Autonomous sensing of the insulin peptide by an olfactory G protein-coupled receptor modulates glucose metabolism.

Along with functionally intact insulin, diabetes-associated insulin peptides are secreted by ß cells. By screening the expression and functional characterization of olfactory receptors (ORs) in pancreatic islets, we identified Olfr109 as the receptor that detects insulin peptides. The engagement of one insulin peptide, insB:9-23, with Olfr109 diminished insulin secretion through Gi-cAMP signaling and promoted islet-resident macrophage proliferation through a ß cell-macrophage circuit and a ß-arrestin-1-mediated CCL2 pathway, as evidenced by ß-arrestin-1-/- mouse models. Systemic Olfr109 deficiency or deficiency induced by Pdx1-Cre+/-Olfr109fl/fl specifically alleviated intra-islet inflammatory responses and improved glucose homeostasis in Akita- and high-fat diet (HFD)-fed mice. We further determined the binding mode between insB:9-23 and Olfr109. A pepducin-based Olfr109 antagonist improved glucose homeostasis in diabetic and obese mouse models. Collectively, we found that pancreatic ß cells use Olfr109 to autonomously detect self-secreted insulin peptides, and this detection arrests insulin secretion and crosstalks with macrophages to increase intra-islet inflammation.

[Pharmacokinetics of Phosphate Retagliptin Tabletin in Patients with Renal Dysfunction].

OBJECTIVE: To compared the differences in pharmacokinetics of phosphate retagliptin tablets in patients with varying degrees of renal dysfunction. METHODS: A total of 32 patients were categorized into five groups according to their renal function: normal,mild dysfunction, moderate dysfunction,severe dysfunction,and end stage renal dysfunction (ESRD). All of the patients took a single dose of 50 mg phosphate retagliptin tablet. Their plasma and urinary concentrations of phosphate retagliptin (SP2086) and phosphate retagliptin acid (SP2086 acid) were determined using LC-MS/MS methods. The plasma pharmacokinetic parameters were calculated using WinNolin 6.1 software. RESULTS: Peak concentrations (Cmax) of SP2086 reached at (1.07±0.35) h in the patients with mild renal dysfunction,(1.50±0.89) h in the patients with moderate renal dysfunction,(1.67±2.16) h in the patients with severe renal dysfunction,(2.42±2.15) h in the patients with ESRD,and (1.75±1.21) h in the normal participants,with a clearance (CL/F) of (23.50±6.01) ,(12.90±4.34) ,(6.70±1.55) ,(3.10±0.48) ,and (30.50±10.70) L/h,respectively. With the increasing damages in renal function presented an incease in Cmax,time to reach Cmax (Tmax),and area under curve (AUC), a decrease in CL/F, of SP2086 and SP2086 acid. The 0-96 hurine cumulative excretion percentage (Ae%) of SP2086 ranged from 0.441% to 4.530%. The Ae% of SP2086 acid reached (71.7±14.3) % in the patients with mild renal dysfunction, (59.5±22.7) % in the patients with moderate renal dysfunction, (63.3±13.9) % in the patients with severe renal dysfunction, (34.1±20.0) % in the patient with ESRD,and (74.2±14.6) % in the normal participants, with a renal clearance (CL/R) of (220.0±51.2),(105.0±64.5),(54.5±7.6),(13.5±7.8),and (289.0±73.7) mL/min,respectively. Compared with the participants with normal renal function,the AUCs of SP2086 and SP2086 acid were 1.44 times and 2.32 times higher in the patients with moderate renal dysfunction,2.20 times and 4.39 times higher in the patients with severe renal dysfunction, and 2.83 times and 9.28 times higher in the patients with ESRD. CONCLUSION: The dosage of phosphate retagliptin tablet is recommended at 100 mg/d for patients with normal renal function and those with mild renal dysfunction,at 50 mg/d for patients with moderate renal dysfunction,and at 25 mg/d for patients with severe renal dysfunction. No phosphate retagliptin tablet is recommended for patients with ESRD.

The regioselective glucuronidation of morphine by dimerized human UGT2B7, 1A1, 1A9 and their allelic variants.

Uridine diphosphate-glucuronosyltransferase (UGT) 2B7 is expressed mostly in the human liver, lung and kidney and can transfer endogenous glucuronide group into its substrate and impact the pharmacological effects of several drugs such as estriol, AZT and morphine. UGT2B7 and its allelic variants can dimerize with the homologous enzymes UGT1A1 and UGT1A9, as well as their allelic variants, and then change their enzymatic activities in the process of substrate catalysis. The current study was designed to identify this mechanism using morphine as the substrate of UGT2B7. Single-recombinant allozymes, including UGT2B7*1 (wild type), UGT2B7*71S (A71S, 211G>T), UGT2B7*2 (H268Y, 802C>T), UGT2B7*5 (D398N, 1192G>A), and double-recombinant allozymes formed by the dimerization of UGT1A9*1 (wild type), UGT1A9*2 (C3Y, 8G>A), UGT1A9*3 (M33T, 98T>C), UGT1A9*5 (D256N, 766G>A), UGT1A1 (wild type) with its splice variant UGT1A1b were established and incubated with morphine in vitro. Each sample was analyzed with HPLC-MS/MS. All enzyme kinetic parameters were then measured and analyzed. From the results, the production ratio of its aberrant metabolism and subsequent metabolites, morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G), changes regioselectively. Double-recombinant allozymes exhibit stronger enzymatic activity catalyzing morphine than the single-recombinant alloyzymes. Compared to UGT2B7*1, UGT2B7*2 singles or doubles have lower Km values for M3G and M6G, whereas UGT2B7*5 allozymes perform opposite effects. The double allozymes of UGT1A9*2 or UGT1A9*5 with UGT2B7 tend to produce M6G. Interestingly, the majority of single or double allozymes significantly reduce the ratio of M3G to M6G. The UGT1A9*2-UGT2B7*1 double enzyme has the lowest M3G:M6G ratio, reflecting that more M6G would form in morphine glucuronide metabolism. This study demonstrates that UGT2B7 common SNPs and their dimers with UGT1A1 and UGT1A9 and their allelic variants can regioselectively affect the generation of two metabolites of morphine via altering the CLint ratios of M3G to M6G. These results may predict the effectiveness of morphine antinociception in individualized opioid treatment.

Brain-derived neurotrophic factor involved epigenetic repression of UGT2B7 in colorectal carcinoma: A mechanism to alter morphine glucuronidation in tumor.

Uridine diphosphate-glucuronosyltransferase (UGT) 2B7, as one of significant drug enzymes, is responsible on the glucuronidation of abundant endobiotics or xenobiotics. We here report that it is markedly repressed in the tumor tissues of colorectal carcinoma (CRC) patients. Accordingly, morphine in CRC cells will stimulate the expression of its main metabolic enzyme, UGT2B7 during tolerance generation by activating the positive signals in histone 3, especially for trimethylated lysine 27 (H3K4Me3) and acetylated lysine 4 (H3K27Ac). Further study reveals that brain-derived neutrophilic factor (BDNF), a secretory neurotrophin, enriched in CRC can interact and inhibit UGT2B7 by primarily blocking the positive signals of H3K4Me3 as well as activating H3K27Ac on the promoter region of UGT2B7. Meanwhile, BDNF repression attributes to the sensitizations of main core factors in poly-comb repressive complex (PRC) 1 rather than PRC2 as the reason of the depression of SUZ12 in the later complex. Besides that, the productions of two main morphine glucuronides are both increased in the BDNF deficient or TSA and BIX-01294 treated morphine tolerance-like HCT-116 cells. On the same condition, active metabolite, morphine-6-glucuronide (M6G) was accumulated more than inactive M3G. Our findings imply that enzymatic activity enhancement and substrate regioselective catalysis alteration of UGT2B7 may release morphine tolerance under the cure of tumor-induced pain.

siRNA capsulated brain-targeted nanoparticles specifically knock down OATP2B1 in mice: a mechanism for acute morphine tolerance suppression.

Regulating main brain-uptake transporter of morphine may restrict its tolerance generation, then modify its antinociception. In this study, more than 2 fold higher intracellular uptake concentrations for morphine and morphine-6-glucuronide (M6G) were observed in stable expression cells, HEK293-hOATP2B1 than HEK293-MOCK. Specifically, the Km value of morphine to OATP2B1 (57.58 ± 8.90 µM) is 1.4-time more than that of M6G (80.31 ± 21.75 µM); Cyclosporine A (CsA), an inhibitor of OATP2B1, can inhibit their intracellular accumulations with IC50 = 3.90 ± 0.50 µM for morphine and IC50 = 6.04 ± 0.86 µM for M6G, respectively. To further investigate the role of OATP2B1 in morphine brain transport and tolerance, the novel nanoparticles of DGL-PEG/dermorphin capsulated siRNA (OATP2B1) were applied to deliver siRNA into mouse brain. Along with OATP2B1 depressed, a main reduction was found for each of morphine or M6G in cerebrums or epencephalons of acute morphine tolerance mice. Furthermore, calcium/calmodulin-dependent protein kinase IIα (CaMKIIα) in mouse prefrontal cortex (mPFC) underwent dephosphorylation at Thr286. In conclusion, OATP2B1 downregulation in mouse brain can suppress tolerance via blocking morphine and M6G brain transport. These findings might help to improve the pharmacological effects of morphine.

Influences of CYP2D6*10 polymorphisms on the pharmacokinetics of iloperidone and its metabolites in Chinese patients with schizophrenia: a population pharmacokinetic analysis.

AIM: Iloperidone is an atypical antipsychotic drug that is mainly metabolized by CYP2D6, CYP3A4, and cytosolic enzymes. Previous studies show that extensive and poor metabolizers of CYP2D6 exhibit different plasma concentrations of iloperidone and its metabolites. The aim of this study was to develop a parent-metabolite population pharmacokinetic (PPK) model to quantify the effects of CYP2D6*10 allele on the pharmacokinetics of iloperidone and its metabolites in Chinese schizophrenia patients. METHODS: Seventy Chinese schizophrenia patients were enrolled, from whom limited blood samples were collected on d 15 (0 h) and d 28 (0, 4 and 12 h after drug administration). The plasma concentrations of iloperidone and its metabolites M1 (P-88) and M2 (P-95) were simultaneously detected using a validated HPLC-MS assay. CYP2D6*10 (rs1065852) genotyping was performed. A PPK model was developed based on data from the patients using the NONMEM software (version 7.2). A one-compartment model with first-order absorption and elimination was used to describe the pharmacokinetic data related to iloperidone and its metabolites. RESULTS: Patients with the CYP2D6*10 T/T genotype had significantly higher concentrations of iloperidone and M1, and lower concentrations of M2 than the patients with C/C or C/T genotypes. The CYP2D6*10 genotype affected the elimination constants for transformation of iloperidone to the metabolites M1 (K23) and M2 (K24). The K23 value of the patients with T/T genotype was 1.34-fold as great as that of the patients with C/C or C/T genotype. The K24 value of the patients with C/T and T/T genotypes was 0.693- and 0.492-fold, respectively, as low as that of the patients with C/C genotype. CONCLUSION: CYP2D6*10 mutations affect the pharmacokinetics of iloperidone and its metabolites in Chinese schizophrenia patients, suggesting that the clinical doses of iloperidone for patients with CYP2D6*10 mutations need to be optimized.

[Recent advances in the quantification of drug metabolizing enzymes and transporters by proteomic approach].

With the advance of drug development and research techniques, the drug metabolic processes and mechanism can be more deeply achieved. As the drug metabolism and pharmacokinetics process are mediated by drug metabolizing enzymes and transporters, study of drug metabolizing enzymes and transporters has become an important part for drug development. The traditional immunoassays with low sensitivity and poor specificity can not reflect the accurate expression level of drug metabolizing enzymes and transporters. We now give a brief review on the quantitative study of drug metabolizing enzymes and transporters by mass spectrometry-based proteomic approach.

In Silico Analysis and Experimental Validation of Active Compounds from Cichorium intybus L. Ameliorating Liver Injury.

This study aimed at investigating the possible mechanisms of hepatic protective activity of Cichorium intybus L. (chicory) in acute liver injury. Pathological observation, reactive oxygen species (ROS) detection and measurements of biochemical indexes on mouse models proved hepatic protective effect of Cichorium intybus L. Identification of active compounds in Cichorium intybus L. was executed through several methods including ultra performance liquid chromatography/time of flight mass spectrometry (UPLC-TOF-MS). Similarity ensemble approach (SEA) docking, molecular modeling, molecular docking, and molecular dynamics (MD) simulation were applied in this study to explore possible mechanisms of the hepato-protective potential of Cichorium intybus L. We then analyzed the chemical composition of Cichorium intybus L., and found their key targets. Furthermore, in vitro cytological examination and western blot were used for validating the efficacy of the selected compounds. In silico analysis and western blot together demonstrated that selected compound 10 in Cichorium intybus L. targeted Akt-1 in hepatocytes. Besides, compound 13 targeted both caspase-1 and Akt-1. These small compounds may ameliorate liver injury by acting on their targets, which are related to apoptosis or autophagy. The conclusions above may shed light on the complex molecular mechanisms of Cichorium intybus L. acting on hepatocytes and ameliorating liver injury.

Pharmacokinetics of escin Ia in rats after intravenous administration.

ETHNOPHARMACOLOGICAL RELEVANCE: Escin, a natural mixture of triterpene saponins, is commonly utilized for the treatment of chronic venous insufficiency, hemorrhoids, inflammation and edema. Escin Ia is the chief active ingredient in escin and plays key role in mediating its pharmacological effects. Adequate pharmacokinetic data are essential for proper application of escin agent in clinical practice. However, pharmacokinetic properties of escin Ia are still poorly understood and this conflicts with the growing use of escin agent over the years. The goal of this study is to investigate the pharmacokinetic behavior of escin Ia in rats after low, medium and high-dose intravenous administration. MATERIALS AND METHODS: Wistar rats were divided into 3 groups (n=6 per group) and escin Ia was administered via the caudal vein at doses of 0.5, 1.0 and 2.0 mg/kg, respectively. Subsequently, the concentrations of escin Ia and its metabolite isoescin Ia, a positional isomer of escin Ia, in rats׳ plasma were measured by an established liquid chromatography tandem mass spectrometry (LC-MS/MS) method at various time points following the administration of the drug. Main pharmacokinetic parameters were calculated by non-compartmental analysis using the TopFit 2.0 software package (Thomae GmbH, Germany). RESULTS: After intravenous administration, the Cmax and AUC of escin Ia increased in a dose-proportional manner at the dose of 0.5 mg/kg and 1.0 mg/kg, while increased in a more than dose-proportional manner at the doses of 1.0 mg/kg and 2.0 mg/kg. The t1/2 was significantly longer with increased intravenous doses, while other parameters such as CL and Vd also exhibit disagreement among three doses. Taken together, our data showed dose-dependent pharmacokinetic profile of escin Ia in rats after intravenous administration at the doses of 0.5-2.0 mg/kg. After intravenous administration, escin Ia was rapidly and extensively converted to isoescin Ia. CONCLUSIONS: The results suggested dose-dependent pharmacokinetics of escin Ia at the doses of 0.5-2.0 mg/kg after intravenous administration. Escin Ia is isomerized to isoescin Ia rapidly and extensively regardless of the doses.

[Fragmentation pathways of five estrogens using electrospray ionization quadrupole time-of-flight mass spectrometry].

The fragmentation pathways of five estrogens (estradiol, estrone, equilin sulfate, 17 a-dihydroequilin sulfate and equilenin sulfate) have been studied with high resolution and high mass accuracy using electrospray ionization quadrupole time-of-flight mass spectrometry (ESI-Q-TOF/MS) in the negative ion mode. Molecular weights were obtained from [M-H](-) ions in the product ion spectra. The results indicate that the five structurally similar estrogens have similar fragmentation pathways. Using their stable isotope forms as internal reference compounds, the accurate mass and composition of the fragment ions were determined. During collision-induced dissociation (CID), cleavage is initiated by loss of oxygen atoms from carbon-17, after which D and C rings cleave sequentially and rearrange to finally form stable conjugate structures with highly abundant characteristic fragment ions at m/z 183 (accompanied by m/z 181), m/z 169 and m/z 145 (accompanied by m/z 143). Understanding these characteristic fragmentation pathways of estrogens will be helpful in identifying the structures of steroid hormones in general.

Hepatoprotective effect of Cichorium intybus L., a traditional Uighur medicine, against carbon tetrachloride-induced hepatic fibrosis in rats.

AIM: To investigate the hepatoprotective effect of a Cichorium intybus L. extract (CIE) on CCl4-induced hepatic fibrosis in rats. METHODS: Seventy-two male Wistar albino rats were randomly divided into six groups of twelve rats each. The normal control group was allowed free access to food and water. Liver injury was performed in the remaining five groups with an i.p. injection of a 1.0 mL/kg CCl4 and olive oil (2:3 v/v) mixture, twice weekly for 8 weeks. All rats, with the exception of the injury model group, were intragastrically (i.g.,) administered quantum satis (q.s.) dosages [CIE group: 6, 18, and 54 mg/kg, respectively; Fu Fang Bie Jia Ruan Gan Pian (FFBJRGP) group: 780 mg/kg]. The oral administration of different drugs was performed on the day before CCl4 administration and subsequently once per day for 8 wk. The serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), hexadecenoic acid (HA), laminin (LN), hydroxyproline (Hyp), and glutathione (GSH), malondialdehyde (MDA) and superoxide dismutase (SOD) in the rat livers were measured. Histopathological changes in the liver were assessed for each group using HE staining and a Masson Trichrome examination. The expression of transforming growth factor-ß1 (TGF-ß1) and α-smooth muscle actin (α-SMA) was examined by immunohistochemical analysis. RESULTS: CIE at oral doses of 6, 18, and 54 g/kg per day showed a significant hepatoprotective effect, especially at a dose of 54 g/kg per day. CIE doses reduced the levels of AST (149.04 ± 34.44, P < 0.01), ALT (100.72 ± 27.19, P < 0.01), HA (548.50 ± 65.09, P < 0.01), LN (28.69 ± 3.32, P < 0.01) and Hyp (263.33 ± 75.82, P < 0.01). With regards to hepatoprotective activity, the CIE dose of 54 g/kg per day produced the largest significant effect by increasing GSH (3.11 ± 0.81), SOD (269.98 ± 33.77, P < 0.01) and reducing MDA (2.76 ± 0.51, P < 0.01) levels in the liver. The expressions of TGF-ß1 and α-SMA were measured by immunohistology and found to be significantly reduced by CIE in a dose-dependent manner. CONCLUSION: CIE may effectively protect against CCl4-induced hepatic fibrosis in rats; thus, it is a promising anti-fibrotic therapeutic agent.

Comparative pharmacokinetics and the bioavailability of escin Ib and isoescin Ib following the administration of escin, pure escin Ib and isoescin Ib in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Adequate pharmacokinetic data of escin, a natural mixture of triterpene saponins used for the treatment of chronic venous insufficiency, hemorrhoids, inflammation and edema, is of special interest in view of the growing use of escin agent in clinical medicine. However, pharmacokinetic data are inadequate to support their clinical indication. Escin Ib and isoescin Ib are the chief active ingredients in escin, pharmacokinetics study of them would be helpful for improving the practice of escin application. The goals of this study are to determine the plasma concentration of escin Ib and isoescin Ib using an established liquid chromatography tandem mass spectrometry (LC-MS/MS) method and to compare the pharmacokinetics and bioavailability of these compounds in rats when administered as pure isomers or as sodium escinate. MATERIALS AND METHODS: Five groups of Wistar rats (n=6 per group) were treated with either an intravenous (IV) dose (2.78mg/kg) of sodium escinate (corresponding to 0.5mg/kg of escin Ib and 0.5mg/kg of isoescin Ib), an IV dose (0.5mg/kg) and an oral dose (4mg/kg) of pure escin Ib or isoescin Ib. The concentrations of escin Ib and isoescin Ib in rat plasma were determined by LC-MS/MS at various times following the administration of the drugs. The pharmacokinetic parameters were estimated by a non-compartmental analysis and then subjected to statistical analysis. RESULTS: The administration of sodium escinate, which contains the two isomers, gave rise to higher terminal phase half-life (t1/2) and mean residence time (MRT) values for both escin Ib and isoescin Ib compared to the corresponding compounds administered alone. The absorption of escin Ib and isoescin Ib was very poor, with the oral bioavailability (F) values of <2% observed for both compounds. The two compounds were found to isomerize in vivo, wherein the conversion of escin Ib to isoescin Ib was much easier than that of isoescin Ib to escin Ib. CONCLUSIONS: A comparison of the pharmacokinetics of escin Ib and isoescin Ib administered alone and together in rats suggests that the administration of herbal preparations of escin in a clinical setting may result in a longer duration of action than the administration of each isomer alone. The interconversion of escin Ib and isoescin Ib when administered alone indicates that the administration of one isomer results in exposure to the other isomer.

[Comparative study on pharmacokinetics of gentiopicroside and gentianae radix extract in rats].

OBJECTIVE: To compare the pharmacokinetics of gentiopicroside and Gentianae Radix extract in rats and assess the effect of other components in Gentianae Radix on the pharmacokinetics of gentiopicroside. METHODS: The rats were oral administrated with gentiopicroside and Gentianae Radix extract, the content of geritiopicroside was chosen as index and determined by HPLC. The pharmacokinetic parameters were calculated with DAS 2.1.1 program. RESULTS: The concentration-time curve of gentiopicroside and Gentianae Radix extract was described by two compartment model. The main pharmacokinetic parameters of gentiopicroside and Gentianae Radix extract were: C(max) (16.53 +/- 0.37) g/mL and (16.61 +/- 0.49) g/mL, T(max) 0.25 h and 1.5 h, t1/2(alpha) (0.20 +/- 0.04) h and (0.69 +/- 0. 14) h, t /2 (beta) (0.64 +/- 0.08) hand (0.80 +/- 0.11) h, AUC(0-infinity) (18.20 +/- 1.97) g x h/mL and (39.20 +/- 1.18) g x h/mL, CL( 2.75 +/- 0.32) L/(h x kg) and (1.22 +/- 0.04) L (h x kg), respectively. CONCLUSION: There are significantly differences in pharmacokinetic parameters between gentiopicroside and Gentianae Radix extract in rats.

A highly selective probe for human cytochrome P450 3A4: isoform selectivity, kinetic characterization and its applications.

Bufalin 5ß-hydroxylation was found to be an isoform-specific biotransformation probe substrate for cytochrome P450 3A4 (CYP3A4). The probe reaction was well-characterized and it can be used for measuring the real catalytic activities of CYP3A4 from different enzyme sources.

Determination of thalidomide concentration in human plasma by liquid chromatography-tandem mass spectrometry.

A rapid, sensitive and specific analytical method based on high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed for the determination of thalidomide concentration in human plasma. The analyte and internal standard were extracted by liquid-liquid extraction with ether-dichloromethane (3:2, v/v) and separated on a TC-C(18) column using methanol-10 mM ammonium acetate-formic acid (60:40:0.04, v/v/v) as the mobile phase at a flow rate of 0.9 ml/min. The detection was performed using an API 4000 triple quadrupole mass spectrometer in the positive electrospray ionization (ESI) mode and completed within 3.0 min. The multiple reaction monitoring (MRM) transitions were m/z 259.1→84.0 for the analyte and m/z 195.9→138.9 for temozolomide. The calibration curve exhibited a linear dynamic range of 2-1500 ng/ml (r>0.9991). The intra-and inter-day precisions (as relative standard deviation; RSD) were 6.8-13.5% and 4.3-5.0% respectively and the accuracy (as relative error; RE) was 2.0-3.5%. The recoveries and matrix effects were satisfactory in all the biological matrices examined. This method was successfully used in a pharmacokinetic study of thalidomide in healthy male volunteers receiving an oral administration of a 200-mg dose.

Quantitation of bivalirudin, a novel anticoagulant peptide, in human plasma by LC-MS/MS: Method development, validation and application to pharmacokinetics.

A rapid and sensitive method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the determination of a novel anticoagulant peptide bivalirudin in human plasma has been developed and validated. Plasma samples were precipitated protein with acetonitrile and re-extracted with dichloromethane, after which the analyte and triptorelin as an internal standard (IS) were separated on a 300SB-C18 column (150 mm×4.6 mm i.d., 5 µm particle size) using 0.1% formic acid:methanol (45:55, v/v) as mobile phase. The triple-quadrupole mass spectrometer, equipped with electrospray ionization (ESI) interface, was operated in the positive ion mode, and the multiple-reaction monitoring (MRM) transitions of bivalirudin and IS were at m/z 1091.0→650.4 and m/z 656.5→249.3, respectively. The lower limit of quantification (LLOQ) was 1 ng/mL for 100 µL plasma sample and the assay was linear over the concentration range 1-1000 ng/mL. The accuracy was within a range from -0.4% to 0.5% in terms of relative error (RE) and the intra- and inter-day precisions in terms of relative standard deviation (RSD) were ≤2.92 and ≤3.36, respectively. The method was successfully applied to a pharmacokinetic study involving intravenous administration of bivalirudin (0.5 mg/kg) to Chinese volunteers.

[Fragmentation behaviors of taxanes drugs using electrospray ionization with quadrupole time-of-flight mass spectrometry].

The fragmentation pathways of two taxanes drugs have been studied in positive ion mode by Q-TOF with the advantages of high mass accuracy and high resolution analysis. The [M+H] + ions were observed by ESI-MS, from which the molecular weights were obtained. Using the protonated pseudo-molecular ions [M+H]+ as internal reference compounds, the accurate mass and element composition of the fragment ions were determined. The collision induced dissociation (CID) data of the [M+H] ions provided fragmentation pathways of related compounds. Results showed that the major cleavage pathways of paclitaxel and docetaxel were the same that the cleavage of C-O bond between the side chain and taxol skeleton easily occurred, then stripping of the functional groups on the parent ring. Some common fragments were formed, such as m/z 105.033 7, 291.137 3, 309.148 5, 327.159 7, 387.181 2 and 509.217 4, which would provide a basis for future qualitative and quantitative analysis of taxanes in vitro and in vivo.

Pharmacokinetics and bioavailability of cimicifugosides after oral administration of Cimicifuga foetida L. extract to rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Cimicifuga foetida L., a traditional Chinese medicine, has been used as an anti-inflammatory, antipyretic and analgesic remedy. The primary active constituents are believed to be present in the triterpene glycoside fraction. MATERIALS AND METHODS: To develop an LC-MS/MS assay for four major cimicifugosides [cimicifugoside H-1 (Cim A), 23-epi-26-deoxyactein (Cim B), cimigenolxyloside (Cim C) and 25-O-acetylcimigenoside (Cim D)] obtained from C. foetida L. and apply it to investigate their pharmacokinetic (PK) properties and bioavailabilities through oral administration of C. foetida L. extract (12.5, 25 and 50mg/kg) and single intravenous (i.v.) doses (5mg/kg) of the individual cimicifugosides in rat. PK parameters were estimated by non-compartmental analysis. RESULTS: All calibration curves showed excellent linear regressions (all r>0.995) within the range of tested concentrations. The intra- and inter-day variations were <15% in terms of RSD. The molar ratio of Cims A, B, C, and D in the extract was 20.7:1.4:2.9:1. PK parameters for Cims A, B, C, and D following oral administration of the extract were respectively: C(max) 4.05-17.69, 90.93-395.7, 407.1-1180 and 21.56-45.09pmol/mL; T(max) 0.46-1.28, 2.00-4.67, 14.67-19.67 and 8.08-14.27h; absolute oral bioavailability (F) 1.86-6.97%, 26.8-48.5%, 238-319% and 32.9-48%. PK parameters after i.v. administration of individual cimicifugosides were respectively: elimination half-life 1.1, 2.5, 5.7 and 4.2h; clearance 15.7, 0.48, 0.24 and 1.13mL/hkg. CONCLUSIONS: Systemic exposure to Cims B, C and D following oral administration of the extract was significantly greater than to Cim A despite the predominance of Cim A in the extract. Significantly different clearance and interconversion from Cim A to Cim C probably accounts for the different exposure to the four cimicifugosides.

Comparative pharmacokinetics and bioavailability of escin Ia and isoescin Ia after administration of escin and of pure escin Ia and isoescin Ia in rat.

ETHNOPHARMACOLOGICAL RELEVANCE: Escin Ia and isoescin Ia have been traditionally used clinically as the chief active ingredients of escin, a major triterpene saponin isolated from horse chestnut (Aesculus hippocastanum) seeds for the treatment of chronic venous insufficiency, hemorrhoids, inflammation and edema. AIM OF THE STUDY: To establish a sensitive LC-MS/MS method and investigate the pharmacokinetic properties of escin Ia and isoescin Ia in rats and the pharmacokinetics difference of sodium escinate with pure escin Ia and isoescin Ia. The absolute bioavailability of escin Ia and isoescin Ia and the bidirectional interconversion of them in vivo were also scarcely reported. MATERIALS AND METHODS: Wister rats were administrated an intravenous (i.v.) dose (1.7 mg/kg) of sodium escinate (corresponding to 0.5mg/kg of escin Ia and 0.5mg/kg of isoescin Ia, respectively) and an i.v. dose (0.5mg/kg) or oral dose (4mg/kg) of pure escin Ia or isoescin Ia, respectively. At different time points, the concentrations of escin Ia and isoescin Ia in rat plasma were determined by LC-MS/MS method. Main pharmacokinetic parameters including t(1/2), MRT, CL, V(d), AUC and F were estimated by non-compartmental analysis using the TopFit 2.0 software package (Thomae GmbH, Germany) and statistical analysis was performed using the Student's t-test with P<0.05 as the level of significance. RESULTS: After administration of sodium escinate, the t(1/2) and MRT values for both escin Ia and isoescin Ia were larger than corresponding values for the compounds given alone. Absorption of escin Ia and isoescin Ia was very low with F values both <0.25%. Escin Ia and isoescin Ia were found to form the other isomer in vivo with the conversion of escin Ia to isoescin Ia being much extensive than from isoescin Ia to escin Ia. CONCLUSION: Comparison of the pharmacokinetics of escin Ia and isoescin Ia given alone and together in rat suggest that administration of herbal preparations of escin for clinical use may provide longer duration of action than administration of single isomers. The interconversion of escin Ia and isoescin Ia when given alone indicates that administration of one isomer leads to exposure to the other.

[Multidimensional spatial triangular area as an index for the evaluation of the release-absorption correlation of multiple component traditional Chinese medicines].

The paper is aimed to provide a novel index, named as multidimensional spatial triangular area, for the evaluation of the release-absorption correlation of multiple component traditional Chinese medicines (TCMs). The applicability of the method was demonstrated by the example data. The method and standard practice for evaluation of the release-absorption correlation for western medicines with single compound could not be applied to TCMs with multiple components. The release percentage or absorption percentage of the multiple components for TCMs at the sampling time was a point in the multidimensional space. The area of the triangle formed byt the sequential three points represented the changing characteristics of the components' release and absorption kinetics. The side lengths of the triangle could be calculated from the spatial distances between each two of the sequential three points. Then the triangle area could be obtained by the side lengths. The in vitro release-in vivo absorption correlation of the multiple components could be represented by the correlation between the integrating values of the release triangle areas and that of the absorption triangle areas. The results of the examples indicated that the multidimensional spatial triangular area method could treat the multiple components in a holistic way, in line with the holism the hi he TCMs. Therefore, the multidimensional spatial triangular area method provided new methodology for the release-absorption correlation of the TCMs with multiple components.