Aim To establish the pharmacokinetic principles of the zero-order release and the first-order release of mono-compartment drugs administered by non-parenteral route based on the release kinetics of the dosage forms and the intrinsic pharmacokinetic parameters of the active drug, such as the rate constants of the absorption and elimination, and the distribution volume of the drug. Methods By the Laplace transform and the compartmental analysis method, the pharmacokinetic behaviors of the zero-order release and the first-order release of mono-compartment drugs administered by non-parenteral routes were deduced with divisions of the dose being absorbed during the release phase and after the release has terminated. Results The pharmacokinetics of the non-parenteral administration of the zero-order release and the first-order release of mono-compartment drugs were established. Conclusion The pharmacokinetic theories of the zero-order release and the first-order release of mono-compartment drugs administered by non-parenteral route have been established. Since the zero-order release and the first-order release are the primary release patterns, the theory should be a key to explore the pharmacokinetics of the controlled/sustained release dosage forms.

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.

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.

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 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.

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.

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.

Aim To study the effects of Shenfu soup onthe ISO -induced myocardial ischemia injury model ofrats and the influence of apelin level changes on myocardial ischemia.Methods The myocardial ischemiainjury model of rats was established by the subcutaneous injection of ISO.For 1 5 days,rats in Shenfugroups were given by gavage 3,6 and 1 2 g · kg -1Shenfu soup and rats in SF injection group were given6.67 g·kg -1 Shenfu injection,rats in sham group andmodel group were given the same volume of distilledwater.Rats were subcutaneously multipoint injectedISO for 5 days on the eleventh administrating day.Theeffects of Shenfu soup on myocardial morphology,serum myocardial enzyme levels,apelin mRNA level inserum and apelin protein level in myocardial tissue,and relationship between myocardial enzyme and apelinexpression were evaluated. Results Shenfu soupcould reduce the degree of myocardial tissue necrosisand compared with model group,CK values and LDHvalues of rats in middleand highdose groups were significantly lower (P <0.05 or P <0.01 ).However,the apelin mRNA level in myocardial tissue and apelinprotein level in serum of the rats in middleand highdose groups compared with model group had increased(P <0.05,P <0.01 ).Meanwhile,serum levels ofapelin and the expression of myocardial enzyme CK andLDH were negatively correlated.Conclusion Shenfusoup has a protective effect on myocardial ischemia injury in rats induced by ISO and the mechanism is involved with the promotion of apelin mRNA and proteinexpression,the inhibition of myocardial enzyme production and the improvement of myocardial ischemia.

Objective: This study aimed to investigate the inhibitory effects of Brucea javanica oil oral emulsion (BJOOE) on primary liver cancer induced by diethylnitrosamine (DEN). Methods:Rats were randomly divided into the control group, model group, and BJOOE group. Rats were given free access to water. DEN was administered intragastrically to induce liver cancer in rats. Five weeks later, rats were intragastrically administered with BJOOE for five times per week. The rats were killed after 14 weeks. Abdominal aortic blood samples were collected. The contents of ALT, AST, ALP, γ-GT, and AFP of serum were detected by an automatic biochemical analyzer. The liver index, spleen index, thymus index, and changes in liver cancer nodules of the surface were observed in rats. Changes in the number of liver cancer nodules of the surface were detected by imaging. Results:Compared with the control group, the liver index, spleen index, and number of nodules of the model group significantly increased, whereas the thymus index significantly decreased (P<0.01). The levels of ALT, AFP, AST, ALP, andγ-GT of serum in the model group were significantly higher than those in the control group (P<0.01). Compared with the model group, BJOOE significantly reduced the liver index, spleen index, and number of cancer nodules, but increased the thymus index in the liver of rats with cancer (P<0.01). The levels of ALT, AFP, AST, ALP, andγ-GT of serum in rats with hepatic carcinoma significantly improved (P<0.01 or P<0.05). Conclusion:BJOOE could inhibit primary liver cancer, and the underlying mechanisms are complex.