Ke Lan

Intra-herb pharmacokinetics interaction between quercetin and isorhamentin.

AbstractAim:Quercetin and isorhamnetin are common constituents of some herb extracts, such as extracts of gingko leaves and total flavones of Hippophae rhamnoides L. The intra-herb pharmacokinetics interactions between isorhamnetin and quercetin were investigated in the present study.Methods:Human MDR1 cDNA transfected MDCKII cells were used to validate whether isorhamnein interacted with P-gp. Caco-2 transport assays and a randomized, 3-way crossover pharmacokinetics study in rats were used to investigate the pharmacokinetics interactions. HPLC was used to determine cell transport samples. The total plasma concentrations of quercetinand isorhamnetin were determined by liquid chromatography tandem mass spectrometry (LC-MS/MS) by treatment with β-glucuronidase and sulfatase.Results:The permeability ratio (absorptive permeability/secretive permeability) of isorhamnetin across human MDR1 cDNA transfected MDCKII cells, Caco-2 cells and wild-type MDCKII cells are 0.25±0.02, 0.74±0.05, and 1.41±0.06, respectively. This result proved the role of P-gp in the cell efflux of isorhamnetin. While co-transporting with each other across Caco-2 cells monolayer, the permeability ratio of isorhamnetin and quercetin increased by 4.3 and 2.2 times. After coadministration with each other to rats, the Cmax, AUC0–72 h, and AUC0–∞ of both isorhamnetin and quercetin significantly increased compared with single administration.Conclusion:The above results proved intra-herb pharmacokinetics interaction between quercetin and isorhamentin. P-gp might play an important role, whereas other drug efflux pumps, such as multi-drug resistance associate protein 2 and breast cancer resistance protein, might be involved. Accordingly, besides the drug-herb interactions, intra-herb interaction might be brought into view with the wide use of herbal-based remedies.

Reduced system exposures of total rhein and baicalin after combinatory oral administration of rhein, baicalin and berberine to beagle dogs and rats

ETHNOPHARMACOLOGICAL RELEVANCE Rhein (Rh), baicalin (BG) and berberine (Be) are important coexisted constituents of San-Huang-Xie-Xin-Tang, which was widely used in traditional Chinese medicine for the treatment of gastritis, hypertension, gastric bleeding and peptic ulcers, etc. AIM OF THE STUDY Based on the extensive phase II conjugation reactions of polyphenols (Rh and BG) in vivo, the aims of the present study were to investigate the effects of combination (Rh, BG and Be) on the system exposures of total Rh and BG involving the phase II conjugates metabolites and its possible mechanism. MATERIALS AND METHODS A 3×3 Latin square single heavy design was used to investigate the pharmacokinetics influence of total Rh and BG after combination of Be by treating plasma samples with β-glucuronidase/sulfatase both in beagle dogs and Wistar rats. In vitro and in situ experiment models including in situ rat intestinal perfusion, Caco-2 cell monolayer transport and small intestinal flora incubation system were used to discuss the possible mechanism. RESULTS The results of pharmacokinetic interactions showed that combination significantly reduced the system exposures of total Rh and BG. Compared with Rh or BG alone, the mean area under concentration-time curves (AUC(0-t)) of total Rh and BG reduced by 31% and 77% in beagle dog experiment. In Wistar rat experiment, the AUC(0-t) of total Rh and BG reduced by 22% and 21%. Subsequently, the results of in situ rat intestinal perfusion and small intestinal flora incubation system tests revealed that combination may decrease the absorption and metabolism of BG. However, combination could not affect the transport profile of BG across the Caco-2 cell. Moreover, combination did not affect the absorption or metabolism profile of Rh in all three in situ/in vitro experiments. CONCLUSIONS It was deduced that the possible mechanism of the reduction of the system exposures of total Rh and BG was related to that combination decreased the metabolism of BG to B or the phase II conjugates of Rh/BG excreted from liver/bile duct to their free aglycones in vivo by inhibiting intestinal flora. The potent effects of combination on the phase II conjugates of Rh and B in pharmacokinetics, shown in this paper, indicated that more attention should be paid to the phase II conjugates metabolites of these polyphenols (undergo extensive phase II conjugation reactions in vivo) when applied herbal products composed of these coexist compounds.

Bioequivalence of a single 10-mg dose of finasteride 5-mg oral disintegrating tablets and standard tablets in healthy adult male Han Chinese volunteers: a randomized sequence, open-label, two-way crossover study.

BACKGROUND Finasteride, an inhibitor of the steroid 5alpha-reductase, has been approved for the treatment of benign prostatic hyperplasia and androgenetic alopecia. An orally disintegrating tablet (ODT) 5-mg formulation of finasteride was recently developed. Information regarding its pharmacokinetics and bioequivalence was required to assess the efficacy and safety of this formulation before marketing it in China. OBJECTIVES The aims of this study were to compare the bioavailability of finasteride ODTs and standard tablets in healthy adult male Han Chinese volunteers and to determine whether any observed differences exceeded Chinese regulatory guidelines for bioequivalence. METHODS This single-dose, randomized, open-label, 2-way crossover trial was conducted in China. Healthy adult male Han Chinese volunteers were enrolled. Participants were randomly assigned to receive 10 mg of either the ODT or standard tablet formulation, followed by a 1-week washout period and administration of the alternate formulation. Doses were administered after a 12-hour overnight fast. For analysis of pharmacokinetic properties, including C(max), AUC(0-24), and AUC(0-infinity), blood samples were obtained at 0.5, 0.75, 1, 1.5, 2, 2.5, 3, 5, 8, 11, 14, and 24 hours after administration. The formulations were to be considered bioequivalent if calculations of the 90% CI for the ratio of the means of the measures for the test and reference formulations fell within bioequivalence limits, 80% to 125%, for logarithmic (log) transformation of C(max) and AUC, and if Schuirmanns two 1-sided tests showed P < 0.05. Tolerability was assessed using vital sign measurements (ie, blood pressure, body temperature, heart rate, and respiratory rate), laboratory analysis (ie, hematology, blood biochemistry, hepatic function, and urinalysis), and interviews with participants. RESULTS Twenty-four men (mean [SD] age, 22.0 [1.2] years [range, 20-24 years]; weight, 63.5 [4.6] kg [range, 55-70 kg]; height, 172.8 [4.4] cm [range, 164-180 cm]) were enrolled in this study, and 24 (12 each randomized to receive the ODT or standard tablet first) completed it. No period or sequence effects were observed. The 90% CIs for the log-transformed C(max), AUC(0-24), and AUC(0-infinity) values were 86.8 to 106.8, 95.1 to 119.1, and 96.2 to 117.5, respectively (all, P < 0.05). The Wilcoxon rank sum test of T(max) found a significant difference between the ODT formulation (mean [SD], 2.40 [0.47] hours) and standard tablet formulation (1.98 [0.63] hours). No adverse events were reported by the volunteers or found in clinical laboratory testing during the study. CONCLUSIONS In this single-dose study, based on the rate and extent of absorption, the ODT (ie, test) and standard tablet (ie, reference) formulations of finasteride met the regulatory criteria for bioequivalence in these fasting healthy adult male Han Chinese volunteers. However, a significant difference was found for T(max) between the test and reference formulations. Both formulations were well tolerated. ClinicalTrials. gov identifier: 2005L02216.

Metabolic profiling assisted quality assessment of Rhodiola rosea extracts by high-performance liquid chromatography

In this work, fast and sensitive high-performance liquid chromatography (HPLC) coupled with multivariate analysis was utilized to assist the quality assessment of Rhodiola rosea extracts (RREs). 131 peaks were separated and detected in RREs on a fused-core C18 column. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) of the chromatographic data demonstrated that 10 batches of RREs could be well-differentiated and categorized into three groups which were closely related to the origins of RREs. Partial least square-discriminant analysis (PLS-DA) showed that the quality differentiation might be explained by at least 6 components, in which rosavin was characterized by an external reference, rosiridine was identified by liquid chromatography-mass spectrometry (LC-MS), and the mass spectra of the others were provided. The observation that the level of rosavin was more relevant to the multivariate chromatographic data than the ones of salidroside and tyrosol, the other two components commonly used to standardize RREs, was confirmed by the PLS prediction models. Results of the present study not only indicated that rosavin was a rational marker to represent the quality of RREs, but also demonstrated the power of HPLC-based metabolic profiling in the quality assessment of herbal extracts.

Simultaneous determination of six herbal components in intestinal perfusate by high-performance liquid chromatography.

An effective, accurate and reliable HPLC with UV detection method was developed and validated for quantitation of six components: baicalin, berberine hydrochloride, quercetin, kaempferol, isorhamnetin and baicalein in intestinal perfusate using rotundin as an internal standard. The chromatographic separation was performed on a Welchrom-C(18) column (250 x 4.6 mm i.d. with 5.0 microm particle size) with a mobile phase consisting of acetonitrile, water, phosphoric acid and triethylamine (30:70:0.2:0.1,v/v) at a flow rate of 1.0 mL/min and a UV detection at 270 nm. The method had a chromatographic run time of 30 min and excellent linear behavior over the investigated concentration ranges observed with the values of r higher than 0.99 for all the analytes. The lower limit of quantification of the analytical method was 0.09 microg/mL for berberine hydrochloride, quercetin, kaempferol and baicalein and 0.18 microg/mL for baicalin and isorhamnetin. The intra- and inter-day precisions measured at three concentration levels were all less than 10% for all analytes. The bias ranged from -6.91 to 4.33%. The validated method has been successfully applied to investigate the rat intestine absorption profiles of baicalin, berberine hydrochloride, quercetin, kaempferol, isorhamnetin and baicalein.

A chemical profiling strategy for semi-quantitative analysis of flavonoids in Ginkgo extracts

Flavonoids analysis in herbal products is challenged by their vast chemical diversity. This work aimed to develop a chemical profiling strategy for the semi-quantification of flavonoids using extracts of Ginkgo biloba L. (EGB) as an example. The strategy was based on the principle that flavonoids in EGB have an almost equivalent molecular absorption coefficient at a fixed wavelength. As a result, the molecular-contents of flavonoids were able to be semi-quantitatively determined by the molecular-concentration calibration curves of common standards and recalculated as the mass-contents with the characterized molecular weight (MW). Twenty batches of EGB were subjected to HPLC-UV/DAD/MS fingerprinting analysis to test the feasibility and reliability of this strategy. The flavonoid peaks were distinguished from the other peaks with principle component analysis and Pearson correlation analysis of the normalized UV spectrometric dataset. Each flavonoid peak was subsequently tentatively identified by the MS data to ascertain their MW. It was highlighted that the flavonoids absorption at Band-II (240-280 nm) was more suitable for the semi-quantification purpose because of the less variation compared to that at Band-I (300-380 nm). The semi-quantification was therefore conducted at 254 nm. Beyond the qualitative comparison results acquired by common chemical profiling techniques, the semi-quantitative approach presented the detailed compositional information of flavonoids in EGB and demonstrated how the adulteration of one batch was achieved. The developed strategy was believed to be useful for the advanced analysis of herbal extracts with a high flavonoid content without laborious identification and isolation of individual components.

Comparative single- and multiple-dose pharmacokinetics of rosuvastatin following oral administration in Chinese volunteers

SummaryThe objective of this study was to determine and compare the plasma concentrations of rosuvastatin following single- and multiple-dose administration in Chinese volunteers. The study was of an open label, randomized, three-way cross-over design and was conducted in 12 subjects. Single dose administration of the rosuvastatinon was characterized by a rapid absorption (2.045±0.891 h, 2.273±1.009 h and 1.667±0.651 h) and a marked peak plasma concentration (9.938±4.438, 28.09±12.075 and 43.092±22.09 ng/ml) for the three different doses (5mg, 10mg and 20mg)of rosuvastatin. The apparent elimination half-life amounted to 7.914±3.813 h, 8.445±4.994 h and 15.401±5.429 h following administration, respectively. Similar findings were obtained after multiple dosing. A rapid absorption (3±1.365 h, 3.042±1.054 h and 2.375±0.829 h) and a marked peak plasma concentration (9.288±5.314, 18.808±6.687 and 49.808±23.516 ng/ml) for the three different doses (5mg, 10mg and 20 mg) of rosuvastatin were observed. The apparent elimination half-life amounted tol3.181±5.492 h, 8.035±3.331 h and 15.509±6.43 h following administration, respectively. Small differences in gender are not considered clinically relevant, and dose adjustments based on gender are not anticipated. But the state of fed or fasting will affect the pharmacokinetic of rosuvastatin.

Characterizations of the hydrolyzed products of ginkgolide A and ginkgolide B by liquid chromatography coupled with mass spectrometry

Ginkgolides are diterpenoid trilactones responsible for the neuromodulatory properties of Ginkgo biloba extracts. They are to be hydrolyzed in aqueous solutions as mixed carboxylate forms potentially including three monocarboxylates, three dicarboxylates and one tricarboxylate. Characterizations of the hydrolyzed products are challenging because there is no way to prepare them individually. In this work, the major hydrolyzed products of ginkgolide A (GA) and ginkgolide B (GB) including all three monocarboxyaltes have been produced in buffers and subjected to liquid chromatography coupled with triple quadrupole MS and LTQ Orbitrap MS analysis. With the comparative analysis of the trilactone of GA and GB, it was highlighted a unique charge-driven fragmentation pathway of twice neutral losses of CO on the lactone-C. The monocarboxylates were accordingly identified based on the construction of their fragmentation pathways cross-linked with those of the trilactone. In brief, the lactone-C hydrolyzed product is characteristic of the absence of product ions between [M-H](-) and [M-H-C2H2O3](-) (m/z 351 for GA and m/z 367 for GB). The featured fragmentation pathway of the lactone-F hydrolyzed product is the cleavage of ring-A, yielding a fragment (m/z 295 for GA and m/z 309 for GB) followed with twice (GA) or triple (GB) neutral losses of CO. The most characteristic fragment of the lactone-E hydrolyzed product is [M-H-H2O-CO2-2CO](-) (m/z 307 for GA and m/z 323 for GB) in contrast to the other two monocarboxylates. The knowledge gained in this work was of special uses to investigate the biological fates and the corresponding pharmacological mechanisms of ginkgolides.

Animal Pharmacokinetic/Pharmacodynamic Studies (APPS) Reporting Guidelines

Animal pharmacokinetic/pharmacodynamic studies are commonly used to provide meaningful preclinical information that can be utilized by the scientific community to conduct first-in-human studies. Poor presentation and interpretation of the data limit study reproducibility, and may result in rejection when the study is submitted to a journal, leading to loss of time and resources at multiple levels. In addition, inconsistencies in reporting the results of animal studies may limit the ability to extrapolate the experimental findings to humans. A few guidelines have been published to make the reporting of animal studies consistent; however, strict implementation of these guidelines by authors, reviewers, and journal editors is still lacking. In an attempt to make the reporting of animal pharmacokinetic/pharmacodynamic studies consistent and improve the standard of reporting, this article provides guidelines that can be followed when submitting such studies to a journal. A detailed checklist, based on these guidelines, has been developed that can be used by the authors, reviewers, and editors to check if the required information is included in the manuscript. These guidelines can also be used for designing and performing such studies.