [range, 19-23 years]; weight, 64.07 [5.93] kg [range, 54-75 kg]; and height, 173 [5] cm [range, 163-187 cm]). For anti-Xa activity, the 90% CIs of C(max), AUC(0-t), and AUC(0-infinity) were 100.4% to 106.7%, 100.7% to 105.8%, and 100.7% to 106.1%, respectively. Corresponding values for anti-IIa activity were 85.0% to 102.4%, 80.4% to 94.8%, and 80.1% to 96.0%. For the hepa-rin clotting assay, the values were 97.4% to 102.4%, 98.2% to 102.4%, and 96.0% to 102.7%; and for aPTT, values were 98.2% to 104.3%, 97.4% to 101.6%, and 93.4% to 117.4%. No adverse events were reported during the study. Based on the 90% CIs of anti-Xa and anti-IIa activities, heparin clotting assay results, and aPTT in these healthy Chinese male subjects, the test and reference formulations of enoxaparin 60 mg SC met the regulatory requirements for bio-equivalence. Both formulations were well tolerated.
    Clinical Therapeutics 08/2009; 31(7):1559-67. · 2.23 Impact Factor
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    ABSTRACT: A simple and rapid LC–MS–MS assay was developed and validated for the quantitative determination of pitavastatin in human plasma. Sample pretreatment involved simple protein precipitation by addition of acetonitrile. Separation was on an Agilent 1.8μm Zorbax SB-C18 column (150mm×4.6mm) at 25°C using isocratic elution with methanol–0.1% formic acid in water (85:15, v/v) at a flow rate of 0.4mLmin−1. Detection was performed using electrospray ionization in positive ion multiple reaction monitoring mode by monitoring the ion transitions m/z 422.0→290.1 for pitavastatin, and m/z 330.1→192.1 for paroxetine (IS). LC–MS–MS was found to improve the quantitation of pitavastatin in plasma and was successfully applied in pharmacokinetic studies.
    Chromatographia 69(9):1041-1047. · 1.44 Impact Factor