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Publications (5)7.83 Total impact

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    ABSTRACT: The aim of the study was to evaluate and compare the pharmacokinetics of lansoprazole (LPZ) and its main metabolites, 5′-hydroxy lansoprazole (HLPZ) and lansoprazole sulfone (LPZS), after single and multiple intravenous (i.v.) doses of LPZ in healthy Chinese subjects. Twelve subjects (six males and six females) were given a single dose of LPZ by i.v. infusion on day 1, and multiple doses from day 2 to day 6. Blood samples were collected at designated time points for analysis of plasma concentrations of LPZ, HLPZ and LPZS by an LC–MS/MS method. LPZ was generally well tolerated in healthy Chinese subjects. After single and multiple i.v. doses of 30 mg LPZ, the C max values of LPZ, HLPZ and LPZS were 1490 ± 290 and 1450 ± 280, 175 ± 71 and 154 ± 56, and 51.3 ± 82.9 and 74.1 ± 158.7 ng/mL, with the AUC0–t values 3280 ± 2550 and 4260 ± 3880, 381 ± 128 and 389 ± 111, and 389 ± 1204 and 700 ± 2255 ng h/mL, respectively. The t 1/2 and CL values of LPZ after single and multiple i.v. doses were 1.48 ± 1.03 and 2.19 ± 1.03 h, and 11.67 ± 4.49 and 9.56 ± 4.08 L/h, respectively. Compared with the pharmacokinetics of LPZ after a single dose, t 1/2 increased markedly, CL decreased significantly and AUC increased by over 20 % after multiple doses. The results indicated that there was drug accumulation of LPZ after multiple i.v. doses, and there was no gender-related difference in pharmacokinetics of LPZ and its two metabolites.
    European Journal of Drug Metabolism and Pharmacokinetics 12/2012; 38(3). DOI:10.1007/s13318-012-0115-8 · 1.31 Impact Factor
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    ABSTRACT: The purpose of this study was to elucidate the pharmacokinetics of terazosin enantiomers in healthy Chinese male subjects. After a single oral dose of 2-mg terazosin, the plasma concentrations of terazosin enantiomers were measured over the course of 48 h in 12 healthy subjects. The plasma concentrations of (+)-(R)-terazosin at all time points were higher than those of (-)-(S)-terazosin. The area under the plasma concentration-time curve (AUC(0-∞) ) and maximum plasma concentration of (+)-(R)-terazosin were significantly greater than those of the (-)-(S)-terazosin (P < 0.01, respectively). The R/S ratio of AUC(0-∞) of terazosin was 1.68. For the first time, it was proven that the pharmacokinetics of terazosin was stereoselective in healthy Chinese male subjects. Chirality, 2012.© 2012 Wiley Periodicals, Inc.
    Chirality 12/2012; 24(12). DOI:10.1002/chir.22095 · 1.72 Impact Factor
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    ABSTRACT: A sensitive and specific LC-MS/MS method for the simultaneous quantification of niacin (NA) and its three main metabolites nicotinamide (NAM), nicotinuric acid (NUA) and N-methyl-2-pyridone-5-carboxamide (2-Pyr) in human plasma has been developed and validated. Plasma samples (200 μL) were prepared by deproteinization with acetonitrile (500 μL), then the supernatant after centrifugation was evaporated and reconstituted. Chromatography was performed on a phenomenex synergi hydro-RP column with an isocratic elution of methanol-0.1% formic acid (5:95, v/v). The full separation of all analytes was achieved within 9 min. Multiple-reaction monitoring (MRM) using the fragmentation transitions of m/z 124.1 → 80.1, 123.1 → 80.0, 181.0 → 79.0 and 153.1 → 110.2 in positive electrospray ionization (ESI) mode was performed to quantify NA, NAM, NUA and 2-Pyr, respectively. The calibration curves were linear over the concentration range of 2.0-3000 ng/mL for NA and NUA, 10.0-1600 ng/mL for NAM and 50.0-5000 ng/mL for 2-Pyr. This method has been validated in accordance with the US FDA guidelines for bioanalytical method development and applied to the determination of NA and its three main metabolites in Chinese subjects following a single oral dose of niacin extended-release and simvastatin 1000 mg/20mg. In particular, because of the endogenous NAM and 2-Pyr in human plasma, the concentrations of NAM and 2-Pyr in human plasma after dosing were determined by subtracting blank values of them.
    Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 08/2012; 904:107-14. DOI:10.1016/j.jchromb.2012.07.030 · 2.69 Impact Factor
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    ABSTRACT: The aim of the study was to evaluate the pharmacokinetics (PK) of lansoprazole (LPZ) and its main metabolites 5'-hydroxy lansoprazole (HLPZ) and lansoprazole sulphone (LPZS) after single intravenous (i.v.) doses of LPZ in healthy Chinese subjects, and the relationship between the cytochrome P450 (CYP) 2C19 phenotypes and the plasma concentrations of LPZS at the time-points in the elimination phase of LPZ. Twelve subjects were given lansoprazole by i.v. infusion. Blood samples were collected at designated time points up to 24 h. Plasma concentrations of LPZ, HLPZ and LPZS were quantified by a selective and sensitive liquid chromatography-tandem mass spectrometric (LC-MS/MS) method. After single i.v. doses of 15, 30 and 60 mg LPZ, C(max) and area under the plasma concentration-time curve (AUC(0-t)) of LPZ were 725 ± 151, 1480 ± 190, 3130 ± 480 µg·L(-1) and 1690 ± 1210, 3630 ± 2530, 8080 ± 4550 µg·h·L(-1), respectively. LPZ was generally well tolerated in healthy Chinese subjects, and displayed linear PK in the range of 15-60 mg. There were significant differences in the elimination of LPZ and the formation of LPZS between the single CYP2C19 poor metabolizer (PM) and the CYP2C19 extensive metabolizers (EM). The concentration of LPZS at the time-points in the elimination phase of LPZ could be monitored for CYP2C19 phenotyping. As a probe drug for CYP2C19 phenotyping, LPZ for injection might be more suitable than LPZ oral formulations.
    Xenobiotica 05/2012; 42(11):1156-62. DOI:10.3109/00498254.2012.687119 · 2.10 Impact Factor
  • Guifen Qiang, Man Yang, Yanan Zhang
    Journal of Bioequivalence & Bioavailability 01/2011; 03(10). DOI:10.4172/jbb.1000091