Comparative pharmacokinetics of paclitaxel after oral administration of Taxus yunnanensis extract and pure paclitaxel to rats

Taxus yunnanensis (T. yunnanensis) is endemic to China and has been used in traditional medicine for the treatment of cancer, diabetic ailments and others. Paclitaxel is a representative antitumor compound in the Taxus species. The pharmacokinetic behavior of paclitaxel after oral administration of the crude extract of T. yunnanensis has not been investigated. This study attempts to compare the pharmacokinetics of paclitaxel after an oral administration of the crude extract of the twigs and leaves of T. yunnanensis and pure paclitaxel. A UPLC and a UPLC/MS/MS analysis method were developed for the determination of paclitaxel in T. yunnanensis extract and in the comparative pharmacokinetic study. Caco-2 cells were used to investigate the transport profile of paclitaxel in vitro. In the pharmacokinetic study, rats were randomly grouped and administered with T. yunnanensis extract or pure paclitaxel. The results showed that the AUC and C_max of paclitaxel in rats receiving the T. yunnanensis extract were significantly increased than those receiving the pure paclitaxel, and the in vitro Caco-2 cell monolayer transport study found that the coexisting constituents in the extract of T. yunnanensis could inhibit the efflux of paclitaxel. These findings suggested that the oral absorption and bioavailability of paclitaxel in T. yunnanensis extract were remarkably higher when compared with the pure paclitaxel, and the coexisting constituents in the T. yunnanensis extract might play an important role for the enhancement of the oral absorption and bioavailability of paclitaxel.     

Comparative pharmacokinetics of baicalin in normal and the type 2 diabetic rats after oral administration of the Radix scutellariae extract

Radix scutellariae was used alone or in combination with other medicinal herbs in the treatment of type 2 diabetes mellitus in China. At present, the pharmacokinetics of baicalin in type 2 diabetic rats following oral administration of Radix scutellariae extract was investigated. The results showed that the pharmacokinetics (especially AUC) of baicalin in type 2 diabetic rats after oral administration of Radix scutellariae extract was remarkably different from that in normal rats. Then the mechanism which resulted in the increased AUC of baicalin in diabetic rats was investigated from system clearance and presystemic metabolism. And it was found that the increased AUC of baicalin in diabetic rats at least partly resulted from higher production of baicalein in the intestinal tract of type 2 diabetic rats. Moreover, the activity of β-glucuronidase in intestinal mucosa of type 2 diabetic rats was demonstrated to be higher than that in normal rats, which confirmed the results above. In conclusion, the pharmacokinetic behavior of baicalin was significantly altered in type 2 diabetic rats after orally administrated Radix scutellariae extract, which may partly result from the increased activity of intestinal β-glucuronidase under the pathological state of type 2 diabetes mellitus.     

Pharmacokinetic study of baicalein after oral administration in monkeys

Baicalein, a flavonoid originally isolated from the root of Scutellaria baicalensis Georgi, has numerous pharmacological activities. Up to now, several studies regarding the pharmacokinetic profiles of baicalein have been described, while there is no such study reported in monkey, the species which is more similar to human. The purpose of this study was to investigate the pharmacokinetic profiles of baicalein after oral administration in monkeys. After orally administrating three doses of baicalein in monkeys, multi-peaks of the plasma concentration-time curves were observed and the non-linear pharmacokinetics for baicalein and its metabolite baicalin were found at doses of 50-500mg/kg. In order to calculate the absolute bioavailability, the intravenous pharmacokinetic study was also carried out after intravenous administration of 10mg/kg baicalein. The absolute bioavailability of baicalein in different doses was ranged from 13.1% to 23.0%. In this study, baicalein and baicalin were determined by LC-MS method. The chromatographic separation was performed on Agilent Poroshell 120 SB-C18 column (2.7μm, 2.1×50mm). Baicalein and baicalin were detected by single quadrupole mass spectrometer equipment with electrospray ionization interface with the selected ion monitoring mode. The assay was linear for both baicalein and baicalin with the correlation coefficients>0.99. The intra- and inter-day precisions for baicalein and baicalin were all less than 15% by relative standard deviation. The analytes were stable during samples storage and handling, and no matrix effects were observed. The method we developed in this study was sensitive, precise, stable and producible.     

Comparative pharmacokinetics of three triterpene acids in rat plasma after oral administration of Poria extract and its formulated herbal preparation: GuiZhi-FuLing capsule

A sensitive liquid chromatographic-mass spectrometric technique coupled with liquid-liquid extraction method was developed and validated for simultaneous determination of dehydro-tumulosic acid, tumulosic acid and polyporic acid C in rat plasma. The analytes were separated on a Kromasil C₁₈ column with a total running time of 12.5 min. Author had compared the pharmacokinetics of dehydro-tumulosic acid, tumulosic acid and polyporic acid C after oral administration of the extract of Poria and its formulated herbal preparation (GuiZhi-FuLing capsule). The improved pharmacokinetic profiles of the three compounds were found in the GuiZhi-FuLing capsule, indicating the more effective absorption and the slower elimination, compared with the Poria extract. Furthermore, this study revealed that as far as the Poria extract was concerned, it is very valuable to be used as a clinical instruction of GF capsule.     

Pharmacokinetics of brucine after intravenous and oral administration to rats

The toxicity depending on both dose and administration route is the major obstacle to the development of brucine, a bioactive alkaloid from Semen Strychni. In this study, the apparent partition coefficient and plasma protein binding extent of brucine were determined. In addition, the dose-dependency of the pharmacokinetics of brucine was investigated. Three intravenous (2.5, 5 and 10 mg/kg) and three oral (10, 20 and 40 mg/kg) doses were administered to rats. After intravenous administration, the systemic clearance was reduced and AUC was nonlinearly increased as a function of dose. Upon oral administration, brucine was rapidly absorbed (T_max < 0.5 h), which was consistent with previously reported high Caco-2 P_app values. The increase in AUC was proportional to the increase in dose. The oral bioavailability (F) did not vary with the dose (F = 40.31%, 47.15% and 43.02% for 10, 20, 40 mg/kg doses, respectively). However, the dose-proportionality was not observed with C_max. The values of C_max/Dose were calculated to be 92.92 ± 45.83, 55.73 ± 24.01 and 36.29 ± 22.44 μg/L for 10, 20 and 40 mg/kg, respectively. The results of dose-dependent pharmacokinetic behavior under different administration routes may account for the significantly different toxicities of brucine between intravenous and oral administration.     

The studies of anti-inflammatory and analgesic activities and pharmacokinetics of Oxytropis falcate Bunge extraction after transdermal administration in rats

The aim of this study was to evaluate the activities of anti-inflammatory and analgesic of the total flavonoids extraction from Oxytropis falcate Bunge (FEO) after transdermal administration. The pharmacokinetics and absolute bioavailability of FEO in rat, furthermore, was studied. Firstly, the anti-inflammatory and analgesic effects of the FEO were studied by xylene-induced ear edema, adjuvant-induced joint inflammation law in rats, acetic acid-induced writhing and hot-plate tests in mice. Secondly, we developed a sensitive and specific HPLC method to analyze 2′, 4′-dihydroxychalcone (TFC, the mainly ingredient of FEO) in rat plasma to study the pharmacokinetic of TEC. The results showed FEO has anti-inflammatory and analgesic property in a dose-dependent manner, and that the high dose group (90.6 mg/kg) of FEO appeared more significantly effective than the positive drug. From the pharmacokinetic studies of TFC in rats, we got the main pharmacokinetic parameters of TFC, providing a basis for the future studies in clinic.     

Comparative pharmacokinetics and bioavailability studies of quercetin, kaempferol and isorhamnetin after oral administration of Ginkgo biloba extracts, Ginkgo biloba extract phospholipid complexes and Ginkgo biloba extract solid dispersions in rats

The aim of this study was to improve the oral bioavailability of Ginkgo biloba extract (GBE) through preparing G. biloba extract phospholipid complexes (GBP) and G. biloba extract solid dispersions (GBS). Firstly we prepared the GBP and GBS and studied their physicochemical properties by differential scanning calorimetry (DSC), powder X-ray diffraction (XRD) and dissolution. Then we studied the pharmacokinetic characteristics and bioavailability in rats. The results showed that the bioavailability of quercetin, kaempferol and isorhamnetin in rats was increased remarkably after oral administration of GBP and GBS comparing with GBE. The bioavailabilities of GBP increased more than that of GBS.     

Pharmacokinetic study of luteolin,apigenin, chrysoeriol and diosmetin after oral administration of Flos Chrysanthemi extract in rats

Flos Chrysanthemi (the flower of Chrysanthemum morifolium Ramat.) is widely used in China as a food and traditional Chinese medicine for many diseases. Luteolin and apigenin are two main bioactive components in Flos Chrysanthemi, and chrysoeriol and diosmetin are two methylated metabolites of luteolin in vivo by cathechol-O-methyltransferase (COMT). However, there was lack of pharmacokinetic information of chrysoeriol and diosmetin after oral administration of Flos Chrysanthemi extract (FCE). The present study aimed to develop an HPLC-UV method for simultaneous determination of rat plasma concentration of luteolin, apigenin, chrysoeriol and diosmetin and utilize it in pharmacokinetic study of the four compounds after orally giving FCE to rats. The method was successfully validated and applied to the pharmacokinetic study when oral administration of FCE to rats with or without co-giving a COMT inhibitor, entacapone. Chrysoeriol and diosmetin were detected in rat plasma after oral administration of FCE and their concentrations were significantly decreased after co-giving entacapone. Furthermore, AUC of luteolin was significantly increased by entacapone, while that of chrysoeriol was decreased by entacapone, which revealed COMT might play an important role in the disposition of luteolin in rats after dosing of FCE. In conclusion, a sensitive, accurate and reproducible HPLC-UV method for simultaneous determination of luteolin, apigenin, chrysoeriol and diosmetin in rat plasma were developed, pharmacokinetics of chrysoeriol and diosmetin combined with luteolin and apigenin were characterized after oral administration of FCE to rats, which gave us more information on pharmacokinetics and potential pharmacological effects of FCE in vivo.     

Comparative pharmacokinetic study of paeoniflorin and albiflorin after oral administration of Radix Paeoniae Rubra in normal rats and the acute cholestasis hepatitis rats

A comparative study was designed and conducted to compare the pharmacokinetic difference of paeoniflorin and albiflorin after oral administration of Radix Paeoniae Rubra to normal rats and the acute cholestasis hepatitis rats induced by alpha-naphthylisothiocyanate (ANIT). UPLC-ESI-MS/MS method was employed to determine the level of paeoniflorin and albiflorin in rat plasma using geniposide as the internal standard (IS). Unpaired Student's t-test was used for the statistical comparison. The investigation showed that there were significant differences between the normal rats and the acute cholestasis hepatitis rat groups in calculated parameters, such as AUC(0-t), AUC(0-∞), T(max) and CLz/F. The results indicated that acute liver injury in rats could alter the pharmacokinetics of drug. Since patients are the final users of the drug, it is essential to investigate the pharmacokinetics of the drug in disease status. Therefore, we used normal rats and the acute cholestasis hepatitis rats to study pharmacokinetics of Radix Paeoniae Rubra with the purpose of examining the influence of disease on the metabolic course.     

Ultra-performance liquid-chromatography with tandem mass spectrometry performing pharmacokinetic and biodistribution studies of croomine,neotuberostemonine and tuberostemonine alkaloids absorbed in the rat plasma after oral administration of Stemonae Radix

Stemonae Radix (Stemona tuberosa Lour, Bai Bu) is an important traditional Chinese medicinal (TCM) plant known for its antitussive activity. Croomine, neotuberostemonine and tuberostemonine alkaloids of Stemonae Radix are major components responsible for antitussive action. In this work, plasma pharmacokinetic and biodistribution characteristics of the three alkaloids after oral administration of Stemonae Radix are investigated using a rapid and sensitive UPLC-Q-TOF–HDMS method. Mass spectrometry (MS) was performed on a Waters Micromass high-definition technology with an electrospray ionization source in positive ion mode, with excellent MS mass accuracy and enhanced MS data acquisition. Separation of main alkaloids was achieved on a Waters BEH C₁₈ column by linear gradient elution. Data were analyzed and estimated by compartmental methods and pharmacokinetic parameters calculated using WinNonlin Professional version 5.1. It was found that croomine, neotuberostemonine and tuberostemonine had faster absorbed into the bloodstream, maintain the high plasma concentration, and pose a large AUC value. The biodistribution of neotuberostemonine and tuberostemonine showed that the higher levels were in liver, and lung. Croomine was discovered in brain and showed that it could cross the blood–brain barrier, indicating that croomine plays an antitussive effect as acting on the central nervous system. Neotuberostemonine and tuberostemonine were not discovered in brain, demonstrating that they play an antitussive effect as peripheral antitussive. This work suggests that the pharmacokinetics and biodistribution based-UPLC-Q-TOF–HDMS can provide a reliable tools for screening bioactive components contributing to pharmacological effects of medicinal herbs.     

Pharmacokinetics of puerarin in pregnant rats at different stages of gestation after oral administration

This study aims to observe the effects of gestational stage on the pharmacokinetics of puerarin after oral administration in rats. The pharmacokinetics of puerarin was studied in pregnant rats using a sensitive and reproducible high-performance liquid chromatography/ultraviolet method. The concentration–time curves in both normal and pregnant rats were fit into a two-compartment model. The results indicated that gestation influences the pharmacokinetics of puerarin at different levels, especially during the early stages of pregnancy. Furthermore, puerarin penetrates the placental barrier and maintains high concentrations in fetal rat plasma. Therefore, puerarin administration should be carefully considered in pregnant women.     

Comparative pharmacokinetic and bioavailability studies of three salvianolic acids after the administration of Salviae miltiorrhizae alone or with synthetical borneol in rats

Salviae miltiorrhizae is one of the most commonly used herbal plants in the treatment of numerous ailments including cardiovascular diseases for hundreds of years. According to the theory of traditional Chinese herbal medicine, S. miltiorrhizae is always used in combination with borneol to obtain better pharmacological effects. The purpose of this study was to investigate the effects of borneol on the pharmacokinetic and bioavailability of S. miltiorrhizae. The pharmacokinetics studying on rosmarinic acid, salvianolic acid A and salvianolic acid B which are the main active compounds of S. miltiorrhizae in rat plasma, was achieved using a optimal high-performance liquid chromatographic technique coupled with liquid-liquid extraction method. After administration of either single salvianolic acids or salvianolic acids in combination with borneol, plasma concentrations of rosmarinic acid, salvianolic acid A and salvianolic acid B of male Sprague-Dawley rats were determined at different time points (5, 10, 20, 30, 45, 60, 90, 120, 180, 240, 300, and 360 min). In comparison with salvianolic acid extract alone, there were statistically significant differences in pharmacokinetic parameters of rosmarinic acid, salvianolic acid B and salvianolic acid A, and the bioavailability of the three salvianolic acids increased by different degrees when the salvianolic acid extract and borneol were administered together. These results indicated that borneol could enhance the intestinal absorption, decrease the distribution and inhibit the metabolism of salvianolic acids.     

Comparative effect of oral administration and topical application of alcoholic extract of Terminalia arjuna bark on incision and excision wounds in rats

The effects of 50% ethanolic extract of the bark Terminalia arjuna and tannins isolated from the bark were studied for wound healing activity in incision and excision wound models, after oral or topical application in form of a hydrogel. The findings revealed a statistically significant increase in the tensile strength of the incision wounds and increase in the percent reduction in wound size of excision wounds as compared to control. However, the topical treatment with tannins was found to be superior in both incision and excision wound studies. The estimated increase in hydroxyproline content of the granulation tissue of the excision wounds indicated rapid collagen turnover thus, leading to rapid healing of the wounds.     

Pharmacokinetic properties of isorhamnetin, kaempferol and quercetin after oral gavage of total flavones of Hippophae rhamnoides L. in rats using a UPLC-MS method

An ultra performance liquid chromatography-mass spectrometric (UPLC-MS) method was developed to investigate the pharmacokinetic properties of isorhamnetin, kaempferol and quercetin from a total flavone extract of Hippophae rhamnoides L. (TFH) after single dose oral administration. Rat plasma samples were pretreated using liquid-liquid extraction, and chromatographic separation was performed on a C₁₈ column using a linear gradient of methanol and formic acid (0.1%). The pharmacokinetic parameters of isorhamnetin, kaempferol and quercetin from TFH in rats were quantitatively determined by UPLC with photodiode array detection (PDA). The qualitative detection of the three flavones was accomplished by selected ion monitoring in negative ion mode ESI-MS. Results of the pharmacokinetic study indicate that the three flavones in TFH were absorbed by passive diffusion in rats, and no “double-peak” phenomenon was observed in C-t curves of the three flavones from TFH except for quercetin. Results of this study indicate that the pharmacokinetic behaviors of isorhamnetin, kaempferol and quercetin when administered together in a complex herbal extract might be different than the individual behaviors of the same compounds administered in their pure forms. Results of this study also demonstrate that UPLC-MS is a rapid and practical method to determine the pharmacokinetic parameters of flavones present in an herbal extract.     

Pharmacokinetics and tissue distribution of schizonepetin in rats

Schizonepetin, a natural monoterpene from Herba Schizonepetae, is a potential antiviral agent. In this paper, a simple, rapid and sensitive HPLC-UV method was first developed and validated for the determination of schizonepetin in rat plasma and tissue homogenates after oral and intravenous administration. The results showed that schizonepetin was absorbed and eliminated rapidly, and its oral absolute bioavailability in rats achieved about 75%. The drug distributed widely in various tissues of rats, and had no long-term accumulation in vivo. The research provides reliable scientific data for designing drug treatment regimens of schizonepetin.     

Determination of oxymatrine and its active metabolite matrine in human plasma after administration of oxymatrine oral solution by high-performance liquid chromatography coupled with mass spectrometry

A rapid, sensitive and selective high-performance liquid chromatography mass spectrometric method has been developed and validated for the simultaneous determination of oxymatrine and its active metabolite matrine in human plasma after administration of oxymatrine oral solution. Analytes were extracted from the plasma by liquid-liquid extraction with chloroform. The chromatographic separation was accomplished on a Venusil C₁₈ column (150 mm × 4.6 mm, 5 μm) protected by a C₁₈ guard column (4.0 mm × 2.0 nm; Phenomenex, Torrance, CA, USA). Analytes were detected on a single quadruple mass spectrometer by selected ion monitoring mode via electrospray ionization source. The assay had a lower limit of quantification of 1.5 ng · mL^− 1 for oxymatrine and 3 ng·mL^− 1 for matrine in plasma. The calibration curves were linear in the measured range. The overall precision and accuracy for all concentrations of quality controls and standards were within ± 15%. The proposed method enabled unambiguous identification and quantification of oxymatrine and its active metabolite matrine in vivo. The results provided a meaningful basis for evaluating the clinical applications of the oxymatrine oral solution.     

Permeability determination and pharmacokinetic study of nobiletin in rat plasma and brain by validated high-performance liquid chromatography method

In the present study, we are reporting permeability and pharmacokinetics of nobiletin in rat plasma and brain, using a validated reverse phase high performance liquid chromatographic method. Protein precipitation method was used for the extraction of nobiletin and coumarin (IS) from rat plasma and brain tissue. The system was run in isocratic mode with mobile phase consisting of potassium dihydrogen ortho-phosphate (pH 4.5; 0.04 mM) and acetonitrile in ratio of 50:50, v/v. The total chromatographic run time was 9.0 min. The method was proved to be accurate and precise at linearity range of 0.05–10 μg/mL with a correlation coefficient (r) of ≥ 0.994 in rat plasma and ≥ 0.995 in rat brain. The intra- and inter-day precision and accuracy values are found to be within the assay variability limits as per the FDA guidelines. Nobiletin was found stable in the battery of stability studies viz., bench-top, auto-sampler, freeze/thaw cycles and long term storage in a freezer at − 70 ± 10 °C. Maximum concentrations of nobiletin in both plasma and brain were observed at 1 h after single oral dosing (50 mg/kg). The maximum concentration in plasma and brain were 1.78 and 4.20 μg/mL, respectively. The AUC_0–t in plasma and brain were 7.49 and 20.66 μg·h/mL, respectively. The mean elimination half life (t_1/2) in plasma and brain were 1.80 and 11.42 h, respectively. The Parallel Artificial Membrane Permeability Assay (PAMPA) permeability of nobiletin was found to be high at both pH 4.0 and 7.0.     

Pharmacokinetics and tissue distribution study of scoparone in rats by ultraperformance liquid-chromatography with tandem high-definition mass spectrometry

Scoparone is an important constituent of Yinchenhao (Artemisia annua L.), a famous Chinese medicinal plant, and has several known bioactivities, and displayed bright prospects in prevention and therapy of jaundice and liver disorders. The aim of this study was to investigate the in vivo plasma pharmacokinetic and tissue distribution characteristics of scoparone after oral administration. The levels of scoparone in plasma, and tissues were measured by a rapid and sensitive UPLC-MS/MS method. The biosamples were prepared using methanolic precipitation and the separation of scoparone was achieved on a UPLC HSS T3 column by linear gradient elution using water (containing 0.1% formicacid) and acetonitrile (containing 0.1% formic acid) as the mobile phase at a flow rate of 0.5mL/min The total run time was only 3.9min. Our results successfully demonstrate that this method has excellent and satisfactory selectivity, sensitivity, linearity, precision, accuracy and recovery. The estimated pharmacokinetic parameters (i.e., C(max), AUC and CL), were C(max)=14.67mg/L, AUC=81.15mg*h/L, CL=1.23L/h for scoparone. The pharmacokinetic study found that scoparone was distributed and eliminated rapidly in rats. Tissue distribution showed the highest level was observed in liver, followed by the kidney and spleen; the lower level appeared in the muscle, thyroid, and adrenal. It was not detected in the brain which indicated that scoparone does not cross the blood-brain barrier after oral administration. Our developed method was suitable for the study on pharmacokinetics and tissue distribution of scoparone after oral administration.