AIM　To assess the pharmacokinetic profile of single doses of meloxicam in healthy Chinese volunteers. METHODS　The plasma concentrations of meloxicam after an oral dose of 15 mg to twenty healthy male volunteers were analized by means of a validated HPLC method. The pharmacokinetic parameters were subjected to Shapiro-Wilk test to determine whether these data were fitted to a normal distribution. RESULTS The twenty volunteers can be classified into extensive metabolizers and poor metabolizers according to pharmacokinetic parameters. The main parameters in the two groups obtained were as follows: T1/2 were 21±4 and 38±9 h, AUC0-∞ were 49±10 and 110±8 μg*h*mL-1, respectively. Even the AUC data in extensive metabolizers were 1.7 times as that reported in White volunteers following the same doses of meloxicam. CONCLUSION　There were significant individual differences in the pharmacokinetics of meloxicam in Chinese volunteers, which may be due to the genetic polymorphism of CYP2C9.

To study the drug-drug interaction of morinidazole and warfarin and its application, a sensitive and rapid liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed for the determination of R-warfarin/S-warfarin in human plasma. In a random, two-period crossover study, 12 healthy volunteers received a single oral dose of 5 mg racemic warfarin in the absence and presence of morinidazole. Blood samples were collected according to a pre-designed time schedule. R-warfarin, S-warfarin and methyclothiazide were extracted with ethylether : methylenechloride (3 : 2), then separated on a Astec Chirobiotic V (150 mm x 4.6 mm ID, 5 microm) column using 5 mmol x L(-1) ammonium acetate (pH 4.0) - acetonitrile as mobile phase at a flow-rate of 1.5 mL x min(-1). The mobile phase was splitted and 0.5 mL x min(-1) was introduced into MS. A tandem mass spectrometer equipped with electrospray ionization source was used as detector and operated in the negative ion mode. Quantification was performed using multiple reaction monitoring (MRM). The resolution of warfarin enantiomers is 1.56. The linear calibration curves for R-warfarin and S-warfarin both were obtained in the concentration range of 5 - 1 000 ng x mL(-1). Intra- and inter-day relative standard deviation (RSD) for R-warfarin and S-warfarin over the entire concentration range across three validation runs was both less than 10%, and relative error (RE) ranged from -4.9% to 0.7%, separately. The method herein described is effective and convenient, and suitable for the study of metabolic interaction between morinidazole and warfarin. The results showed that coadministration of warfarin with morinidazole did not affect the pharmacokinetics of either R-warfarin or S-warfarin.

The study aims to evaluate the bioequivalence of valsartan hydrochlorothiazide tablets, and to investigate the potential cause of bioinequivalence. This was a single-center study with an open, randomized double-way crossover design. Test and reference preparations containing 160 mg of valsartan and 25 mg of hydrochlorothiazide were given to 36 healthy male volunteers. Plasma concentrations of valsartan and hydrochlorothiazide were determined simultaneously by LC-MS/MS. The pharmacokinetic parameters and relative bioavailability were calculated, while the bioequivalence between test and reference preparations were evaluated. The dissolution profiles of test and reference preparations in four different mediums were determined via dissolution test and HPLC. The similarity was investigated according to the similarity factors (f2). The F(o-t) and F(0-infinity) were (139.4 +/- 65.2)% and (137.5 +/- 61.2)% for valsartan of test preparations. It led to get the conclusion that test and reference preparations were not bioequivalent for valsartan. A significant difference was observed between test and reference tablets in the valsartan dissolution test of pH 1.2 hydrochloric acid solution. The key factor of the bioinequivalence might be that dissolution of valsartan in acid medium has marked difference between two preparations.

To study the metabolite excretion of theophylline, a rapid and specific method by liquid chromatography with heated electrospray ionization tandem mass spectrometry (LC-HESI/MS/MS) method for simultaneous determination of theophylline, 1, 3-dimethyluric acid (1,3-DMU), 3-methylxanthine (3-MX) and 1-methyluric acid (1-MU) in human urine was developed using theophylline-d6 and 5-fluorouracil as internal standards. Selected reaction monitoring (SRM) with heated electrospray ionization (HESI) was used in the negative mode for mass spectrometric detection. After diluted with methanol and centrifuged, the analytes and ISs were separated on a XDB-Phenyl (150 mm x 4.6 mm, 5 microm) column with a mixture of water-methanol-formic acid (30 : 70 : 0.15) as mobile phase at a flow rate of 0.6 mL x min(-1). The linear calibration curves for theophylline, 1, 3-DMU, 3-MX and 1-MU were obtained in the concentration range of 1.0-250 microg x mL(-1), separately. The method herein described is effective and convenient, and can be used for determination of theophylline and its three metabolites. The results showed that urinary excretion ratio of theophylline, 1,3-DMU, 3-MX and 1-MU is approximately 1 : 3 : 1 : 2 in Chinese subjects, which is similar to the reported excretion pattern in Caucasian.

A chiral LC-MS/MS method for the simultaneous analysis of desvenlafaxine (DVS) enantiomers in human plasma was developed and applied to a pharmacokinetic study on 12 Chinese healthy volunteers. d6-Desvenlafaxine was used as internal standard (IS). Chromatographic separation was performed on the Astec Chirobiotic V chiral column (150 mm x 4.6 mm, 5 μm). The assay was linear over the concentration range of 0.500-150 ng x mL(-1) for both enantiomers (r2 > 0.99). The method was successfully applied to a stereoselective pharmacokinetic study of 100 mg desvenlafaxine sustained release tablets on 12 Chinese healthy volunteers under fasting conditions. The results showed that the pharmacokinetic parameters were similar to both enantiomers in Chinese healthy volunteers. The AUC(0-t), and C(max) of the two enantiomers were about 1.5 times higher than those of blacks and whites reported in the literature.

A sensitive, rapid and accurate liquid chromatography-tandem mass spectrometric (LC-MS/MS) method with pre-column derivatization was developed for the simultaneous determination of erdosteine and its thiol-containing active metabolite in human plasma. Paracetamol and captopril were chosen as the internal standard of erdosteine and its active metabolite, respectively. Aliquots of 100 microL plasma sample were derivatized by 2-bromine-3'-methoxy acetophenone, then separated on an Agilent XDB-C18 (50 mm x 4.6 mm ID, 1.8 microm) column using 0.1% formic acid methanol--0.1% formic acid 5 mmol x L(-1) ammonium acetate as mobile phase, in a gradient mode. Detection of erdosteine and its active metabolite were achieved by ESI MS/MS in the positive ion mode. The linear calibration curves for erdosteine and its active metabolite were obtained in the concentration ranges of 5-3 000 ng x mL(-1) and 5-10 000 ng x mL(-1), respectively. The lower limit of quantification of erdosteine and its active metabolite were both 5.00 ng x mL(-1). The pharmacokinetic results of erdosteine and its thiol-containing active metabolite showed that the area under curve (AUC) of the thiol-containing active metabolite was 6.2 times of that of erdosteine after a single oral dose of 600 mg erdosteine tables in 32 healthy volunteers, The mean residence time (MRT) of the thiol-containing active metabolite was (7.51 +/- 0.788) h, which provided a pharmacokinetic basis for the rational dosage regimen.

Objective: To compare the value of MRI total burden and diffusion tensor tract-based spatial statistics (TBSS) for identifying cognitive impairment in patients with cerebral small vascular disease (CSVD). Methods: Consecutive patients with CSVD diagnosed in Suzhou Hospital Affiliated to Nanjing Medical University from January 2018 to June 2019 were enrolled. They were divided into cognitive impairment group and cognitive normal group. The MRI overall burden was evaluated, and TBSS analysis was performed to obtain regions with differences in diffusion parameters between the two groups. Multivariate logistic regression analysis was used to determine the independent risk factors for cognitive impairment. The receiver operating characteristic (ROC) curve was used to identify the recognition ability of the MRI overall burden and TBSS analysis for cognitive impairment in patients with CSVD. Results: A total of 71 patients with CSVD were enrolled, including 41 (57.75%) in the cognitive impairment group and 30 (42.25%) in the cognitive normal group. There was a statistically significant difference in the proportion of patients with white matter hyperintensities between the two groups, but the MRI overall burden was not statistically significant difference. After adjusting for the confounding factors such as age and gender, multivariate logistic regression analysis showed that white matter hyperintensities was an independent risk factor for cognitive impairment in patients with CSVD (odds ratio 3.459, 95% confidence interval 1.196-10.007; P=0.022). Diffuse parameters of the white matter area, such as the genu of corpus callosum, anterior thalamic radiation, fasciculus longitudinalis superior, and frontal-occipital fasciculus in the cognitive impairment group were significantly different from those in the cognitive normal group (all P<0.05). The fractional anisotropy of left anterior thalamic radiation (r=0.252, P=0.036) and the radial diffusivity of the genu of corpus callosum (r=-0.246, P=0.042) were significantly correlated with cognitive scores. ROC analysis showed that the areas under the curve of the MRI total burden, the fractional anisotropy of left anterior thalamic radiation, and the radial diffusivity of the genu of corpus callosum for identifying cognitive impairment were 0.61, 0.56 and 0.57, respectively. Conclusion White matter hyperintensities is an independent risk factor for cognitive impairment in patients with CSVD. TBSS analysis may be superior to MRI overall burden assessment in the specific recognition of cognitive impairment in patients with CSVD. Some diffuse parameters have a certain correlation with the overall cognitive status, and may be used as early imaging markers for cognitive impairment in patients with CSVD.

Objective To observe the effects of melatonin (MT) on the expression of heme oxygenase-1 (HO-1),phosphorylated adenine dinucleotide quinone oxidoreductase-1 (NQO-1) and nuclear factor erythroid-2-related factor 2 (Nrf2),so as to explore the mechanism of MT's action in the Nrf2-ARE signaling pathway.Methods A total of 72 Sprague-Dawley rats were randomly divided into a control group,an injury group and a melatonin group,each of 24.T11-T12 acute SCI was induced in the injury and melatonin groups using the modified Allen's method.Ten minutes after the injury,equal amounts of absolute ethyl alcohol and melatonin were intraperitoneally injected into the rats in the injury and melatonin groups.For the control group,the vertebral plate was cut to expose the T11-T12 spinal cord without any injury of the nerves.Six rats from each group were randomly selected for sacrifice at 6,12 and 24 hours after the operation,and T11-T12 spinal cord specimens were collected.The spinal cord injury and inflammatory response were observed using haematoxylin eosin staining.The expression of HO-1,NQO-1 and Nrf2 was examined using immunofluorescence,while the expression of HO-1,NQO-1 and Nrf2 protein and mRNA were detected using RT-PCRs.Results The neuronal cells in the spinal cords of the control rats were of normal shape,without edema,necrosis or obvious hemorrhagic foci.Hemorrhagic foci,significantly more inflammatory cells and some spinal cord neurons with edema and necrosis were observed in the injury group.However,significantly fewer hemorrhagic spots and cells with edema were found in the melatonin group compared with the injury group.The average expression of HO-1,NQO-1 and Nrf2 protein and mRNA was significantly higher in the melatonin group than in the other two groups.The levels in the injury group were also significantly higher than in the control group 12 and 24 hours after the experiments.Immunofluorescence showed that the greatest number of cells with HO-1,NQO-1 and Nrf2 was found in the melatonin group,followed by the injury group and then the control group,with significant differences among all 3 groups.Conclusion Melatonin can promote the expression of HO-1,NQO-1 and Nrf2 in rats with acute spinal cord injury,which might be related with its activating the Nrf2-ARE signaling pathway.

This study aims to develop a liquid chromatography with tandem mass spectrometry (LC-MS/MS) method for the simultaneous determination of ivabradine and N-demethylivabradine in human plasma, and investigate effects of stable isotope labeled (SIL) internal standard (IS) on ivabradine. The analytes and IS were extracted from plasma by protein precipitation with acetonitrile, and chromatographied on a Capcell PAK C18 (100 mm x 4.6 mm, 5 μm) column using a mobile phase of methanol and 5 mmol x L(-1) ammonium acetate. Multiple reaction monitoring with electrospray ionization (ESI) was used in the positive mode for mass spectrometric detection. The effect of ivabradine isotope peak [M+H+3] + on IS and the effect of SIL IS purity on ivabradine were evaluated. An appropriate concentration of SIL IS was chosen to permit method selectivity and linearity of the assay over the required range. The standard curves were demonstrated to be linear in the range of 0.100 to 60.0 ng x mL(-1) for ivabradine, and 0.050 0 to 20.0 ng x mL(-1) for N-demethylivabradine. The intra and inter day precision and accuracy were within the acceptable limits for all concentrations. Besides, the interaction between IS and ivabradine did not impact the determination of analytes. This method was successfully applied to a pharmacokinetic study of hydrogen sulfate ivabradine sustained release tablets on Chinese healthy volunteers.

Objective To investigate the expression of normal epithelial cell-specific-1(NES1) gene in normal gastric epithelial cells and different gastric cancer cell lines and the effects of 5-aza-2-de- oxycytidine(5-aza-dC)on the expression of NES1 gene.Methods Expression of NES1 mRNA in five gastric cancer cell lines(MKN-28,SGC-7901,AGS,MKN-45 and HGC-27)and normal human gastric epithelial cells were detected by real-time PCR.After treatment with 5-aza-dC,a DNA methyltransferase inhibitor,the expression of NES1 mRNA in gastric cancer cell lines was detected by real-time PCR. DNA methylation status of NES1 gene was assayed by methylation-specific PCR(MSP).Results The expression of NES1 mRNA was decreased in all gastric cancer cell lines.A strong correlation between ex on 3 hypermethylation and loss of NES1 mRNA expression in gastric cancer cell lines was noted.5-aza dC treatment of NES1-nonexpressing tumor cell lines resulted in a dose-dependent induction(SGC-7901, MKN-45,MKN-28 and AGS)and increase (HGC-27) of NES1mRNA expression in gastric cancer cells. Conclusions The study suggested that hypermethylation was a responsible factor for tumor-specific loss of NES1 gene expression in gastric cancer cells.Treatment of gastric cancer cell lines with a demethylating agent led to reexpression of NES1 suggesting an important role of hypermethylation in loss of NES1 gene expression.