Evaluation of herb-drug interaction of ambrisentan with shikonin based on UPLC-MS/MS.

CONTEXT: Ambrisentan is an oral endothelin-receptor antagonist (ERA). However, there is no report on the interaction between ambrisentan and shikonin. OBJECTIVE: To investigate the effect of shikonin on ambrisentan metabolism in vivo and in vitro. MATERIALS AND METHODS: This study developed an ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for simultaneous determination of ambrisentan and (S)-4-hydroxymethyl ambrisentan in rat plasma. Twelve male Sprague-Dawley (SD) rats were divided into two groups (n = 6): the control group and shikonin (20 mg/kg) group. The pharmacokinetics of ambrisentan (2.5 mg/kg) were investigated after 30 min. Additionally, human and rat liver microsomes were used to investigate the herb-drug interaction. RESULTS: The UPLC-MS/MS method was shown to be accurate, precise and reliable, and was successfully applied to the herb-drug interaction study of ambrisentan with shikonin. When co-administrated with 20 mg/kg shikonin, the Cmax and AUC(0-∞) of ambrisentan were significantly increased by 44.96 and 16.65%, respectively (p < 0.05). In addition, there were modest decreases in (S)-4-hydroxymethyl ambrisentan Cmax and AUC(0-∞) in the presence of shikonin (p < 0.05), which indicated that these results were in accordance with the inhibition of shikonin on ambrisentan metabolism. Moreover, enzyme kinetic study indicated that shikonin had an inhibitory effect on human and rat microsomes where the IC50 values of shikonin were 5.865 and 6.358 µM, respectively. CONCLUSIONS: Our study indicated that shikonin could inhibit ambrisentan metabolism. Further studies need to be carried out to verify whether similar interaction truly apply in humans and whether this interaction has clinical significance.

Quantitative determination of characteristic components from compound of Lysionotus pauciflorus Maxim. by LC-MS/MS and its application to a pharmacokinetic study.

Tuberculosis of cervical lymph nodes is called scrofula in Traditional Chinese Medicine (TCM). Clinical manifestation is that unilateral or bilateral neck can have multiple enlarged lymph nodes of different sizes. Current therapeutic drugs include Lysionotus pauciflorus Maxim. tablets and compound of Lysionotus pauciflorus Maxim., which have a significant effect on tuberculosis of cervical lymph nodes. This compound is composed of three herbs, Lysionotus pauciflorus Maxim., Prunella vulgaris L. and Artemisia argyi Levl.et Vant. A selective and sensitive LC-MS/MS method was established and validated in rat plasma for the first time. Chromatographic separation was achieved on a Wonda Cract ODS-2 C18 Column (150 mm × 4.6 mm, 5 µm). The mobile phase contained 0.1% formic acid aqueous solution and acetonitrile with a flow rate of 0.8 mL/min. The detection was performed in negative electrospray ionization mode and the precursor/product ion transitions of six components and internal standard (IS) sulfamethoxazole were quantified in multiple reaction monitoring (MRM) using QTRAP-3200 MS/MS. The method fulfilled US Food and Drug Administration guidelines for selectivity, sensitivity, accuracy, precision, matrix effect, extraction recovery, dilution integrity, and stability. This proposed method was then successfully applied to a pharmacokinetic study after oral administration of 10 mL/kg compound extracts in rats. The pharmacokinetic parameters and plasma concentration-time profiles would prove valuable in pre-clinical and clinical investigations on the disposition of compound medicine.

Comparison of Blood Profiles of γ-Oryzanol and Ferulic Acid in Rats after Oral Intake of γ-Oryzanol.

γ-Oryzanol (OZ), a bioactive phytochemical abundant in cereals such as rice, has been reported to be mainly hydrolyzed to ferulic acid (FA) in the body. Meanwhile, in our previous study, we revealed that a part of OZ is absorbed into the body and exists in its intact form. However, the comprehensive absorption profile of OZ and its metabolites (e.g., FA) after OZ intake has not been fully elucidated yet. Therefore, in this study, we measured the concentrations of OZ, FA, and FA conjugates (i.e., FA sulfate and glucuronide) in the blood of rats with the use of HPLC-MS/MS after a single oral administration of 300 µmol/kg body weight of rice bran OZ (RBOZ). As a result, intact OZ along with FA and FA conjugates existed in the blood, which implied that these constituents may all contribute to the physiological effects under OZ intake. Additionally, when an equimolar amount of FA (300 µmol/kg body weight) was administered, it was found that the absorption profile of FA was significantly different from that when RBOZ was administered.

Presence of orally administered rice bran oil γ-oryzanol in its intact form in mouse plasma.

Although the beneficial effects (e.g., lipid-lowering activity) of γ-oryzanol (OZ), a mixture of ferulic acid esters of plant sterols and triterpene alcohols, have been extensively investigated, few studies have evaluated the absorption and metabolism of OZ. Moreover, it is unclear whether OZ, once ingested, is directly absorbed by the intestine into the bloodstream at a sufficient level to exhibit activity. Here, we prepared OZ concentrate from purified rice bran oil (Rice Oil OZ), determined the concentration of OZ in the preparation (cycloartenyl ferulate equivalent concentration; 52.2%), and then carried out chromatography-mass spectrometry analysis of plasma samples from mice after oral administration of Rice Oil OZ. The OZ concentrations of plasma from the control (vehicle-treated) mice were low (trace levels); however, at 5 h after a single oral administration of the Rice Oil OZ (600 mg per kg body weight), the levels significantly increased, reaching 17.6 ng mL-1 for cycloartenyl ferulate, 28.2 ng mL-1 for 24-methylenecycloartanyl ferulate isomers, 15.6 ng mL-1 for campesteryl ferulate, and 5.1 ng mL-1 for ß-sitosteryl ferulate, respectively, expressed in equivalence of cycloartenyl ferulate in plasma. These results provided the first mass spectrometric evidence suggesting that a portion of orally administered OZ is directly absorbed by the intestine and is present in the intact form in plasma. The presence of a significant amount of OZ in its intact form in plasma may explain the beneficial effects of OZ in vivo.

The effect of induction of CYP3A4 by St John's wort on ambrisentan plasma pharmacokinetics in volunteers of known CYP2C19 genotype.

To evaluate the impact of CYP2C19 polymorphisms on ambrisentan exposure and to assess its modification by St. John's wort (SJW), 20 healthy volunteers (10 CYP2C19 extensive, four poor and six ultrarapid metabolizers) received therapeutic doses of ambrisentan (5 mg qd po) for 20 days and concomitantly SJW (300 mg tid po) for the last 10 days. To quantify changes of CYP3A4 activity, midazolam (3 mg po) as a probe drug was used. Ambrisentan pharmacokinetics was assessed on days 1, 10 and 20, and midazolam pharmacokinetics before and on days 1, 10, 17 and 20. At steady state, ambrisentan exposure was similar in extensive and ultrarapid metabolizers but 43% larger in poor metabolizers (p < 0.01). In all volunteers, SJW reduced ambrisentan exposure and the relative change (17-26%) was similar in all genotype groups. The extent of this interaction did not correlate with the changes in CYP3A activity (midazolam clearance) (rs = 0.23, p = 0.34). Ambrisentan had no effect on midazolam pharmacokinetics. In conclusion, SJW significantly reduced exposure with ambrisentan irrespective of the CYP2C19 genotype. The extent of this interaction was small and thus likely without clinical relevance.

[Comparative pharmacokinetics of syringin, eleutheroside E and isofraxidin in rat plasma after intravenous administration of each monomer and Ciwujia injection].

To compare the pharmacokinetics of syringin, eleutheroside E and isofraxidin after intravenous administration of each monomer and Ciwujia injection. Twenty-four Sprague-Dawley rats were randomly divided into four groups and intravenously administrated with syringin, eleutheroside E, isofraxidin, and Ciwujia injection, respectively. The concentrations of the three components in rat plasma were determined by LC-MS/MS. DAS 2.0 software was applied to calculate the pharmacokinetic parameters while the SPSS 17.0 software was used for statistical analysis. Significant difference (P < 0.05) was found between each monomer and the injection on the main pharmacokinetic parameters such as AUC, CL and t1,/2. Compared with the injection, the group treated with the syringin has obvious decrease in AUC, and increase in CL while the group treated with eleutheroside E has obvious increase in AUC, and decrease in CL The t1/2 of isofraxidin was prolonged in Ciwujia injection. Pharmacokinetic characters of the ingredients in the injection varied greatly from the monomer. Other constituents in the injection may have an impact on the pharmacokinetic profiles of these three components.

Characterization of eleutheroside B metabolites derived from an extract of Acanthopanax senticosus Harms by high-resolution liquid chromatography/quadrupole time-of-flight mass spectrometry and automated data analysis.

We elucidated the structure and metabolite profile of eleutheroside B, a component derived from the extract of Acanthopanax senticosus Harms, after oral administration of the extract in rats. Samples of rat plasma were collected and analyzed by selective high-resolution liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF MS) automated data analysis method. A total of 11 metabolites were detected: four were identified, and three of those four are reported for the first time here. The three new plasma metabolites were identified on the basis of mass fragmentation patterns and literature reports. The major in vivo metabolic processes associated with eleutheroside B in A. senticosus include demethylation, acetylation, oxidation and glucuronidation after deglycosylation. A fairly comprehensive metabolic pathway was proposed for eleutheroside B. Our results provide a meaningful basis for drug discovery, design and clinical applications related to A. senticosus in traditional Chinese medicine.

Optimization, in vitro release and bioavailability of gamma-oryzanol-loaded calcium pectinate microparticles reinforced with chitosan.

Response surface methodology was used to optimize coating conditions, including chitosan concentration (X(1)) and coating time (X(2)), for sustained release of chitosan-coated Ca-pectinate (CP) microparticles containing oryzanol (OZ). The optimized values of X(1) and X(2) were found to be 1.48% and 69.92 min, respectively. These optimized values agreed favorably with the predicted results, indicating the utility of predictive models for the release of OZ in simulated intestinal fluid. In vitro release studies revealed that the chitosan-coated CP microparticles were quite stable under acidic conditions, but swell and disintegrate under alkaline conditions. In vivo release study of OZ, physically entrapped within chitosan-coated CP microcapsules, demonstrated the sustained release of OZ and could be used to improve the bioavailability of OZ following oral administration.

Simultaneous determination of harpagoside and cinnamic acid in rat plasma by high-performance liquid chromatography: application to a pharmacokinetic study.

Radix Scrophulariae (xuanshen) is one of the famous Chinese herbal medicines widely used to treat rheumatism, tussis, pharyngalgia, arthritis, constipation, and conjunctival congestion. Harpagoside and cinnamic acid are the main bioactive components of xuanshen. The purpose of this study was to develop an HPLC-UV method for simultaneous determination of harpagoside and cinnamic acid in rat plasma and investigate pharmacokinetic parameters of harpagoside and cinnamic acid after oral administration of xuanshen extract (760 mg kg(-1)). After addition of syringin as internal standard, the analytes were isolated from plasma by liquid-liquid extraction. Separation was achieved on a Kromasil C18 column, and detection was by UV absorption at 272 nm. The described assay was validated in terms of linearity, accuracy, precision, recovery, and limit of quantification according to the FDA validation guidelines. Calibration curves for both analytes were linear with the coefficient of variation (r) for both was greater than 0.999. Accuracy for harpagoside and cinnamic acid ranged from 100.7-103.5% and 96.9-102.9%, respectively, and precision for both analytes were less than 8.5%. The main pharmacokinetic parameters found for harpagoside and cinnamic acid after oral infusion of xuanshen extract were as follows: Cmax 1488.7 +/- 205.9 and 556.8 +/- 94.2 ng mL(-1), Tmax 2.09 +/- 0.31 and (1.48 +/- 0.14 h, AUC(0-24) 10,336.4 +/- 1426.8 and 3653.1 +/- 456.4 ng h mL(-1), AUC(0-infinity) 11,276.8 +/- 1321.4 and 3704.5 +/- 398.8 ng h mL(-1), and t(1/2) 4.9 +/- 1.3 and 2.5 +/- 0.9 h, respectively. These results indicated that the proposed method is simple, selective, and feasible for pharmacokinetic study of radix Scrophulariae extract in rats.

Determination and pharmacokinetic study of syringin and chlorogenic acid in rat plasma after administration of Aidi lyophilizer.

A high-performance liquid chromatographic (HPLC) method was developed for the first time to simultaneously quantify syringin and chlorogenic acid in rat plasma using wavelength-transfer technology. The analysis was performed on a Diamonsil C(18) column (200 x 4.6 mm i.d., 5 microm particle size) with isocratic mobile phase consisting of acetonitrile-0.05% phosphoric acid (12:88, v/v). The linear ranges were 0.20-10 and 0.25-30 microg/mL, respectively. The lower limits of quantification were 0.20 and 0.25 microg/mL, respectively. The method was shown to be reproducible and reliable with intraday precision below 8.5 and 6.1%, interday precision below 7.1 and 5.5%, accuracy within +/-7.1 and +/-8.6%, and mean extraction recovery excess of 92.1 and 80.9%, respectively, which were all calculated from the blank plasma sample spiked with syringin and chlorogenic acid at three concentrations of 0.20, 1.0 and 6.0 microg/mL for syringin and 0.25, 2.0 and 20 microg/mL for chlorogenic acid. This method was validated for specificity, accuracy and precision and was successfully applied to the pharmacokinetic study of syringin and chlorogenic acid in rat plasma after intravenous administration of Aidi lyophilizer.