Establishment of a system for finding inhibitors of ε RNA binding with the HBV polymerase.

Although several nucleo(s)tide analogs are available for treatment of HBV infection, long-term treatment with these drugs can lead to the emergence of drug-resistant viruses. Recent HIV-1 studies suggest that combination therapies using nucleo(s)tide reverse transcriptase inhibitors (NRTIs) and non-nucleo(s)tide reverse transcriptase inhibitors (NNRTIs) could drastically inhibit the viral genome replication of NRTI-resistant viruses. In order to carry out such combinational therapy against HBV, several new NRTIs and NNRTIs should be developed. Here, we aimed to identify novel NNRTIs targeting the HBV polymerase terminal protein (TP)-reverse transcriptase (RT) (TP-RT) domain, which is a critical domain for HBV replication. We expressed and purified the HBV TP-RT with high purity using an Escherichia coli expression system and established an in vitro ε RNA-binding assay system. Then, we used TP-RT in cell-free assays to screen candidate inhibitors from a chemical compound library, and identified two compounds, 6-hydroxy-DL-DOPA and N-oleoyldopamine, which inhibited the binding of ε RNA with the HBV polymerase. Furthermore, these drugs reduced HBV DNA levels in cell-based assays as well by inhibiting packaging of pregenome RNA into capsids. The novel screening system developed herein should open a new pathway the discovery of drugs targeting the HBV TP-RT domain to treat HBV infection.

PK/PD modeling based on NO-ET homeostasis for improving management of sunitinib-induced hypertension in rats.

Sunitinib is an oral small molecule multitargeted tyrosine kinase inhibitor, which is currently used to treat severe cancers. Clinical research has shown that patients treated with sunitinib develop hypertension. As soon as sunitinib-induced hypertension appears, it is usual to administer anti-hypertension agent. But this treatment may cause acute blood pressure fluctuation which may lead to additional cardiovascular risk. The aim of this study is to establish a mathematical model for managing sunitinib-induced hypertension and blood pressure fluctuation. A mechanism-based PK/PD model was developed based on animal experiments. Then this model was used to perform simulations, thus to propose an anti-hypertension indication, according to which the anti-hypertension treatment might yield relative low-level AUC and fluctuation of blood pressure. The simulation results suggest that the anti-hypertension agent may yield low-level AUC and fluctuation of blood pressure when relative ET-1 level ranges from -15% to 5% and relative NO level is more than 10% compared to control group. Finally, animal experiments were conducted to verify the simulation results. Macitentan (30 mg/kg) was administered based on the above anti-hypertension indication. Compared with the untreated group, the optimized treatment significantly reduced the AUC of blood pressure; meanwhile the fluctuation of blood pressure in optimized treatment group was 70% less than that in immediate treatment group. This work provides a novel model with potential translational value for managing sunitinib-induced hypertension.

A mini-network balance model for evaluating the progression of cardiovascular complications in Goto-Kakizaki rats.

Cardiovascular complications represent a leading cause of mortality in patients with type 2 diabetes mellitus (T2DM). During such complicated progression, subtle variations in the cardiovascular risk (CVR)-related biomarkers have been used to identify cardiovascular disease at the incipient stage. In this study we attempt to integrally characterize the progression of cardiovascular complications and to assess the beneficial effects of metformin combined with salvianolic acid A (Sal A), in Goto-Kakizaki (GK) rats with spontaneous T2DM. The rats were treated with metformin (200 mg·kg-1·d-1, ig) alone or in combination with Sal A (1 mg·kg-1·d-1, ip) at ages from 8 to 22 weeks. During the treatment, the levels of asymmetric dimethylarginine, L-arginine, superoxide dismutase, malondialdehyde, glucose, high density lipoprotein and low density lipoprotein were assessed. Based on alterations in these biomarkers, a mini-network balance model was established using matrixes and vectors. Radar charts were created to visually depict the disruption of CVR-related modules (endothelial function, oxidative stress, glycation and lipid profiles). The description for the progression of cardiovascular disorder was quantitatively represented by u, the dynamic parameter of the model. The modeling results suggested that untreated GK rats tended to have more severe cardiovascular complications than the treatment groups. Metformin monotherapy retarded disease deterioration, whereas the combination treatment ameliorated the disease progression via restoring the balance. The current study, which focused on the balance of the mini-network and interactions among CVR-related modules, proposes a novel method for evaluating the progression of cardiovascular complications in T2DM as well as a more beneficial intervention strategy.

Detection of the Adulteration of Dendrobium Huoshanense with Dendrobium Henanense by UV-Vis-Shortwave Near-Infrared Diffuse Reflectance Spectroscopy Combined with Chemometrics.

BACKGROUND: Dendrobium huoshanense (DHS) is a classic traditional Chinese medicine (TCM) with distinctive medicinal benefits and great economic worth; nevertheless, because of similar tastes and looks, it is simple to adulterate with less expensive substitutes (such as Dendrobium henanense [DHN]). OBJECTIVE: This work aimed to develop a reliable tool to detect and quantify the adulteration of DHS with DHN by using UV-Vis-shortwave near-infrared diffuse reflectance spectroscopy (UV-Vis-SWNIR DRS) combined with chemometrics. METHODS: Adulterated samples prepared in varying concentrations (0-100%, w/w) were analyzed with UV-Vis-SWNIR DRS methods. Partial least-square-discriminant analysis (PLS-DA) and partial least-squares (PLS) regression techniques were used for the differentiation of adulterated DHN from pure DHS and the prediction of adulteration levels. RESULTS: The PLS-DA classification models successfully differentiated adulterated and nonadulterated DHS with an over 100% correct classification rate. UV-Vis-SWNIR DRS data were also successfully used to predict adulteration levels with a high coefficient of determination for calibration (0.9924) and prediction (0.9906) models and low error values for calibration (3.863%) and prediction (5.067%). CONCLUSION: UV-Vis-SWNIR DRS, as a fast and environmentally friendly tool, has great potential for both the identification and quantification of adulteration practices involving herbal medicines and foods. HIGHLIGHTS: UV-Vis-SWNIR DRS combined with chemometrics can be applied to identify and quantify the adulteration of herbal medicines and foods.

Establishment of a forward primers-superposed amplification analysis for accurate aspirin pharmacogenomic measurement.

Genotyping of gDNA rs12041331 (PEAR1), rs6065 (GP1BA), and rs730012 (LTC4S) can provide systematic guidance on the use of aspirin. However, an accurate, reliable and economical approach to simultaneous detection of the above single nucleotide polymorphisms (SNPs) is not reported. Herein, we designed and substantiated an allele-specific (AS) forward primer-superposed amplification analysis for measurement of the SNPs in PEAR1, GP1BA and LTC4S genes, in which the values of ∆Cq (differences in threshold cycles between the wild-type forward primer-based assay and the mutated-type forward primer-based assay) were employed to decide genotype. Mismatch AS forward primers were screened with the singleplex amplification analysis. Moreover, Cq extension optimized by AS forward primer superposition was observed in the selected forward primer-based triplex analysis. Further, robustness assessment of the triplex analysis showed the amplification efficiency ranging from 0.9 to 1.1. Precision test demonstrated the coefficient of variation of less than 2%. And the detective results of 189 DNA samples was completely concordant with that of commercial Sanger sequencing. In summary, we developed a simple, accurate and economical approach to genotyping of rs12041331 (PEAR1), rs6065 (GP1BA) and rs730012 (LTC4S) to provide a valuable pharmacogenomics tool for guidance of aspirin delivery.

[Relationship between morphology and pathogenicity of Blastocystis hominis trophozoites].

Six hundred and eighty-six fresh fecal specimens were collected from outpatients (663 well-formed feces and 23 watery feces) during March 2011 to March 2012. All specimens were examined microscopically by direct smear and iodine stained method. B. hominis obtained from the human positive fecal specimens were cultured in LES medium, and inoculated into the abdominal cavity of 10 female mice of 6-8-week old. The abdominal fluid was examined with same methods. 103 of 686 patients were positive (80 well-formed feces and 23 watery feces). Micro-scopically, the granular form and vacuolated form of B. hominis trophozoites could be easily identified by direct smear and iodine staining in well-formed fecal specimens, showing ovoid in shape and about (13.2 +/- 0.2) microm in size. The trophozoites cultured in LES medium showed similar feature. But in the watery fecal specimens and mice ascites specimen, they were amorphous containing more granules. And their average size was (28.0 +/- 0.3) microm which was larger than the former. Moreover, the ameba form of B. hominis trophozoites was also detected in the 23 watery fecal specimen and mice ascites specimen. The trophozoites of B. hominis were varying in shape and size depending on their living environment.

[Investigation on the infection of Blastocystis hominis in populations in Bama Yao Autonomous County of Guangxi].

497 fecal specimens were collected from 5 randomly selected villages of Bama County in December 2011, and tested for Blastocystis hominis infection using improved centrifugal sedimentation with hydrochloric acid-ether. Data were analyzed by villages, gender, occupation, age groups and ethnic populations. The results showed that 215 people of 497 were positive, with a prevalence of 43.3% (215/497). Pandang village had the highest infection rate of 55.7% (68/122), significantly higher than the other villages (P<0.05). There was no significant difference in genders, occupations, age groups and ethnic populations (P>0.05).

Simultaneous determination of phenols in the four main original plants of the famous traditional Chinese medicine Shihu by pressurized capillary electrochromatography.

A rapid pressurized capillary electrochromatography (pCEC) method has been established for the simultaneous analysis of 11 phenols in the four main original plants of the famous traditional Chinese medicine (TCM) Shihu. The effects of wavelength, mobile phase, flow rate, pH value, concentration of buffer, and applied voltage were systematically studied. The investigated 11 phenols could be isolated in 35 min on a reversed-phase EP-100-20/45-3-C18 capillary column using the established method. To apply the established pCEC method, all phenols except tristin (11) were detected in the four Dendrobium plants. A total of 10 components were detected in D. huoshanense, 6 components in D. nobile, 3 components in D. chrysotoxum, and 4 components in D. fimbriatum. The consistent evaluation revealed that the similarities among the four original plants of Shihu were 38.2-86.0% based on the 11 polyphenols and 92.5-97.7% based on the pCEC fingerprints. These further suggested that the components of the four original plants of TCM Shihu might be significantly different. Further investigation should be conducted to confirm and evaluate if the four species could be used as the same medicine with the same amount according to Chinese Pharmacopoeia (ChP).

Rapid Detection of Adulteration in Dendrobium Huoshanense with Dendrobium Henanense by ATR-FTIR Combined with Multivariate Methods.

Dendrobium huoshanense (DHS) has long been used to make tea drink, soup, and porridge to protect eye and liver in many Southeast Asian countries for centuries. As a rare and endangered functional food, adulteration in DHS with visually similar but cheaper and more accessible plants such as Dendrobium henanense (DHN) because of their similarities in morphology has become prevalent in the market. In this study, the Attenuated Total Reflectance Fourier transform Infrared Spectroscopy (ATR-FTIR) combined with chemometric methods was established to detect fraudulent addition in DHS with DHN. The partial least squares (PLS) models based on the ATR-FTIR files of DHS mixed with different proportions of DHN were built under cross validation and tested with different independent data sets. To reduce the variables' lack of information and increase the accuracy of the model, different wavelength selection methods including Moving Window Partial Least Squares (MW-PLS), Monte Carlo-uninformative variable elimination (MC-UVE), and interval random frog (iRF) were compared.The results showed that iRF performed the most perfectly with the number of latent variables (nLVs = 7), the lowest Root Mean Square Error of Cross-Validation (RMSECV = 7.37), and the maximum determination coefficients (R2 = 0.9721). The excellent performance of the model was proved by the low RMSEP value of 6.44% and the high R2 value of 0.9556. The developed method could rapidly quantify the adulteration DHN in DHS, and our study might provide an efficient and great potential technique tool for the rapid, green, low-cost, and nondestructive identification and quantification for DHS adulterated with DHN.

Simultaneous determination of 16 important biologically active phytohormones in Dendrobium huoshanese by pressurized capillary electrochromatography.

A rapid pressurized capillary electrochromatography (pCEC) method has been successfully developed for the simultaneous determination of 16 phytohormones in Dendrobium huoshanense. Effects of wavelength, mobile phase, the flow rate, pH value, concentration of buffer and applied voltage were investigated, respectively. The results showed that the 16 phytohormones could be baseline-separated rapidly in less than 21 min on a reversed-phase EP-100-20/45-3-C18 capillary column (total length of 45 cm, effective length of 20 cm, diameter of 100 µm, ODS packing inside for 3 µm) with ACN/5.0 mM ammonium acetate (containing 0.05% formic acid, pH = 3) as the mobile phase using gradient elution mode as follows: 0.1-10.0 min 40%ACN,10-15.0 min 70%ACN, 15.0-20 min 80% ACN, 20-21.0 min 80% ACN at a flow rate of 0.12 mL/min, applied voltage of -5 kV and a UV detection wavelength of 210 nm. The method validation howed that the established method is precise and stability, and the RSDs of intra- and inter-day precision based retention time and peak area were all below 5%. Employed the established method, in our experimental conditions, total 6 endogenous hormones including IAA, IBA, NAA, GA, ABA, t-Z were detected in D. huoshense. However, a relative larger amount of exogenous hormone 2,4-D (25.3 ~ 4.2 µg/kg) and 6-BA (79.5 ~ 35.4 µg/kg) were detected in 1 ~ 4 year old cultivated D. huoshense, suggesting there were still a certain amount of exogenous hormone residue in tissue-cultured D. huoshanese though they had been transplanted to field cultivation from the test-tube plantlets for several years.

Simultaneous analysis of 20 free amino acids by a single marker combined with an HPLC fingerprint evaluation of Dendrobium huoshanense.

A phenylhexyl isothiocyanate (PITC) precolumn derivatization quantitative analysis of multicomponents by a single marker (QAMS) strategy for the simultaneous analysis of 20 free amino acids (FAA) in Dendrobium huoshanense is proposed. The method was validated by the linearity, limit of detection (LDO), and limit of quantitation (LOQ), recovery, precision, and stability. The results showed that when applying the established method, the LOQ of the FFAs was lower than 1 ng/ml except threonine (1.32 ng) and cysteine (1.16 ng). The QAMS investigation revealed that, using any one of the 20 FAAs as the reference internal standard, no significant differences were observed between the external standard method and the QAMS method for the quantification of FAAs in D. huoshanense by PITC precolumn derivatization [The relative standard deviation (RSD, %) by QAMS and ESM were all below 5%]. HPLC fingerprint investigation combined with similar analysis (the similarity values for S1-S25 were >0.875) and quality fluctuation analysis showed that the cultivation environment might have a great effect on the accumulation of FAAs in D. huoshanense. Overall, our study showed that we might increase the accuracy and scope of the simultaneous quantification of multicomponents using the QAMS technique by being derivatized with a strong UV absorbing group, and QAMS combined with chromatographic fingerprinting can be considered good quality criteria for the quality control of D. huoshanense and may provide analytical technical support for research on Maillard Reaction during the further processing of D. huoshanense.

Simultaneous Quantification of 11 Phenolic Compounds and Consistency Evaluation in Four Dendrobium Species Used as Ingredients of the Traditional Chinese Medicine Shihu.

The interchangeable use of different herbs to prepare the same formulation is a common practice in Traditional Chinese Medicine (TCM). However, this practice would require the component herbs to share similar compositions, at least in terms of the bioactive agents, to ensure they can replace each other in drug preparation. In this study, we developed an effective and comprehensive high-performance liquid chromatography-diode array detector (HPLC-DAD) method for simultaneous analysis of 11 phenolic compounds in the methanol extracts of Dendrobium huoshanense, Dendrobium nobile (D. nobile), Dendrobium chrysotoxum (D. chrysotoxum), and Dendrobium fimbriatum (D. fimbriatum), which have been identified as interchangeable ingredients for the same TCM preparation "Shihu" in the Chinese pharmacopeia (ChP). The consistency of the four Dendrobium species was evaluated on the basis of the presence of the 11 investigated compounds and the HPLC fingerprints of the methanol extracts of the plants. When gradient elution was performed with a solvent system of acetonitrile and water on a Zorbax Eclipse XDB-C18 (150 mm × 4.6 mm, 5 µm) with monitoring at 220 nm, all 11 investigated compounds were isolated at the baseline. The established HPLC method showed excellent linearity (all analytical curves showed relative coefficients [R2] > 0.999), sensitivity, precision (relative standard deviation [RSD] < 2%), and accuracy (recovery, 90.65-99.17%). These findings confirmed that the method we constructed was reliable. Quantification analysis showed significant differences in the contents of the investigated polyphenols in the four Dendrobium species. Evaluations of consistency revealed that the similarities among the four species were 0.299-0.906 in assessments based on the 11 polyphenols and 0.685-0.968 in assessments based on HPLC fingerprints. Thus, the components of the four Dendrobium species may be significantly different, and more experiments are required to determine whether they can be used interchangeably in the same amounts for preparing the formulation according to ChP.

Pharmacokinetic interactions induced by content variation of major water-soluble components of Danshen preparation in rats.

AIM: To investigate the pharmacokinetic interactions induced by content variation of the main water-soluble components of Danshen injection in rats. METHODS: Intravenous Danshen injection (control) or Danshen injection with danshensu (DSS), protocatechuic aldehyde (PAL), salvianolic acid A (Sal A) or salvianolic acid B (Sal B) were administered to female Sprague Dawley rats. Plasma concentrations of DSS, Sal A, PAL and its oxidative metabolite protocatechuic acid (PA) were analyzed simultaneously with LC-MS/MS; concentrations of Sal B were determined by the LC-MS method. Non-compartmental pharmacokinetic parameters were calculated and compared for identifying the pharmacokinetic interactions among these components. RESULTS: Compared with the control group, the DSS, Sal A, and Sal B groups had significant increases in AUC(0-infinity) in response to elevated concentrations of PAL (by 78.1%, 51.0%, and 82.9%, respectively), while the clearances (CL) were markedly reduced (by 42.5%, 32.9%, and 46.8%, respectively). Similarly, Sal A increased the AUC(0-infinity) of DSS and Sal B (26.7% and 82.4%, respectively) and substantially decreased their clearances (21.4% and 45.6%, respectively). In addition, the pharmacokinetics of DSS and Sal B were significantly affected by the content variation of the other major components; the AUC(0-infinity) increased by 45.1% and 52.1%, respectively, the CL dropped by 29.6% and 27.1%, respectively, and the T(1/2) was decreased by 22.0% and 19.6%, respectively. CONCLUSION: Complex, extensive pharmacokinetic interactions were observed among the major water-soluble constituents in the Danshen injection. The content variation of PAL had the most significant effect on the pharmacokinetic behaviors of other major constituents. Furthermore, the pharmacokinetics of DSS and Sal B were the most susceptible to the content change of other components.

A sensitive and practical LC-MS/MS method for the determination of mizoribine in human serum and its bioequivalence study on Chinese healthy volunteers.

A high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) method was developed and validated for the determination of mizoribine in human serum using thiamphenicol as internal standard (IS). The serum samples of mizoribine were precipitated with acetonitrile and separated by HPLC on a reversed phase C18 column with a mobile phase of 0.1% ammonium acetate water solution-methanol (47:53, v/v). Mizoribine and IS were detected in the multiple reaction monitoring mode with precursor/product ion transitions of m/z 258.2/126.0 and 354.1/185.2, respectively. The calibration curves were linear over the range of 0.02-2 microg mL(-1) for mizoribine. The limit of quantification (LOQ) was 0.02 microg mL(-1) with acceptable precision and accuracy. The validated method was successfully applied for the evaluation of a bioequivalence study on Chinese healthy volunteers. The main pharmacokinetics parameters after oral administration of 100 mg mizoribine test or reference formulation were as follows: Cmax (1.00 +/- 0.21), (1.00 +/- 0.22) microg mL(-1); AUC(0-infinity) (6.72 +/- 1.39), (6.48 +/- 1.44) microg h mL(-1); t1/2 (2.77 +/- 0.26), (2.66 +/- 0.29) h; tmax (2.95 +/- 0.78), (2.84 +/- 0.50) h.

Stereoselective analysis of tiopronin enantiomers in rat plasma using high-performance liquid chromatography-electrospray ionization mass spectrometry after chiral derivatization.

A specific and relatively sensitive high-performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESI-MS) was developed for the quantitative analysis of tiopronin enantiomers in rat plasma. The method is based on the derivatization of (+)-tiopronin and (-)-tiopronin with 2,3,4,6-tetra-O-acetyl-beta-glucopyranosyl isothiocyanate (GITC) in acetonitrile. The separation of resulting diastereomic derivatives was performed on C18 column (150 mm x 2.0 mm ID, packed with 5.0 mum C(18) silica RP particle), using a mobile phase of methanol/water (containing 5.3 mM formic acid) with gradient elution. LC-MS was performed in the selected ion monitoring and positive ion mode using target ions at m/z: 575 for the diastereomic derivatives of tiopronin and m/z: 603 for the derivative of N-isobutyryl-D-cysteine (internal standard). The method was validated in terms of specificity, linearity, sensitivity, precision, accuracy, matrix effect, and stability. The calibration curves were linear over the concentration range of 0.025-5 microg/ml for both enantiomers of tiopronin. For both enantiomers of tiopronin, the interbatch and intrabatch variability values were less than 15%, and the accuracy was within +/-17% in terms of relative error. The method was successfully applied to a pharmacokinetic study of rac-tiopronin in rat.

[Cloning, expression and identification of surface antigen SAG4 of Toxoplasma gondii].

OBJECTIVE: To clone and express surface antigen SAG4 gene of Toxoplasma gondii, and analyze its immunoreactivity. METHODS: Specific primers were designed based on the reported SAG4 gene of T. gondii RH strain (GenBank Accession No: AF340224.1). Using genomic DNA from T. gondii as templates, SAG4 gene was amplified by PCR. The PCR product was cloned into pMD19-T vector and identified by digestion with restriction enzyme and PCR. Then the target fragment was subcloned into pET28a(+) vector, transformed into E. coli BL21 and followed by expression of the protein induced by IPTG. The protein was identified by Western blotting. RESULTS: The target gene was amplified with the length of 537 bp. Sequence analysis showed that the predicted amino acid sequence was identical with that of SAG4 as a membrane protein in T. gondii. After induced by IPTG, the recombinant SAG4 protein existed in an inclusion body form. The recombinant SAG4 (Mr 18 740) was recognized by serum of infected mice. CONCLUSION: SAG4 has been expressed and shows certain immuno-response activity.

A method for quantifying the unstable and highly polar drug nafamostat mesilate in human plasma with optimized solid-phase extraction and ESI-MS detection: more accurate evaluation for pharmacokinetic study.

An advanced quantification method was developed with solid-phase extraction (SPE) and mass spectrometry (MS) determination for nafamostat, an unstable and highly polar drug, in human plasma. For unstable drugs with an ester group, the main analytical challenge is how to avoid the ester hydrolysis, and strong acid or alkaline conditions should be excluded during sample preparation. Considering that, we developed a relatively mild method with SPE for sample preparation without strong acid and alkaline treatment, which was optimized with different pHs and salt concentrations in phosphate-buffered saline treatment. The results indicated that pH 5 gave the most efficient extraction and 0.1 M salt concentration enhanced the extraction the most, with a minor effect on MS monitoring. The extraction method effectively avoided drug hydrolysis and achieved good drug enrichment over 82.2%. The linear range of quantification was 1.25-160 ng mL(-1). The stability of the drug in sample treatment was fully validated according to the sample processing procedure, including the stability in fresh blood, mobile phase, plasma and acidic methanol, and the results indicated that the drug remained stable during the whole sample preparation. Compared with a previous isotope-labeling method, more accurate and specific quantification of plasma concentration was achieved with liquid chromatography-electrospray ionization MS determination. With use of our method, nafamostat mesilate pharmacokinetics in 30 Chinese healthy volunteers was investigated with three doses via intravenous-drip infusion. The pharmacokinetic parameters were also estimated and compared with those of Japanese volunteers (slightly lower plasma concentration and longer terminal elimination half-life for Chinese volunteers). The difference in the pharmacokinetics may be ascribed to the quantification method, because previous isotope labeling may have overestimated the parent drug.

[Effect of phospholipid on absorption of diammonium glycyrrhizinate].

To investigate the absorption mechanism of diammonium glycyrrhizinate (GL) for oral use in rat intestine as well as the effect of phospholipids on GL and its metabolite glycyrrhetic acid (GA), in situ single pass intestinal perfusion model and the rat single-pass intestinal perfusion with mesenteric cannulation model were used and the concentrations of GL and GA in perfusate and blood were determined by HPLC. The apparent permeability values (Papp) of GA with or without phospholipids are 7.98 and 5.73 cm x min(-1), respectively, whereas the permeability of GL had no significant statistical difference. The results showed that phospholipids can increase the absorption extent and speed of GA. This action can be used in the research and development of the new drugs of the glycyrrhiza.

Warfarin maintenance dose adjustment with indirect pharmacodynamic model in rats.

The purpose of the study was to adjust the individual maintenance dose of warfarin with a simple approach based on indirect pharmacodynamic model (IDR). Based on the distinct pharmacokinetic and pharmacodynamic features of warfarin, the relationship between the maintenance dose and the steady-state anticoagulation effect was simplified and an approach for the maintenance dose adjustment was proposed. According to the steady-state anticoagulation effect before and after multiple doses (0.1 mg kg(-1)day(-1)), the optimal maintenance doses were predicted for the target anticoagulation effect (INR(target)=2.5), then the actual anticoagulation effect (prothrombin times, PT) on the 6th (8 pm)\8th (8 am)\10th (2 pm) day after dose adjustment according the present method was compared with the target effects with a view of determination the feasibility and accuracy of the proposed approach. The proposed method was also used to adjust warfarin maintenance doses in the presence of metabolism inhibitor metronidazole. The results suggested that the proposed approach could appropriately achieve the target international normalized ratio (INR(target)) when warfarin used alone or in combination with metronidazole, the actual INR values of three days were 2.69+/-0.18 and 2.52+/-0.22 (mean+/-S.D.), respectively. The method provided a relatively simple and accurate strategy for warfarin maintenance dose adjustment.

Pharmacokinetics, tissue distribution and excretion of gambogic acid in rats.

The plasma pharmacokinetics, excretion, and tissue distribution of gambogic acid (GA), a novel anti-tumor drug, were investigated after intravenous (i.v.) bolus administration in rats. Plasma profiles were obtained after i.v. administration of GA at the doses of 1, 2 and 4 mg/kg. The elimination half-life (tl/2) values for GA were estimated to be 14.9, 15.7 and 16.1 min, while the mean area under concentration-time curve (AUC(t)) values were 54.2, 96.1 and 182.4 microg min/ml, respectively. GA was mainly excreted into the bile (36.5% over 16 h). The cumulative sum of fecal excretion within 48 h was 1.26% of the i.v. administered dose. No GA was detected in the urine after i.v. administration. GA had a limited tissue distribution, with the highest concentrations being found in the liver. GA reached its maximal concentration in all tissues at 5 min post-dose. In conclusion, the present observations indicated that GA was rapidly eliminated from the blood and transferred to the tissues. Moreover, the majority of GA appeared to be excreted into the bile within 16 h of i.v. administration.