Huili Zhou

Determination of amlodipine in human plasma using automated online solid-phase extraction HPLC–tandem mass spectrometry: Application to a bioequivalence study of Chinese volunteers

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 10 mm × 2 mm 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 10.22 ng/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.

Determination of risperidone in human plasma by HPLC-MS/MS and its application to a pharmacokinetic study in Chinese volunteers

This study presents a rapid, specific and sensitive liquid chromatography/tandem mass spectrometry (LC-MS/MS) assay for determination of risperidone (RIS) in human serum using paroxetine as an internal standard (IS). An Alltima-C18 column (2.1 mm×100 mm, 3 μm) and a mobile phase consisting of 0.1% formic acid-acetonitrile (40:60, v/v) were used for separation. The analysis was performed by selected reaction monitoring (SRM) method, and the peak area of the m/z 411.3→191.1 transition for RIS was measured versus that of the m/z 330.1→192.1 transition for IS to generate the standard curves. The assay linearity of RIS was confirmed over the range 0.25∼50.00 ng/ml and the limit of quantitation was 0.05 ng/ml. The linear range corresponds well with the serum concentrations of the analytes obtained in clinical pharmacokinetic studies. Intraday and interday relative standard deviations were 1.85%∼9.09% and 1.56%∼4.38%, respectively. The recovery of RIS from serum was in the range of 70.20%∼84.50%. The method was successfully applied to investigate the bioequivalence between two kinds of tablets (test versus reference products) in 18 healthy male Chinese volunteers. The result suggests that two formulations are bioequivalent.

Relative bioavailability and pharmacokinetic comparison of two different enteric formulations of omeprazole

In order to comply with the requirements for a drug listed in China, the study was developed to compare the pharmacokinetics and relative bioavailability of two different enteric formulations of omeprazole (OPZ) in healthy Chinese subjects. A total of 32 volunteers participated in the study. Plasma concentrations were analyzed by nonstereospecific liquid chromatography/tandem mass spectrometric (LC-MS/MS) method. After administration of a single 40-mg dose of the two OPZ formulations, the comparative bioavailability was assessed by calculating individual AUC0−t (the area under the concentration-time curve from time zero to the last measurable concentration), AUC0−∞ (the area under the concentration-time curve extrapolated to infinity), Cmax (the maximum observed concentration), and Tpeak (the time to Cmax) values of OPZ, 5-hydroxyomeprazole (OH-OPZ), and omeprazole sulfone (OPZ-SFN), respectively. The 90% confidence intervals (CIs) of AUC0−t, AUC0−∞, and Cmax were 85.4%–99.0%/88.8%–98.6%/87.6%–99.4%, 85.5%–99.2%/89.0%–98.6%/88.5%–101.3%, and 72.3%–87.6%/79.6%–91.1%/88.4%–99.1% for OPZ/OH-OPZ/OPZ-SFN, respectively, and Tpeak values did not differ significantly. In this study, the test formulation of OPZ in fasting healthy Chinese male volunteers met the Chinese bioequivalance standard to the reference formulation based on AUC, Cmax, and Tpeak.

A Phase I Study of the Safety and Pharmacokinetics of Higher-Dose Icotinib in Patients With Advanced Non-Small Cell Lung Cancer

Lessons Learned This phase I study evaluated the maximum tolerated dose, dose-limiting toxicities, safety, pharmacokinetics, and efficacy of icotinib with a starting dose of 250 mg in pretreated, advanced non-small cell lung cancer patients. We observed a maximum tolerated dose of 500 mg with a favorable pharmacokinetics profile and antitumor activity. These findings provide clinicians with evidence for application of higher-dose icotinib. Background. Icotinib, an oral epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, has shown favorable tolerability and antitumor activity at 100–200 mg in previous studies without reaching the maximum tolerated dose (MTD). In July 2011, icotinib was approved by the China Food and Drug Administration at a dose of 125 mg three times daily for the treatment of patients with locally advanced or metastatic non-small cell lung cancer (NSCLC) after failure of at least one platinum-based chemotherapy regimen. This study investigated the MTD, tolerability, and pharmacokinetics of higher-dose icotinib in patients with advanced NSCLC. Methods. Twenty-six patients with advanced NSCLC were treated at doses of 250–625 mg three times daily The EGFR mutation test was not mandatory in this study. Results. Twenty-four (92.3%) of 26 patients experienced at least one adverse event (AE); rash (61.5%), diarrhea (23.1%), and oral ulceration (11.5%) were most frequent AEs. Dose-limiting toxicities were seen in 2 of 6 patients in the 625-mg group, and the MTD was established at 500 mg. Icotinib was rapidly absorbed and eliminated. The amount of time that the drug was present at the maximum concentration in serum (Tmax) ranged from 1 to 3 hours (1.5–4 hours) after multiple doses. The t1/2 was similar after single- and multiple-dose administration (7.11 and 6.39 hours, respectively). A nonlinear relationship was observed between dose and drug exposure. Responses were seen in 6 (23.1%) patients, and 8 (30.8%) patients had stable disease. Conclusion. This study demonstrated that higher-dose icotinib was well-tolerated, with a MTD of 500 mg. Favorable antitumor activity and pharmacokinetic profile were observed in patients with heavily pretreated, advanced NSCLC.

An Economical Online Solid-Phase Extraction LC-MS/MS Method for Quantifying Methylprednisolone

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.

Safety and pharmacokinetics of dicloxacillin in healthy Chinese volunteers following single and multiple oral doses

Background Dicloxacillin, a semisynthetic isoxazolyl penicillin antibiotic, has antimicrobial activity against a wide variety of gram-positive bacteria including Staphylococcus aureus, Streptococcus pyogenes, Streptococcus pneumonia, Streptococcus epidermidis, Streptococcus viridans, Streptococcus agalactiae, and Neisseria meningitidis. The objective of this study was to evaluate the safety and pharmacokinetic profile of dicloxacillin after single and multiple oral dose in healthy Chinese volunteers. Methods A single-center, open-label, randomized, two-phase study was conducted in 16 subjects. In the single-dose phase, subjects were randomly assigned to receive single doses of 0.25, 0.5, 1.0, and 2.0 g of dicloxacillin sodium capsule in a 4-way crossover design with a 5-day washout period between administrations. In the multiple-dose phase, subjects were assigned to receive 0.25 or 0.5 g every 6 hours for 3 days in a 2-way crossover design. Plasma and urine pharmacokinetic samples were assayed by a validated high-performance liquid chromatography-tandem mass spectrometry method. Pharmacokinetic parameters were calculated and analyzed statistically. Safety assessments were conducted throughout the study. Results Following a single oral dose of 0.25–2.0 g dicloxacillin sodium, the maximum plasma drug concentration (Cmax) and the corresponding values for the area under the concentration– time curve from 0 to 10 hours (AUC0–10 h) increased in a dose-proportional manner. The mean elimination half-life (t1/2) was in the range of 1.38–1.71 hours. Dicloxacillin was excreted in its unchanged form via the kidney, with no tendency of accumulation, and varied from 38.65% to 50.10%. No appreciable accumulation of drug occurred with multiple oral doses of dicloxacillin. No serious adverse events were reported. Adverse events were generally mild. Conclusion Dicloxacillin was safe and well tolerated in the volunteers and displayed linear increases in the Cmax and AUC0–10 h values.

Optimization of solid phase extraction clean up and validation of quantitative determination of carbazochrome sodium sulfonate in human plasma by liquid chromatography-electrospray ionization tandem mass spectrometry.

A mixed-mode anion exchange solid phase extraction (SPE) method for extraction and clean up of carbazochrome sodium sulfonate (CSS) and (1S)-(+)-10-camphorsulfonic acid (IS) was optimized for quantification by high-performance liquid chromatography/negative electrospray ionization mass spectrometry. The analytes were extracted from 1mL of human plasma via SPE on Oasis(®) WAX cartridge. Chromatographic separation was achieved on a Zorbax SB-Aq (4.6×250mm, 5μm) column under an isocratic condition. Detection was performed using electrospray ionization in negative ion multiple reaction monitoring (MRM) mode. The deprotonated precursor to product ion transitions monitored for CSS and IS was at m/z 299.0→256.0 and m/z 230.9→79.8, respectively. The method was fully validated for its selectivity, sensitivity, precision, accuracy, recovery, matrix effect and stability. Linear range was 0.189-37.8ng/mL with a high square regression coefficient (r=0.9995). The intra-and inter-day precision (RSD, %) ranged from 0.95% to 4.17%, and the intra-and inter-day accuracy was between 95.03% and 105.9%. This method was successfully applied to a bioequivalence study of 90mg CSS formulation in 18 healthy Chinese male subjects under fasting condition.

Simple and Sensitive Analysis of Blonanserin and Blonanserin C in Human Plasma by Liquid Chromatography Tandem Mass Spectrometry and Its Application

A highly sensitive, simple, and rapid liquid chromatography tandem mass spectrometry method to simultaneously determine blonanserin and blonanserin C in human plasma with AD-5332 as internal standard (IS) was established. A simple direct protein precipitation method was used for the sample pretreatment, and chromatographic separation was performed on a Waters XBridge C8 (4.6 × 150 mm, 3.5 μm) column. The mobile phase consists of a mixture of 10 mM ammonium formate and 0.1% formic acid in water (A) and 0.1% formic acid in methanol (B). To quantify blonanserin, blonanserin C, and IS, multiple reaction monitoring (MRM) was performed in positive ESI mode. The calibration curve was linear in the concentration range of 0.012–5.78 ng·mL−1 for blonanserin and 0.023–11.57 ng·mL−1 for blonanserin C (r 2 > 0.9990). The intra- and interday precision of three quality control (QC) levels in plasma were less than 7.5%. Finally, the current simple, sensitive, and accurate LC-MS/MS method was successfully applied to investigate the pharmacokinetics of blonanserin and blonanserin C in healthy Chinese volunteers.

Pharmacokinetics and tolerability of febuxostat after oral administration in healthy Chinese volunteers: a randomized, open-label, singleand multiple-dose three-way crossover study.

OBJECTIVE Febuxostat is a novel non-purine selective inhibitor of xanthine oxidase indicated for the chronic management of hyperuricemia in patients with gout. The aim of the present study was to evaluate the pharmacokinetic properties and tolerability of single and multiple oral administrations of febuxostat capsules in healthy Chinese volunteers. METHODS This openlabel, single- and multiple-dose three-way crossover study was conducted in healthy Chinese volunteers. Subjects were randomized to receive a single dose of febuxostat 40, 80, or 120 mg in separate trial periods, with a 1-week washout between periods. Those allocated to the 40 mg and 80 mg dose continued into the multiple-dose phase, in which they received 40 mg or 80 mg once daily for 6 consecutive days. During the course of the study, blood samples were collected and the concentrations of febuxostat were determined using LC-MS/MS. Pharmacokinetic parameters were estimated using a noncompartmental model. Tolerability was determined using clinical evaluation and monitoring of adverse events (AEs). RESULTS 12 healthy Chinese volunteers were enrolled and completed 3 treatment periods. After oral administration of single doses of 40, 80, and 120 mg of febuxostat, the mean (SD) Cmax was 2,835.43 (1,136.41), 5,356.75 (1,711.33), and 7,718.21 (2,446.34) ng/mL, respectively; the AUC0-48h was 8,821.10 (3,018.35), 17,854.46 (5,113.28), and 30,832.05 (10,992.20) ng×h/ mL; the AUC0-∞ was 8,990.33 (3,046.14), 18,193.58 (5,160.80), and 31,466.93 (1,1074.74) ng×h/mL; the t1/2 was 5.95 (2.71), 9.41 (7.47), and 12.34 (10.34) hours; the Cl/F was 4.81 (1.18), 4.70 (1.21), and 4.18(1.19) L/h; and the Vz/F was 39.66 (16.69), 62.72 (51.41), and 73.41 (64.84) L. After administration of multiple doses of 40 and 80 mg febuxostat, the mean (SD) Cmax,ss was 2,762.38 (1,331.96) and 5,047.27 (1,456.57) ng/mL; the Cmin,ss was 124.10 (6.32) and 46.93 (15.86) ng/mL; the AUCss,0-τ was 8,525.49 (2,160.64) and 16,757.12 (4,223.17) ng×h /mL; the steadystate plasma concentration (Css) was 355.23 (90.03) and 698.21 (175.97) ng/mL; the t1/2 was 7.68 (3.30) and 11.33 (6.94) hours; the Cl/F was 4.99 (1.30) and 5.05 (1.22) L/h; and the Vz/F was 54.10 (24.10) and 85.51 (65.99) L. No serious AEs were reported, and there were no discontinuations due to AEs. CONCLUSION The PK of febuxostat exhibited dose proportional kinetics from 40 to 120 mg dose. After multiple doses, the pharmacokinetic parameters of febuxostat were consistent with those after single doses. There was no accumulation in febuxostat exposure in healthy Chinese between multiple doses and single dose. At the doses studied, febuxostat appeared to be well tolerated in these healthy volunteers.

Pharmacokinetics and safety of sitafloxacin after single oral doses in healthy volunteers.

OBJECTIVE Sitafloxacin is a new fluoroquinolone with a broad spectrum of antibacterial activity, including grampositive and gram-negative bacteria. This study was to evaluate the pharmacokinetic characteristics of a single dose of sitafloxacin in healthy Chinese volunteers. METHODS This was a single-center, open-label, randomized-sequence study conducted in 12 subjects. Subjects were randomly assigned to receive single doses of 50, 100, and 200 mg of sitafloxacin in a 3-way crossover design with a 7-day washout period between administrations. Quantification was carried out using a validated high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method. Pharmacokinetic parameters were calculated and analyzed statistically. Safety assessments were conducted throughout the study. RESULTS After administration of single doses of 50, 100, and 200 mg, geometric mean estimate for sitafloxacin Cmax were 0.72, 1.62, and 2.73 μg/mL and the mean of AUClast were 3.97, 8.71, and 18.03 μg x h/mL, respectively. Sitafloxacin was rapidly absorbed, reaching Cmax ranged from 0.85 to 1.21 hours. The terminal half-life ranged from 5.19 to 6.28 hours. The Cmax and AUC last were proportional to the doses. The mean clearance, the half-life, and the volume of distribution were constant, irrespective of the dose. CONCLUSION In healthy Chinese subjects, single dosing of sitafloxacin resulted in linear plasma pharmacokinetics.