Jingying Jia

Determination of melamine and cyanuric acid in human urine by a liquid chromatography tandem mass spectrometry.

Melamine was found to be the etiological factor for the urinary stones epidemic in infants and young children in China in 2008. Urine level of melamine and its analog cyanuric acid may be useful markers for the evaluation of toxic effects. Liquid chromatography tandem mass spectrometry methods for the individual determination of melamine and cyanuric acid in human urine are described. Using isotope labeled internal standards during liquid-liquid extraction, the method was fully validated by verifying specificity, linearity, LLOQ, intra- and inter-assay precision and accuracy, matrix effect, recovery and stability. Calibration curves with good linearity (r=0.9999) over the concentration range from 10 to 5000 ng/ml, intra-assay precision <10% and inter-assay precision <15%, accuracy between 93.0 and 111.6% were obtained with multiple reaction monitoring mode for melamine and cyanuric acid in human urine. The methods were successfully applied to the analysis of urine samples collected from 86 infants and 110 adults.

Pharmacokinetic study of melamine in rhesus monkey after a single oral administration of a tolerable daily intake dose.

To perform pharmacokinetic study of melamine in rhesus monkey, melamine was orally administered to three experimental monkeys at a single dose of 1.4 mg/kg body weight. Plasma and urine were collected for the determination of melamine and cyanuric acid with a liquid chromatography tandem mass spectrometry method. The mean+/-SD area under the concentration-time curve from time zero to 48 h (AUC0-t) was 14,145+/-2002 microg/Lh. The maximum concentration of melamine in plasma (C(max)) was 1767+/-252 microg/L. The time to maximum concentration (T(max)) was 2.67+/-1.16 h and the half-life of melamine in plasma (t(1/2)) was 4.41+/-0.43 h. Following oral administration, melamine was rapidly excreted, mainly through urinary clearance. No significant correlation was found between melamine and cyanuric acid, suggesting that cyanuric acid may not be derived from melamine.

Improved and simplified LC-ESI-MS/MS method for homocysteine determination in human plasma : Application to the study of cardiovascular diseases

A liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) method was developed and validated for the determination of human plasma homocysteine (Hcy), an important independent risk factor for cardiovascular disease, with a simplified sample pretreatment procedure and a zero blank free of endogenous Hcy for calibrator/QC preparation. Following protein precipitation, chromatographic separation was performed on Hypersil Aquasil C18 column (50 mm x 2.1mm, 5 microm, Thermo) using mobile phase of aqueous 10% methanol containing 0.02% formic acid at 0.25 mL/min. Hcy and deuterated internal standard were detected in the multiple reaction monitoring mode with precursor to product ion transitions of m/z 136.1/90.0 and 140.1/94.0, respectively. The retention time was 1.2 min, and the total run time was 2 min per injection. A streamlined three-point calibration curve and one-point QC was used. Excellent linearity was observed with correlation coefficient (r)>0.99. The intra- and inter-batch were < or =3.24% and < or =4.04%, and accuracy was within +/-10%. Method comparison between the proposed method (y) and FPIA assay (x) demonstrated a correlation equation of y=1.003x + 0.4318 (r=0.9589). The developed method, improved for automation with cost-effective reagents, was proven to be suitable for high-throughput quantitative determination of Hcy in clinical practice by successfully applying it to the cardiovascular disease study.

Therapeutic monitoring of serum digoxin for patients with heart failure using a rapid LC-MS/MS method

OBJECTIVE Here we develop a liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the determination of digoxin in serum. DESIGN AND METHODS The serum samples were extracted with methyl tert-butyl ether using an isotope-labeled digoxin-d3 as internal standard. The analyte was separated on a reverse phase Capcell C18 column and detected in positive electrospray ionization multiple reaction monitoring mass spectrometry. RESULTS The chromatographic analysis was carried out within 3 min, but the complete analysis took longer because of the liquid-liquid extraction. The lower limit of quantification was 0.1 ng/mL for digoxin. The intra- and inter-batch precisions were less than 12%, and the bias ranged from -9.1% to 10.7%. The external quality assessment (EQA) results obtained with the LC-MS/MS method were comparable to target values. Subsequently, this method has been applied to the therapeutic monitoring of digoxin in a clinical setting. CONCLUSION In this study, we have developed a rapid and reliable LC-MS/MS method for the therapeutic monitoring of digoxin in human serum.

Phase I study on the pharmacokinetics and tolerance of ZT-1, a prodrug of huperzine A, for the treatment of Alzheimer's disease

Aim:Huperzine A isolated from the Chinese herb Huperzia serrata (Thunb) Trev is a novel reversible and selective AChE inhibitor. The aim of this study was to evaluate the pharmacokinetics and tolerance of single and multiple doses of ZT-1, a novel analogue of huperzine A, in healthy Chinese subjects.Methods:This was a double-blinded, placebo-controlled, randomized, single- and multiple-dose study. For the single-dose study, 9 subjects were randomly divided into 3 groups receiving ZT-1 (0.5, 0.75 or 1 mg, po) according to a Three-way Latin Square Design. For the multiple-dose study, 9 subjects receiving ZT-1 (0.75 mg/d, po) for 8 consecutive days. In the tolerance study, 40 subjects were randomly divided into 5 groups receiving a single dose of ZT-1 (0.5, 0.75, 1, 1.25 or 1.5 mg, po). Plasma and urine concentrations of ZT-1 and Hup A were determined using LC-MS/MS. Pharmacokinetic parameters, including Cmax, AUC0–72 h and AUC0–∞ were calculated. Tolerance assessments were conducted throughout the study.Results:ZT-1 was rapidly absorbed and converted into huperzine A, thus the plasma and urine concentrations of ZT-1 were below the limit of quantification (<0.05 ng/mL). After single-dose administration of ZT-1, the mean tmax of huperzine A was 0.76–0.82 h; the AUC0–72 h and Cmax of huperzine A showed approximately dose-proportional increase over the dose range of 0.5–1 mg. After the multiple-dose administration of ZT-1, a steady-state level of huperzine A was achieved within 2 d. No serious adverse events were observed.Conclusion:ZT-1 is a pro-drug that is rapidly absorbed and converted into huperzine A, and ZT-1 is well tolerated in healthy Chinese volunteers.

Pharmacokinetics and Bioequivalence Evaluation of Two Different Atorvastatin Calcium 10-mg Tablets: A Single-Dose, Randomized-Sequence, Open-Label, Two-Period Crossover Study in Healthy Fasted Chinese Adult Males

BACKGROUND Atorvastatin calcium is a 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor indicated for the prevention of cardiovascular disease and for the treatment of dyslipidemia. Information on the pharmacokinetics of atorvastatin in a Chinese population is lacking, and regulatory requirements necessitate a bioequivalence study for the marketing of a generic product in China. OBJECTIVE The aim of the present study was to assess the pharmacokinetics and bioequivalence of a test and branded reference formulation of atorvastatin calcium 10-mg tablets in healthy fasted Chinese male volunteers. METHODS This was a single-dose, randomized-sequence, open-label, 2-period crossover study with a 2-week washout period between doses. Healthy Chinese males were randomly assigned to receive 20 mg of either the test or reference formulation, and 13 blood samples were obtained over a 48-hour interval. Plasma concentrations of parent atorvastatin and ortho-hydroxy-atorvastatin (primary active metabolite) were simultaneously determined using a validated liquid chromatography-isotopic dilution mass spectrometry method. Pharmacokinetic parameters, including C(max), T(max), t((1/2)), AUC(0-t), and AUC(0-infinity)), were calculated. The 2 formulations were to be considered bioequivalent if 90% CIs for the log transformed ratios of AUC and C(max) of atorvastatin were within the predetermined bioequivalence range (0.80-1.25 for AUC and 0.70-1.43 for C(max)) as established by the State Food and Drug Administration of China. Tolerability was evaluated throughout the study by vital signs monitoring, physical examinations, 12-lead ECGs, and subject interviews on adverse events (AEs). RESULTS A total of 66 subjects were assessed for inclusion; 20 were excluded prior to study initiation. Of the 46 healthy subjects (mean [SD] age, 24.1 [2.5] years; height, 170.8 [5.1] cm; weight, 64.6 [6.4] kg; body mass index (BMI), 22.1 [1.7] kg/m(2)) who completed the study, 45 subjects (mean [SD] age, 24.1 [2.5] years; height, 171.1 [4.9] cm; weight, 64.8 [6.3] kg; BMI, 22.1 [1.7] kg/m(2)) were included in the pharmacokinetic and bioequivalence analyses; 1 subject was excluded from these analyses because he mistakenly received the same formulation in both periods. No period or sequence effect was observed. The mean values of C(max), AUC(0-t), and AUC(0-infinity)) for the test and reference formulations of atorvastatin (8.78 and 10.76 ng/mL, 38.22 and 40.02 ng/mL/h, 42.73 and 44.51 ng/mL/h, respectively) and ortho-hydroxy-atorvastatin (5.78 and 5.77 ng/mL, 47.32 and 48.47 ng/mL/h, 52.36 and 53.14 ng/mL/h) were not significantly different. The 90% CIs for natural log-transformed ratios of C(max), AUC(0-t), and AUC(0-infinity)) of both atorvastatin (0.73-0.91, 0.92-1.02, and 0.91-1.01, respectively) and ortho-hydroxy-atorvastatin (0.83-1.05, 0.92-1.02, and 0.93-1.02) were within the bioequivalence acceptance limits. Three subjects (6.5%) reported a total of 4 mild AEs (1 abdominal discomfort and 3 venipuncture syncope), which were not considered to be associated with administration of the study drug. CONCLUSIONS This single-dose (20 mg) study found that the test and reference formulations of atorvastatin calcium 10-mg tablet met the regulatory definition for assuming bioequivalence in these healthy fasted Chinese male volunteers. Both formulations were generally well tolerated in the population studied. Chinese National Registry Code: 2007L02512.

Pharmacokinetics and bioequivalence evaluation of two formulations of 10-mg amlodipine besylate: An open-label, single-dose, randomized, two-way crossover study in healthy chinese male volunteers

BACKGROUND Amlodipine is a third-generation dihydropyridine calcium antagonist for the treatment of angina and hypertension. The relative bioavailability of a newly developed dispersible tablet as compared with an established branded formulation has not been reported in a Chinese population. OBJECTIVE The aim of this study was to assess and compare the pharmacokinetic properties, bioavailability, and bioequivalence of a newly developed dispersible tablet formulation of amlodipine besylate with those of an established branded formulation in healthy Chinese adult male volunteers. METHODS An open-label, single-dose, randomized, 2-way crossover study was conducted in fasted healthy Chinese male volunteers. Eligible participants were randomly assigned in a 1:1 ratio to receive 2 tablets (5 mg each) of the test or 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. Serum samples were collected over 120 hours. Amlodipine concentrations in the serum were analyzed by liquid chromatography tandem mass spectrometry with positive ion electrospray ionization using the multiple reaction monitoring mode. The visible detection of the method was in the range of 0.2 to 32.0 ng/mL, and the lower limit of quantification for amlodipine was 0.2 ng/mL. The amlodipine serum concentration-time curves were used to obtain pharmacokinetic parameters including AUC(0-t), AUC(0-infinity)), and C(max). The criteria for bioequivalence were 90% CIs of 80% to 125% for AUC and 70% to 143% for C(max), according to guidelines of the State Food and Drug Administration of the Peoples Republic of China. Tolerability was based on the recording of adverse events (AEs), monitoring vital signs, electrocardiograms, and clinical laboratory tests at baseline and completion of the study. RESULTS A total of 20 healthy Chinese male volunteers (mean [SD] age, 21.4 [2.6] years [range, 1926 years]; weight, 61.3 [5.4] kg [range, 54.0-75.0 kg]; and height, 171.2 [3.6] cm [range, 162.0-177.0 cm) were included in the study. The mean (SD) C(max), T(max), AUC(0-t), and AUC(0-infinity)) values after administration of the test and reference formulations, respectively, were as follows: 5.46 (1.13) versus 5.88 (1.24) ng/mL, 7.70 (2.08) versus 9.20 (4.18) hours, 284.56 (77.59) versus 311.34 (75.97) ng/mL/h, and 331.37 (111.03) versus 358.74 (101.10) ng/mL/h. The mean (SD) t(1/2) was 38.52 (10.51) hours for the test formulation and 38.75 (7.07) hours for the reference formulation. On analysis of variance, no period or sequence effects were observed for any pharmacokinetic property; however, a significant formulation effect was observed for C(max), AUC(0-t), and AUC(0-infinity)). The relative bioavailability of the test formulation was 90.9% by mean AUC(0-t) and 91.2% by mean AUC(0-infinity). The 90% CIs for the ratios of C(max), AUC(0-t), and AUC(0-infinity) were 88.4% to 97.5%, 86.4% to 95.7%, and 85.8% to 97.0%, respectively, meeting the predetermined criteria for bioequivalence. One subject (5%) reported 2 AEs. The AEs were mild, possibly associated with study drug, and resolved spontaneously by the next evaluation. No serious AEs were reported. CONCLUSIONS In this small study in healthy Chinese adult male volunteers, a single 10-mg dose of the dispersible tablet formulation (test) of amlodipine besylate met the regulatory criteria for bioequivalence to the established tablet formulation (reference) based on the rate and extent of absorption. Both formulations were well tolerated.

Liquid chromatography tandem mass spectrometry method for determination of N-acetylcysteine in human plasma using an isotope-labeled internal standard

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to determine total N-acetylcysteine in human plasma. Mass spectrometric detection was achieved in positive electrospray ionization and multiple reaction monitoring mode. The mass transition pairs of N-acetylcysteine and the isotope-labeled internal standard d3-N-acetylcysteine were 164 → 122 and 167 → 123, respectively. The method was linear over the range of 10-5000 ng/mL in human plasma. The adoption of trichloroacetic acid significantly enhanced the extraction recovery. The blank matrix was screened to minimize the influence of endogenous N-acetylcysteine. After being fully validated, the method was successfully applied to the pharmacokinetic and bioequivalent study of N-acetylcysteine after oral administration of 600 mg tablets to 24 healthy Chinese volunteers.

Liquid chromatography-tandem mass spectrometry method for determination of N-acetylglucosamine concentration in human plasma

A simple, reliable and sensitive liquid chromatography-tandem mass spectrometry method (LC-MS/MS) was developed and validated for quantification of N-acetylglucosamine in human plasma. Plasma samples were pretreated with acetonitrile for protein precipitation. The chromatographic separation was performed on Hypersil Silica column (150mmx2mm, 5microm). The deprotonated analyte ion was detected in negative ionization mode by multiple reaction monitoring mode. The mass transition pairs of m/z 220.3-->118.9 and m/z 226.4-->123.2 were used to detect N-acetylglucosamine and internal standard 13C6-N-acetylglucosamine, respectively. The assay exhibited a linear range from 20 to 1280ng/ml for N-acetylglucosamine in human plasma. Acceptable precision and accuracy were obtained for concentrations of the calibration standard and quality control. The validated method was successfully applied to analyze human plasma samples in a pharmacokinetic study.

Hair analysis, a reliable and non-invasive method to evaluate the contamination by clenbuterol.

The illegal use of clenbuterol has been an increasingly serious issue in todays livestock products industry. It becomes an important project to develop a reliable approach to detect its content in food animals. A simple and sensitive LC-MS/MS method was developed to detect clenbuterol residue in hair, with the low limit of quantitation (LLOQ) about 0.5ng/g. Hogs fed with 340µg/day of clenbuterol for 2 weeks were found a high clenbuterol residue in their hair approximately at 1-2 months after withdrawal. There remained 3.31ng/g clenbuterol in hog hair approximately 5 months after the last administration, focused on the tip of the hair (mainly in hogs with dark hair). An extensive contamination was observed in twenty investigated market hogs whose dark hair obviously had a higher clenbuterol residue than the light ones (p=0.017, t test). Volunteers (60.3 percent) from Xuhui district (Shanghai) were found to have a detectable amount of clenbuterol in their hair (>0.5ng/g). In conclusion, hair residue detection is a reliable method to evaluate the clenbuterol contamination in animals and humans. Meat supply in the Xuhui district might have serious potential safety risks which should be further investigated and discussed to determine the safety range of clenbuterol residue.