High Resolution Determination of Ondansetron in Human Plasma by HPLC and Pharmacokinetics of Orally Disintegrating Tablets

Ahn To develop a high resolution HPLC method for the determination of ondansetron in human plasma and to study the pharmacokinetics of ondansetron in orally disintegrating tablets. Methods HPLC determination involved liquid-liquid extraction, separation on a CN column and ultraviolet detection at 310 ran with granisetron as an internal standard. Pharmacokinetics and bioequivalence of ondansetron in orally disintegrating tablets by direct compression and conventional 8 mg tablets were evaluated and compared in 20 healthy human male volunteers after a single oral dose in a randomized cross-over study. Results The limit of quantification was 0.25 ng· mL^-1. The recovery was about 85 % or over for ondan setron and about 90% for internal standard. Linearity was good within the concentration range of 0.5 - 50 ng·mL^-1 with r^2 ranging from 0.997 1 to 0.999 9. Intra- and inter-assay coefficients of variation ranged from 1.78% to 2.38% and 3.88% -5.19%, respectively. Accuracies for spiked concentrations of 2.0, 10.0, and 30.0 ng·mL^-1 were 104.7% ±4.4%, 102.2% ± 1.1%, and99.51% ±2.34%, respectively. Pharmacokinetic parameters of AUCo-t, AUCo-∞ , Cmax, Tmax, and T1/2 were 230.2 ± 78.0 ng·h·L^-1 , 265.2± 101.5 ng·h·mL^-1, 35.67 ± 8.94 ng·mL^-l, 1.51 ±0.79 h, and 5.00± 1.41 h for orally disintegrating tablets, respectively. The analysis of variance did not show any significant difference between orally disintegrating tablets and conventional tablets, and 90% confidence intervals fell within the acceptable range for bioequivalence. Conclusion High resolution HPLC method has been set up and applied in pharmacokinetic evaluation of ondansetron in orally disintegrating tablets.

Stereoselective HPLC Assay of TJ0711 Enantiomers by Precolumn Derivatization with GITC Using UV Detection and Its Application in Pharmacokinetics in Rats

This investigation describes a new precise, sensitive and accurate stereoselective RP-HPLC method for determination of the enantiomers of a novel α- and β-receptor blocking agent, 1-[4-（2-methoxyethyl） phenoxy]-3-[[2-（2- methoxyphenoxy） ethyl]amino]-2-propanol （T J0711）, in rat plasma. GITC was used for precolunm derivatization of T J0711 enantiomers. Enantiomeric resolution was achieved on a Eurospher-100 C18 column （250 mm×4.6 mm ID, 5-μm particle size）, with UV detection at 255 nm, and the mobile phase consisted of acetonitrile and water （58：42, v/v） containing 0.02% glacial acetic acid （v/v）. Using the chromatographic conditions described, T J0711 enantiomers were well resolved with mean retention time of 10.2 and 11.5 min, respectively. Linear response （r〉0.999） was observed over the range of 0.125-12.5 μg/mL of TJ0711 hydrochloride enantiomers. The mean relative standard deviation （RSD%） of the results of within-day precision was ≤ 10%. The proposed method was found to be suitable and accurate for the quantitative determination of T J0711 enantiomers in rat plasma, and it can be used in pharmacokinetic studies.

A Sensitive HPLC-MS/MS Analysis of Dencichine in Rat Plasma and Its Application to Pharmacokinetics

In order to quantitate dencichine in biological samples, a selective and sensitive method for the determination of dencichine in rat plasma based on high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed and validated. (l)-2-amino-3-(carboxymethylthio)propionic acid was used as the internal standard (I.S.). After a protein precipitation extraction with acetonitrile, dencichine and the I.S. were chromatographed on an Xterra MS-C18 column. The mobile phase was consisted of 20mmol/L ammonium acetate solution-acetonitrile (35:65, V/V) at a flow rate of 0.2 mL/min. The detection was performed on a triple quadrupole mass via electrospray ionization (ESI) source in the positive mode. The intra- and inter-day precision (relative standard deviation, R.S.D.) values of dencichine were below 6.7%. The extraction recoveries were up 85%. The lower limit of quantification was 20 ng/ml, which was sensitive enough to detect the analyte. The HPLC-MS/MS method was successfully applied to the pharmacokinetic study after an intravenous administration of dencichine in Sprague-Dawley (SD) rat.

Determination of Plasma Concentration of Cinnamic Acid by High-Performance Liquid Chromatography and Its Pharmacokinetics in Rats after Oral Administration of Zi-Shen Pill

Aim To develop a simple and sensitive high-performance liquid chromatographicmethod for determination of plasma concentration of cinnamic acid and pharmacokinetic study in ratsafter a single oral dose of traditional Chinese medicinal preparation Zi-Shen pill. Method Plasmasamples were acidified with hydrochloric acid and extracted with ethyl acetate . Cinnamic acid wasdetermined by HPLC using a G_(18) column. A mobile phase ofmethanbl-acetonitrile-water-triethyl-amine (7:22:73 = 0.2, V/V), with the pH adjusted to 4.0 withphosphoric acid, and with a UV detector set at 340 nm. Results The standard curve was linear overthe range of 1.92- 192.0 μg·mL^(-1). The LLOQ was 1.92 μg·mL^(-1) . The RSDs of within-day andbetween-day precision were < 8%. The mean recovery was 82.0% . Conclusion After validation, themethpd has been used to investigate the pharmacokinetic profiles of the traditional Chinesemedicinal preparation Zi-Shen pill.

Determination of Loratadine in Human Plasma by High Performance Liquid Chromatography-Electrospray Mass Spectrometry and Studies on Its Pharmacokinetics and Relative Bioavailability

A new HPLC MS method to determine loratadine in human plasma was established. The method involved extracting drug with organic solvent under basic conditions. The samples were seperated by ODS column and determined by mass detector. The calibration curve of loratadine was linear within the range of 0.4～100 ng·mL -1 with r=0.9995 . The recovery of this method was within 95%～104%, within day and between day RSD were less than 12%. To study the pharmacokinetics and relative bioavailability of loratadine tablets, two formulations of loratadine tablets were given to 18 healthy male volunteers according to a randomized 2 way cross over design. The C max , AUC 0 t and T max values of the two formulations were 51.89±20.18 ng·mL -1 and 52.48±22.35 ng·mL -1 ; 140.75±88.42 ng·h·mL -1 and 147.24±92.33 ng·h·mL -1 ; 0.81±0.35 h and 0.81±0.27 h respectively. Results from statistic analysis showed that there were no significant difference between the C max , AUC 0-t and T max values of the two formulations. The relative bioavailability of tablets I with respect to tablets II was 97%±13% from the AUC 0 t measurement. Bioequivalance was observed between the two tablets.

Determination of 6258-70,a new semi-synthetic taxane,in rat plasma and tissues:Application to the pharmacokinetics and tissue distribution study

Cancer is the leading cause of death all over the world.Among the chemotherapy drugs,taxanes play an important role in cancer treatment.6258-70 is a new semi-synthetic taxane which has a broad spectrum of antitumor activity.A fast and reliable high performance liquid chromatography-tandem mass spectrometry（HPLC-MS/MS） method was developed for quantification of 6258-70 in rat plasma and tissues in this paper.After extraction by liquid-liquid extraction method with methyl tert-butyl ether,the samples were separated on a Kinetex C_（18） column（50 mm × 2.1 mm,2.6 μm,Phenomenex,USA） within3 min.The method was fully validated with the matrix effect between 87.7%and 99.5%and the recovery ranging from 80.3%to 90.1%.The intra- and inter-day precisions were less than 9.5%and the accuracy ranged from-3.8%to 6.5%.The reliable method was successfully applied to the pharmacokinetics and tissue distribution studies of 6258-70 after intravenous administration in rats.The pharmacokinetic results indicated that the pharmacokinetic behavior of 6258-70 in rats was in accordance with linear features within tested dosage of 1 to 4 mg/kg,and there was no significant difference between the two genders.The tissue distribution study showed that 6258-70 had an effective penetration,spread widely and rapidly and could cross blood-brain barrier.The results of pharmacokinetics and tissue distribution may provide a guide for future study.

Determination of Piperazine Ferulate in Human Plasma by HPLC and Its Pharmacokinetic Study

Aim To establish a sensitive HPLC method for determination of piperazine ferulate and to study its pharmacokinetics in healthy volunteers. Methods Piperazine ferulate was separated on a Shimadzu C_ 18 column with acetic acid (0.1%)-methanol (60 ∶ 40, V/V) as mobile phase after liquid-liquid extraction, and detection was performed at 310 nm. Piperazine ferulate pharmacokinetic parameters after a single oral dose of 200 mg of piperazine ferulate dispersible tablets in 20 healthy male volunteers were calculate...

Determination of fleroxacin in human plasma by HPLC with fluorescence detection and the pharmacokinetic study

Aim To develop a sensitive and accurate HPLC method for the determination of fleroxacin in human plasma, and study its pharmacokinetics in healthy subjects. Methods The analytes were isolated fi＇om plasma by simple protein precipitation with methanol, separated on a Diamonsil C18 column by isocratic elution with the mobile phase consisted of 1% triethylamine at pH 4.8 （adjusted with phosphoric acid） and acetonitrile （80/20, V/V） at a flow rate of 1.0 mL.min^-1 and analyzed by fluorescence detector with an excitation at 290 nm and emission 458 nm. The pharmacokinetic study of fleroxacin was performed according to a double period crossover design. Results The weighted （1/x） calibration curve was linear over the plasma concentration range of 0.025 - 8.00 μg.mL^-1 The inter- and intra-day precisions （RSD/%） were no more than 5.16%, and the method accuracies and extraction recoveries at three concentrations ranged firom 99.1% to 100.9%, and 86.7% to 92.0%, respectively. Following oral administration at a dose of 400 mg fleroxacin, the main pharmacokinetic parameters for test and reference capsules were Cmax5.08 ± 0.78 and 5.38 ± 1.40 μg.mL^-1, tmax 1.72 ±0.79 and 1.82 ± 0.78 h, t1/2 11.68 ± 1.27 and 11.38 ± 1.51 h^-1, AUC0-∞ 78.44 ± 11.44 and 76.53 ± 13.24 μg.mL^-1.h, respectively. Conclusion The method is sensitive and accurate, and suitable for human pharmacokinetic study of fleroxacin.

Determination of Naftopidil in Dog Plasma by High Performance Liquid Chromatography and Study on Its Pharmacokinetics

建立HPLC方法测定犬血浆中的萘哌地尔浓度，研究萘哌地尔胶囊在犬体内的药物动力学。单剂量给予5只健康犬萘哌地尔胶囊200mg,血浆样品碱化后，经乙醚提取以乙腈：磷酸盐缓冲液（0．05mol·L^-1的磷酸二氢钾溶液，以0．1mol·L^-1的NaOH调节pH至6．5）＝60：40（v/v)为流动相，由ODS C18分析柱分离测定，紫外230nm为检测波长，维拉帕米为内标。线性范围为10ng·L^-1;方法回收率为：100．23±3．00％；检测限：8ng·mL^-1;日间RSD≤5.56%,日内RSD≤3．30％。本法简便，回收率和灵敏度高，可用于萘哌地尔制剂的药动学研究。单剂量给予犬萘哌地尔胶囊200mg后血药浓度随时间变化规律符合一级吸收一室模型，T1／2Ke为3．19±1．27h,Tmax为1.15±0.59h,Cmax为697.48±94.22ng·mL^-1.

Applications of HPLC/MS in the analysis of traditional Chinese medicines

In China, traditional Chinese medicines （TCMs） have been used in clinical applications for thousands of years. The successful hyphenation of high-performance liquid chromatography （HPLC） and mass spectrometry （MS） has been applied widely in TCMs and biological samples analysis. Undoubtedly, HPLC/MS technique has facilitated the understanding of the treatment mechanism of TCMs. We reviewed more than 350 published papers within the last 5 years on HPLC/MS in the analysis of TCMs. The present review focused on the applications of HPLC/MS in the component analysis, metabolites analysis, and pharmacokinetics of TCMs etc. 50% of the literature is related to the component analysis of TCMs, which show that this field is the most popular type of research. In the metabolites analysis, HPLC coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry has been demonstrated to be the powerful tool for the characterization of structural features and fragmentation behavior patterns. This paper presented a brief overview of the applications of HPLC/MS in the analysis of TCMs. HPLC/MS in the fingerprint analysis is reviewed elsewhere.

Comparative pharmacokinetics of chlorogenic acid after oral administration in rats

The present study was aimed at the comparison of the pharmacokinetics of pure chlorogenic acid and extract of Solanum lyratum Thunb. The animals were allocated to two groups, and were administered chlorogenic acid or extract of S. lyratum Thunb. at a dose of 50.0 mg/kg orally. Blood samples were collected up to 8 h post-dosing. Plasma chlorogenic acid analyses were performed using an HPLC method with UV detector. The pharmacokinetic parameters were evaluated using non-compartmental assessment. Significant differences existed in the two groups for AUCo-t, AUCo-∞ and CLz/F. The reliable HPLC method was successfully applied to the determination of chlorogenic acid in rat plasma at dosting of 50.0 mg/kz.

Preparation of anti-resistant stealthy liposomes by incorporating vincristine with quinacrine and the pharmacokinetics in Sprague-Dawley rats

Aim The objectives of the present study were to prepare stealthy vincristine plus quinacrine liposomes and evaluate the pharmacokinetics in Sprague-Dawley rats. Methods Anti-resistant stealthy liposomes were prepared by incorporating vincristine with quinacrine together using the ammonium sulfate gradient loading procedure. For the pharmacokinetic study, Sprague-Dawley rats were divided into two groups： each rat in the Group Ⅰwas administered intravenously via tail vein as stealthy liposomal vincristine plus quinacrine, and the Group Ⅱ similarly given as a mixture solution of free vincristine plus free quinacrine. The concentrations of vincristine and quinacrine in plasma were measured by HPLC with diode array detection and fluorescence detection, respectively. Results The mean particle size of stealthy liposomes was 135.9 ±7.1 nm and the encapsulation efficiencies of stealthy liposomes were 〉 90% for vincristine, and 〉 85% for quinacrine, respectively. Administered as the stealthy vincristine plus quinacrine liposomes, the plasma exposures of both vincristine and quinacrine were significantly extended, and the mean concentrations of both vincristine and quinacrine were significantly higher compared to those given as the mixture solution of free vincristine plus free quinacrine. The Cmax, t1/2, AUC0-24 h values of vincristine for stealthy liposomal group were significantly increased, but the total clearance Cl values decreased, as compared to those of free drug group, respectively. Similarly, the Cmax, t1/2 and AUC0-24 h values of quinacrine for the stealthy liposomal group were significantly increased, but the total clearance C1 values decreased, as compared to those of free quinacrine. Conclusion The anti-resistant stealthy liposomes are successfully prepared by incorporating vincristine with quinacrine, and the liposomes extend significantly the duration in blood circulation and improve evidently the plasma concentrations of both vincristine and quinacrine.

Study on the Pharmacokinetics and Relative Bioavailability of Irbesartan Capsules in Healthy Volunteers

The pharmacokinetics and relative bioavailability were studied in 18 healthy volunteers. A single oral dose of 150 mg irbesartan capsule (test) or tablet (reference) was given to each volunteer according to a randomized 2 way crossover study. The concentrations in plasma were determined by HPLC UV method. The main parameters of irbesartan capsules were: C max : 1.502±0.295 μg/ml, t max : 1.44±0.34 h, t 1/2 : 20.21±14.71 h, AUC 0 t : 11.087±3.443 μg/ml -1 ·h. The relative bioavailability of capsule to tablet was (101.4±28.9) %. The results of statistical analysis showed that two formulations were bioequivalent.

Pharmacokinetic study of inosiplex tablets in healthy Chinese volunteers by hyphenated HPLC and tandem MS techniques

Inosiplex is a compound formulation composed of inosine and p-acetaminobenzoic acid （PABA） salt of N,N-dimethylamino-2-propanol （DIP）. This study was to investigate the clinical plasma pharmacokiuetic properties of DIP and PABA after single and multiple oral doses of inosiplex tablets in healthy Chinese volunteers. The established LC/MS/MS method for plasma DIP determination had a linear range of 0.02-10 pg/mL, and the HPLC method for plasma PABA determination had a linear range of 0.0540 pg/mL. Linear pharmacokinetic characteristics were found with single oral doses of 0.5, 1.0 and 2.0 g. No obvious accumulation effects were observed for DIP and PABA.

Separation and determination of acetyl-glutamine enantiomers by HPLC–MS and its application in pharmacokinetic study

A high-performance liquid chromatography coupled with mass spectrometry(HPLC–MS) method was established for the separation and determination of acetyl-glutamine enantiomers(acetylL-glutamine and acetylD-glutamine) simultaneously. Baseline separation was achieved on Chiralpak AD-H column(250 mm ×4.6 mm, 5 μm). n-Hexane(containing 0.1% acetic acid) and ethanol(75:25, v/v) were used as mobile phase at a flow rate of 0.6 m L/min. The detection was operated in the negative ion mode with an ESI source. [M-H]-m/z187.0540 for enantiomers and [M-H]-m/z 179.0240 for aspirin(IS) were selected as detecting ions. The linear range of the calibration curve for each enantiomer was 0.05–40 μg/m L. The precision of this method at concentrations of 0.5–20 μg/m L was within 7.23%, and the accuracy was 99.81%–107.81%. The precision at LOQ(0.05 μg/m L) was between 16.28% and 17.56%, which was poor than that at QC levels. The average extraction recovery was higher than 85% for both enantiomers at QC levels. The pharmacokinetics of enantiomers was found to be stereoselective. There was not chiral inversion in vivo or in vitro between enantiomers.

An HPLC-MS/MS method for the quantitative determination of platy-codin D in rat plasma and its application to the pharmacokinetics of Platycodi Radix extract

AIMS: To develop an HPLC-MS/MS method for the quantification of platycodin D(PD) in rat plasma, and to acquire the main pharmacokinetic parameters of PD after oral administration of pure PD or of Platycodi Radix extract(PRE) containing PD. METHOD: Plasma samples were pretreated with solid-phase extraction using an Oasis HLB SPE cartridge. Madecassoside was used as the internal standard(IS). Chromatographic separation was achieved on an ODS column(100 mm × 2.1 mm i.d., 3.5 μm) with a mobile phase consisting of acetonitrile/water(30 : 70, V/V) containing 0.1 mmol L 1ammonium acetate at a flow rate of 0.25 mL min 1. The detection was performed on a triple quadruple tandem mass spectrometer using an electrospray ionization(ESI) source with a chromatographic run time of 3.0 min. The detection was operated by multiple reaction monitoring(MRM) of the transitions of m/z 1 223.6→469.2 for PD and of m/z 973.6→469.2 for madecassoside(IS), respectively. RESULTS: The calibration curve was linear from 5 to 2 000 ng mL 1(r2>0.99) with a lower limit of quantification(LLOQ) of 5 ng mL 1. The intra- and inter-day precision(relative standard deviation, RSD) values were below 15% and the accuracy(relative error, RE) was from 15% to +15% at three quality control(QC) levels. Plasma concentrations of PD were determined for 24 h after i.v. administration of PD, and oral administration of PD and PRE, respectively. The absolute oral bioavailability of PD in rats was found to be(0.48 ± 0.19)% when administered PD, and to be(1.81 ± 0.89)% when administered PRE. CONCLUSION: The developed HPLC-MS/MS method was successfully applied to assess the pharmacokinetic parameters and oral bioavailability of PD in rats after administration of PD and Platycodi Radix extract.

Comparative pharmacokinetics of five saponins after intravenous administration of TSFS injection and TSFS injection plus TFFG in rats under different physiological states

Sanqi is a popular traditional Chinese medicine and commonly used for promoting blood circulation and removing blood stasis. Notoginsenoside R1, ginsenoside Rg1, Re, Rb1 and Rd are the major active constituents of Sanqi. The purpose of the study was to investigate the pharmacokinetic behavior of the five active constituents from total saponin from Sanqi when it was used in the blood stasis animals or in combination with Gegen. The concentrations of the five active constituents in rat plasma were determined by an ultra-HPLC-ESI-MS/MS method. The main pharmacokinetic parameters were calculated and statistically analyzed using the unpaired student＆#39;s t-test. It was found that the pharmacokinetic parameters of notoginsenoside R1, ginsenoside Rg1 and Rb1 represented a statistically significant difference （Po0.05） between the normal rats and the blood stasis rats after administration of total saponin from Sanqi （TSFS）. And there were statistically significant differences （Po0.05） in the pharmacokinetic parameters of all the five constituents between administration of TSFS alone and combined with total flavonoid from Gegen （TFFG） in blood stasis rats. It suggested that the pharmacokinetic behavior of the active constituents from TSFS could be changed when it was used in blood stasis animals or in combination with TFFG.

Determination of fenticonazole in human plasma by HPLC–MS/MS and its application to pharmacokinetic studies

Two simple and sensitive high performance liquid chromatography–tandem mass spectrometry(HPLC–MS/MS) methods were developed and validated for the determination of fenticonazole in human plasma after percutaneous and intravaginal administration. Mifepristone was used as an internal standard(IS), and simple protein precipitation by acetonitrile containing 2% acetic acid was utilized for extracting the analytes from the plasma samples. Chromatographic separation was performed on a Kinetex XB-C_(18) column. The quantitation was performed by a mass spectrometer equipped with an electrospray ionization source in multiple reactions monitoring(MRM) positive ion mode using precursor-to-product ion transitions of m/z 455.2–199.1 for fenticonazole and m/z 430.2–372.3 for mifepristone. The validated linear ranges of fenticonazole were 5–1000 pg/m L and 0.1–20 ng/m L in plasma for the methods A and B, respectively. For the two methods, the accuracy data ranged from 85% to 115%, the intra- and inter-batch precision data were less than 15%, the recovery data were more than 90%, and no matrix interference was observed. The methods A and B were successfully validated and applied to the pharmacokinetic studies of fenticonazole gel in Chinese healthy volunteers after percutaneous and intravaginal administration, respectively.

Study on the pharmacokinetics of tea polyphenols injection in rat plasma

Objective To study pharmacokinetics of the main active ingredients(-)Epigallocatechin-3-gallate(EGCG)and(-)Epicatechin-3-gallate(ECG)of tea polyphenols(TP)injection in rats.Methods EGCG and ECG in rat plasma were analyzed by reversed-phase HPLC,by which EGCG and ECG were eluted from a Kromasil C18 column with a linear gradient mobile phase consisting of CH3CN-0.1% citric acid at a gradient flow rate of 1.0-1.5 mL·min-1 and monitored at a wavelength of 280 nm.Fifteen rats were randomly divided into 3 groups of 5 animals receiving iv administration of TP injection,formulated with catechins-containing extract from green tea,at doses of 150,100 and 50 mg·kg-1,respectively.Blood samples were collected pre-dosing and 2,5,10,20,40,60,90,120,180,240,300 min postdosing.Aliquots of obtained plasma(200 μL)were cleaned up by liquid-liquid extraction with double volumes of EtoAc and were reconstituted with 100 μL of 10% CH3CN aqueous solution before injecting to chromatograph.Results The time course of EGCG and ECG concentrations in rat plasma decayed in a biexponential fashion.Their iv pharmacokinetics could be described by the two-compartment model and first-order kinetics with t1/2β 112.39-145.20 min and 46.63-61.48 min,Vd 6.28-7.96 L·kg-1 and 0.90-1.22 L·kg-1,CL 0.034-0.044 L·kg-1·min-1 and 0.010-0.015 L·kg-1·min-1 for EGCG and ECG,respectively.Conclusions The EGCG and ECG in plasma of rats administered i.v.TP injection pharmacokinetically behaved with linear kinetics over dose range studied.The two catechin derivatives undergo rapid elimination from rat body.As compared with ECG,EGCG eliminates at a relatively slow rate,and is distributed very widely with a Vd greatly exceeding the volume of total body water,suggesting that EGCG is likely to enter the tissue cells or strongly bind to some tissues to exert its potent antioxidant effects.The aforementioned characteristics of EGCG may be due to its high lipophilicity.

Comparative study on pharmacokinetics of Cephradine in diabetic and normal rats

Objective To study effects of diabetes mellitus(DM)on pharmacokinetics of cephradine(CED)by comparing the difference in pharmacokinetic behaviours of CED between diabetic and normal rats.Methods DM was induced in male rats by a single iv injection of alloxan 60 mg·kg-1;rats whose blood glucose was over 16 mmol·L-1 were taken as DM group.The rats were divided into DM group and normal control(CTL)group,which were subdivided into low dose(90 mg·kg-1)and high dose(180 mg·kg-1)subgroups.CED was administered by iv or po routes.Blood samples collected at different time post dosing were analyzed by RP-HPLC to yield CED plasma concentration time course.Chromatographic separation was achieved on a Kromasil C18 column(250×4.6 mm ID,5 μm);mobile phase,consisting of 0.025 mol·L-1 KH2PO4-MeOH-CH3CN(87;6∶7 v/v),was delivered at 1.0 mL·min-1;UV detector was set at 261 nm.The peak area ratio of CED to cephalexin(CEX)as internal standard vs concentraion of CED was used to construct calibration curve.50 μL aliquots of TCA-deproteined plasma samples were injected into chromatograph.Results The methodology validation including specificity,precision,accuracy,recovery,limit of quantitation,linearity,stability,etc.,showed that the HPLC assay developed by us completely met requirements of pharmacokinetic study Both DM and CTL groups showed the two-compartment model for iv dosing and extravascular one-compartment model for po dosing as well as first-order kinetics.However,in iv experiment,DM group,when compared with CTL group,presented a significantly shortened t1/2β and MRT as well as increased CL,reflected by t1/2 β 84-91 vs 116-120 min,MRT 61-70 vs 103-119 min;CL 23-25 vs 18-19 mL·min-1·kg-1(P<0.05);in po experiment,a markedly shorter t1/2 K and tmax as well as greater CL and Cmax in DM group than in CTL group were found;meanwhile,DM rats suffered from remarkably increased kidney weight(KW)and KW/BW ratio relative to CTL rats.Conclusions DM pathological status can speed up elimination of CED from body of rats;the compensatory hypertrophy and thereby hyperfunction of kidneys in early-stage diabetics may explain in part at least this accelerated elimanation.