A rapid method for simultaneous quantification of berberine, berbamine, magnoflorine and berberrubine in mouse serum using UPLC-MS/MS.

Berberidis cortex, the dry bark of Berberis L., is used to treat diabetes and contains at least three bioactive components: berberine (BBR), berbamine (BBM) and magnoflorine (MGF). BBR in turn is metabolized into berberrubine (BRB). Although it is possible to quantify each of these components individually in serum, there are currently no methods for simultaneously quantifying all four. Here, we developed a specific and rapid method for simultaneously quantifying BBR, BBM, MGF and BRB in mouse serum using ultra high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Samples were pretreated by protein precipitation, separated using an ACQUITY UPLC® BEH C18 column and detected by a triple quadrupole mass spectrometer with electrospray ionization. The compound [9,10-(OC2H3)2]-BBR (d6-BBR) was used as internal standard for BBR and BRB, boldine (BOL) for MGF and tetrandrine (TET) for BBM. The m/z transitions for precursor/product ion pairs were 336.1/320.2 for BBR, 305.2/566.3 for BBM, 342.0/297.1 for MGF, 322.1/307.2 for BRB, 342.2/294.3 for d6-BBR, 312.2/580.3 for TET and 328.1/265.2 for BOL. We validated our method in terms of selectivity, linearity and lower limit of quantification, accuracy, precision, matrix effect and recovery, dilution integrity and stability. This method showed good linearity from 0.1 to 40 ng/mL for BBR, 8 to 3200 ng/mL for BBM, 5 to 2000 ng/mL for MGF and 0.2 to 80 ng/mL for BRB. The chromatographic run time was 3.9 min, and sample preparation took approximately 15 min per batch. Finally, we used our method to measure BBR, BBM, MGF and BRB in serum from diabetic mice after gavage administration of BBR hydrochloride, BBM hydrochloride, and MGF. This method is precise, accurate and suitable for high-throughput sample analysis.

Pharmacokinetics of 10-hydroxycamptothecin-tetrandrine liposome complexes in rat by a simple and sensitive ultra-high performance liquid chromatography with tandem mass spectrometry.

10-Hydroxycamptothecin is a drug to cure various cancers. However, the 10-hydroxycamptothecin cannot be widely applied in clinics due to fast elimination and resistance of various cancers to the drug. Nevertheless, co-treatment with tetrandine is known to reverse the resistance of multi-drug resistant cancers, and may present an effective strategy to improve the efficacy of 10-hydroxycamptothecin. In order to improve the bioavailability and prolong the treatment time of the 10-hydroxycamptothecin in vivo, we prepared 10-hydroxycamptothecin-tetrandrine liposome complexes with 10-hydroxycamptothecin as the basic anticancer drug, tetrandrine and liposomes as carriers. In this article, an ultra-high performance liquid chromatography tandem mass spectrometry method for the analysis of 10-hydroxycamptothecin and tetrandrine in plasma has been developed, validated, and utilized to compare the pharmacokinetics of both drugs in the original dosage form and administered as liposome complexes. According to the pharmacokinetic parameters of mean residence time, half-life period and clearance rate, the 10-hydroxycamptothecin-tetrandrine liposome complexes prolongs the retention and circulation time of 10-hydroxycamptothecin in vivo, achieving a good sustained release effect. To the best of our current knowledge, the pharmacokinetic properties of 10-hydroxycamptothecin-tetrandrine liposome complexes in rats have not been reported yet. Our study can provide a helpful reference for further related study.

An UPLC-MS/MS method for quantifying tetrandrine and its metabolite berbamine in human blood: Application to a human pharmacokinetic study.

Tetrandrine (TET) was approved by the China Food and Drug Administration (CFDA) for the treatment of silicosis. However, patients can't use this effective drug chronically due to side effects such as hypersomnia, asthenia, etc. The purpose of this study is to develop an UPLC-MS/MS method to quantify TET and its major metabolite and apply the method in a single dose human pharmacokinetic study. A Restek UItra BiPh column (100×2.1mm, 5µm) was used with acetonitrile and 0.1% formic acid in water as the mobile phases. The mass analysis was performed in a Waters Xevo TQ mass spectrometer via multiple reaction monitoring (MRM) with positive scan mode. A one-step protein precipitation by acetonitrile was used to extract the analytes from blood sample. The method showed linearity in the concentration ranges of 2.05-1050.00ng/mL for TET and 1.27-650.00ng/mL for berbamine. The intra/inter-day precisions were less 15% for these two analytes. The extraction recoveries of these two analytes were from 75.6% to 107.8% and the matrix effects ranged from 92.4% to 110.4%. The stabilities of these compounds in plasma were evaluated by analyzing three different concentrations following storage at 25°C for 6h, and -80°C for 30days. All the samples displayed less than 15.0% variations. The validated method was applied to PK study in human and the PK parameters of TET and berbamine were determined. In conclusion, a robust and sensitive LC-MS/MS method was developed and validated. In addition, the results of human PK experiment showed that TET and berbamine could be accumulated and more study is needed to establish a reasonable dose segment.

Determination of cepharanthine in rat plasma by LC-MS/MS and its application to a pharmacokinetic study.

CONTEXT: Cepharanthine (CPA) has been reported to possess a wide range of pharmacological activities. OBJECTIVE: This study investigates the pharmacokinetic characteristics after oral or intravenous administration of CPA by using a sensitive and rapid LC-MS/MS method. MATERIALS AND METHODS: A sensitive and rapid LC-MS/MS method was developed for the determination of CPA in Sprague-Dawley rat plasma. Twelve rats were equally randomized into two groups, including the intravenous group (1 mg/kg) and the oral group (10 mg/kg). Blood samples (250 µL) were collected at designated time points and determined using this method. The pharmacokinetic parameters were calculated. RESULTS: The calibration curve was linear within the range of 0.1-200 ng/mL (r = 0.999) with the lower limit of quantification at 0.1 ng/mL. After 1 mg/kg intravenous injection, the concentration of CPA reached a maximum of 153.17 ± 16.18 ng/mL and the t1/2 was 6.76 ± 1.21 h. After oral administration of 10 mg/kg of CPA, CPA was not readily absorbed and reached Cmax 46.89 ± 5.25 ng/mL at approximately 2.67 h. The t1/2 was 11.02 ± 1.32 h. The absolute bioavailability of CPA by oral route was 5.65 ± 0.35%, and the bioavailability was poor. DISCUSSION AND CONCLUSIONS: The results indicate that the bioavailability of CPA was poor in rats, and further research should be conducted to investigate the reason for its poor bioavailability and address this problem.

Determination of a novel anticancer AMPK activator hernandezine in rat plasma and tissues with a validated UHPLC-MS/MS method: Application to pharmacokinetics and tissue distribution study.

Hernandezine, a novel anticancer AMPK activator, is a major active constituent of Thalictrum Ranunculaceae. A simple, specific and sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the quantification of hernandezine in rat plasma and tissues after intravenous administration. Sample preparation was carried out through a protein-precipitation extraction with acetonitrile using tetrandrine as internal standard (IS). The chromatographic separation was achieved by using an Agilent ZORBAX Eclipse Plus C18 column with a mobile phase of acetonitrile and water (containing 10mM ammonium acetate) in an isocratic elution way. The mass spectrometry (MS) analysis was conducted in positive ionization mode with multiple reaction monitoring (MRM) transitions at m/z 653.4→411.2 for hernandezine and m/z 623.3→381.3 for tetrandrine (IS). Calibration curves were linear over the ranges of 20.0-4000ng/ml f or both plasma samples and tissue samples (r>0.991). The lower limit of quantification (LLOQ) was 20.0ng/ml. The intra-day and inter-day precision (RSD%) were less than 14.0%, while the accuracy was ranged from 85.2% to 114.9%. Finally, this developed method was successfully applied in the pharmacokinetics and tissue distribution study of hernandezine after intravenous administration.

Pharmacokinetics of a multicomponent herbal preparation in healthy Chinese and African volunteers.

K-601 is an herbal formulation for influenza consisting of Lonicera japonica, Isatis indigotica, Rheum palmatum, Phellodendron chinense, and Scutellaria baicalensis. In this work, we characterized the chemical constituents in K-601, identified the absorbed compounds and determined their pharmacokinetics in 6 Chinese and African volunteers by liquid chromatography with time-of-flight mass spectrometry. Similarity evaluation for chromatographic fingerprint of nine different batches showed values above 0.983. Totally, 50 components were identified in K-601. Then, 15 major prototype compounds and 17 metabolites were identified in human plasma. Major metabolic pathways included glucuronidation, sulfation, methylation, demethylation, and reduction. The pharmacokinetics of the most abundant prototype compounds, berberine, jatrorrhizine, palmatine and magnoflorine were determined. Significant pharmacokinetic differences were observed between the African and Chinese subjects. The AUCs of the African is about 4-10 fold higher than that of the Chinese for the three benzylisoquinoline alkaloids. Magnoflorine, an aporphine alkaloid, was absorbed better in the Chinese than in the African. The biotransformation of K-601 by human intestinal microflora was also investigated. The major reactions included hydroxylation, methylation, demethylation, acetylation and reduction. Glucuronidation and sulfation were not observed with fecal flora. These results may be important and useful in linking data from pharmacological assays and clinical effects.

Development and validation of an on-line multidimensional SPE-LC-MS/MS method for the quantitation of Tetrandrine in blood samples.

On-line solid-phase extraction (SPE) is becoming an increasingly widespread technique in the clean-up of complex matrices such as body fluids, prior to chromatographic analysis. The use of small SPE columns instead of disposable SPE cartridges allows multiple injections and complete automation. In addition, it decreases the cost of consumables and improves the quality of the overall analysis. Coupling of SPE with HPLC combines sample preparation and separation in one system. In this paper a validated on-line multidimensional (MD) SPE-LC-MS/MS method is described for the determination of Tetrandrine (model drug) in human blood samples. The developed method showed the applicability of direct injection of plasma samples to an on-line MD-SPE-LC-MS/MS system to determine small molecules i.e. drugs. The experimental design is unique. Quantification was through tandem mass spectrometry with positive electrospray ionization (ESI) and multiple reactions monitoring (MRM). The limit of detection was calculated as 31.98 ng/mL. The linear range of the method was between 40.0 and 800.0 ng/mL. Pharmacokinetic parameters are usually determined by analysis of drug concentrations in plasma rather than whole blood. Parameters determined using plasma data may be misleading if concentrations of drug differ between plasma and red blood cells. We successfully applied the developed method for the determination of the distribution coefficient of the model drug Tetrandrine between human red blood cells and blood plasma proteins. The determination of distribution coefficient study results demonstrated that the developed method can provide direct and accurate measurement of RBC partitioning in a model drug and could be applied for screening of other compounds for potential high RBC partition, predicting potential drug toxicity and investigating mechanisms associated with RBC partitions.

Simultaneous determination of liensinine, isoliensinine and neferine in rat plasma by UPLC-MS/MS and application of the technique to pharmacokinetic studies.

ETHNOPHARMACOLOGICAL RELEVANCE: The in vivo effects of traditional herbal medicines are generally mediated by multiple bioactive components. The main constituents of Lotus Plumule are alkaloids such as liensinine, isoliensinine and neferine. In this study, a simple, sensitive, and robust analytical method based on ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) has been developed for the determination of the three alkaloids in rat plasma using carbamazepine as internal standard (IS). MATERIALS AND METHODS: After precipitation of the proteins with acetonitrile, chromatography was performed on an Acquity UPLC BEH C18 column (2.1mm×50mm, 1.7µm particle size) using a gradient elution with 0.1% formic acid in water and acetonitrile. Mass spectrometry involved positive electrospray ionization and multiple reaction monitoring (MRM) of the transitions at m/z 611.7→206.2 for liensinine, 611.3→192.2 for isoliensinine, 625.2→206.1 for neferine and m/z 237.1→194.2 for IS. RESULTS: The method was linear over the concentration range 5-1000ng/mL with a lower limit of quantifof 5ng/mL for each alkaloid. Inter- and intra-day precision (RSD%) were all within 11.4% and the accuracy (RE%) were equal or lower than 10.4%. Recoveries were more than 75.3% and matrix effects were not significant. Stability studies showed that the three alkaloids were stable under a variety of storage conditions. CONCLUSION: The method was successfully applied to a pharmacokinetic study involving intravenous administration of liensinine, isoliensinine and neferine to rats.

Ultra high performance liquid chromatography with tandem mass spectrometry method for the determination of tetrandrine and fangchinoline in rat plasma after oral administration of Fangji Huangqi Tang and Stephania tetrandra S. Moore extracts.

A rapid, sensitive, and reliable analytical method based on ultra high performance liquid chromatography with tandem mass spectrometry has been developed for the simultaneous determination of fangchinoline and tetrandrine in rat plasma. Plasma samples were pretreated by protein precipitation with acetonitrile. The analysis was performed on a C18 reversed-phase ultra high performance liquid chromatography column (2.1 mm × 100 mm, 3.5 µm, Agilent), and the flow rate was set at 0.4 mL/min. Under the experimental conditions, extraction recoveries from plasma were 68.1-72.8% for fangchinoline and 69.2-76.5% for tetrandrine. The plasma concentrations of tetrandrine and fangchinoline in rats at assigned time points were all successfully detected through exactly validated method. Good linearities were obtained in the range of 0.92-184 ng/mL for tetrandrine and in the range of 0.83-166 ng/mL for fangchinoline. The intra- and interday precisions for both analytes were within 11.1% and the accuracies were within the range of -10.7 to 11.3%. The developed method was then successfully applied to investigate the pharmacokinetic properties of these two alkaloids after oral administration of Stephania tetrandra S. Moore extracts and Fangji Huangqi Tang. The comparative results provided a meaningful basis for a better understanding of the practical value of the compatibility theory of traditional Chinese medicine in the clinic.

Screening and identification of multiple constituents and their metabolites of Fangji Huangqi Tang in rats by ultra-high performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry basing on coupling data processing techniques.

Fangji Huangqi Tang (FHT) is a classical formula widely used in Chinese clinical application. In this paper, a novel and advanced strategy has been developed for the multiple constituent identification of FHT in rats, which was basing on an ultra-high performance liquid chromatography equipped with electrospray ionization quadrupole time-of-flight mass spectrometry (UHPLC-ESI-Q-TOF-MS) method combined with dynamic background subtract (DBS) data acquisition and enhance peak list (EPL) data processing techniques. Firstly, a total of 58 potential bioactive compounds including alkaloids, flavonoids, saponins, saccharides and terpenoids were detected from FHT. Their chemical structures were identified by comparing the retention time and mass spectrometry data, as well as retrieving the reference literatures. Based on the same instrumental conditions, 33 compounds were found in rat serum after oral administration of FHT. After a considerate comparison with the former chemical identification results of FHT, 33 compounds were found, which turned out to be 8 original compounds of FHT as well as 25 metabolites, including 20 phase I and 5 phase II metabolites. The results indicated that the metabolic reactions included hydroxylation, hydrogenation, demethylation, tarine conjugation and acetylation. This study firstly reported the metabolism description of fangchinoline and tetrandrine in vivo, which could be very useful for further pharmacological and clinical studies of FHT. Meanwhile, it provided a practical strategy for rapid screening and identifying of multiple constituents and their metabolites of complex traditional Chinese medicine in biological matrix.

Hydrastine pharmacokinetics and metabolism after a single oral dose of goldenseal (Hydrastis canadensis) to humans.

The disposition and metabolism of hydrastine was investigated in 11 healthy subjects following an oral dose of 2.7 g of goldenseal supplement containing 78 mg of hydrastine. Serial blood samples were collected for 48 hours, and urine was collected for 24 hours. Hydrastine serum and urine concentrations were determined by Liquid Chromatography-tandem mass spectrometry (LC-MS/MS). Pharmacokinetic parameters for hydrastine were calculated using noncompartmental methods. The maximal serum concentration (Cmax) was 225 ± 100 ng/ml, Tmax was 1.5 ± 0.3 hours, and area under the curve was 6.4 ± 4.1 ng ⋅ h/ml ⋅ kg. The elimination half-life was 4.8 ± 1.4 hours. Metabolites of hydrastine were identified in serum and urine by using liquid chromatography coupled to high-resolution mass spectrometry. Hydrastine metabolites were identified by various mass spectrometric techniques, such as accurate mass measurement, neutral loss scanning, and product ion scanning using Quadrupole-Time of Flight (Q-ToF) and triple quadrupole instruments. The identity of phase II metabolites was further confirmed by hydrolysis of glucuronide and sulfate conjugates using bovine ß-glucuronidase and a Helix pomatia sulfatase/glucuronidase enzyme preparation. Hydrastine was found to undergo rapid and extensive phase I and phase II metabolism. Reduction, O-demethylation, N-demethylation, hydroxylation, aromatization, lactone hydrolysis, and dehydrogenation of the alcohol group formed by lactone hydrolysis to the ketone group were observed during phase I biotransformation of hydrastine. Phase II metabolites were primarily glucuronide and sulfate conjugates. Hydrastine undergoes extensive biotransformation, and some metabolites may have pharmacological activity. Further study is needed in this area.

An ex vivo approach to botanical-drug interactions: a proof of concept study.

ETHNOPHARMACOLOGICAL RELEVANCE: Botanical medicines are frequently used in combination with therapeutic drugs, imposing a risk for harmful botanical-drug interactions (BDIs). Among the existing BDI evaluation methods, clinical studies are the most desirable, but due to their expense and protracted time-line for completion, conventional in vitro methodologies remain the most frequently used BDI assessment tools. However, many predictions generated from in vitro studies are inconsistent with clinical findings. Accordingly, the present study aimed to develop a novel ex vivo approach for BDI assessment and expand the safety evaluation methodology in applied ethnopharmacological research. MATERIALS AND METHODS: This approach differs from conventional in vitro methods in that rather than botanical extracts or individual phytochemicals being prepared in artificial buffers, human plasma/serum collected from a limited number of subjects administered botanical supplements was utilized to assess BDIs. To validate the methodology, human plasma/serum samples collected from healthy subjects administered either milk thistle or goldenseal extracts were utilized in incubation studies to determine their potential inhibitory effects on CYP2C9 and CYP3A4/5, respectively. Silybin A and B, two principal milk thistle phytochemicals, and hydrastine and berberine, the purported active constituents in goldenseal, were evaluated in both phosphate buffer and human plasma based in vitro incubation systems. RESULTS: Ex vivo study results were consistent with formal clinical study findings for the effect of milk thistle on the disposition of tolbutamide, a CYP2C9 substrate, and for goldenseal׳s influence on the pharmacokinetics of midazolam, a widely accepted CYP3A4/5 substrate. Compared to conventional in vitro BDI methodologies of assessment, the introduction of human plasma into the in vitro study model changed the observed inhibitory effect of silybin A, silybin B and hydrastine and berberine on CYP2C9 and CYP3A4/5, respectively, results which more closely mirrored those generated in clinical study. CONCLUSIONS: Data from conventional buffer-based in vitro studies were less predictive than the ex vivo assessments. Thus, this novel ex vivo approach may be more effective at predicting clinically relevant BDIs than conventional in vitro methods.

Preparation and characterization of tetrandrine-phospholipid complex loaded lipid nanocapsules as potential oral carriers.

BACKGROUND: Tetrandrine is an active constituent that is extracted from the root tuber of the Chinese herb Stephania tetrandra S. Moore. It has shown various pharmacological effects, such as antitumor activity, multidrug resistance reversal, and hepatic fibrosis resistance. In clinical applications, it has been used to treat hypertension, pneumosilicosis, and lung cancer. However, the poor water solubility of tetrandrine has limited its application. In this study, a newly emerging oral drug carrier of phospholipid complex loaded lipid nanocapsules was developed to improve the oral bioavailability of tetrandrine. METHODS: The phospholipid complex was prepared with the solvent-evaporation method to enhance the liposolubility of tetrandrine. The formation of the phospholipid complex was confirmed with a solubility study, infrared spectroscopy, and a differential scanning calorimetry (DSC) analysis. The tetrandrine-phospholipid complex loaded lipid nanocapsules (TPC-LNCs) were prepared using the phase inversion method. Lyophilization was performed with mannitol (10%) as a cryoprotectant. TPC-LNCs were characterized according to their particle size, zeta potential, encapsulation efficiency, morphology by transmission electron microscopy, and crystallinity by DSC. In addition, the in vitro release of tetrandrine from TPC-LNCs was examined to potentially illustrate the in vivo release behavior. The in vivo bioavailability of TPC-LNCs was studied and compared to tetrandrine tablets in rats. RESULTS: The liposolubility of tetrandrine in n-octanol improved from 8.34 µg/mL to 35.64 µg/mL in the tetrandrine-phospholipid complex. The prepared TPC-LNCs were spherical-shaped particles with a small size of 40 nm and a high encapsulation efficiency of 93.9%. DSC measurements revealed that the crystalline state was less ordered in lipid nanocapsules. The in vitro release study demonstrated a fast release of approximately 25% in the first 1 hour, which was followed by a sustained release of 70% over 12 hours. The relative bioavailability of TPC-LNCs compared to that of tablets was 208%, indicating a significant improvement in the oral absorption of tetrandrine. CONCLUSION: The TPC-LNCs system developed in this study is a promising carrier that improves the oral bioavailability of tetrandrine in rats. The phospholipid complex loaded lipid nanocapsules have great potential for use as an oral drug delivery system for moderately lipophilic drugs that are encapsulated in the lipid nanocapsules.

Enhanced topical delivery of tetrandrine by ethosomes for treatment of arthritis.

The purpose of this work was to explore the feasibility of ethosomes for improving the antiarthritic efficacy of tetrandrine by topical application. It was found that tetrandrine was a weak base (pK(a) = 7.06) with pH-dependent partition coefficient. The spherical-shaped ethosomes were prepared by pH gradient loading method. Ex vivo permeation and deposition behavior demonstrated that the drug flux across rat skin and deposition of the drug in rat skin for ethosomes was 2.1- and 1.7-fold higher than that of liposomes, respectively. Confocal laser scanning microscopy confirmed that ethosomes could enhance the topical delivery of the drug in terms of depth and quantity compared with liposomes. The ethosomes were shown to generate substantial enhancement of therapeutic efficacy of tetrandrine on Freund's complete adjuvant-induced arthritis with regard to liposomes. These results indicated that ethosomes would be a promising carrier for topical delivery of tetrandrine into and across the skin.

A rapid and sensitive LC-MS/MS assay for the determination of berbamine in rat plasma with application to preclinical pharmacokinetic study.

Berbamine (BBM), a natural compound from Chinese herb Berberis amurensis, has recently received a great deal of attention due to its anti-leukemia activity. In this study, a rapid and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of BBM in rat plasma was developed for the first time. Caffeine was used as an internal standard. Chromatographic separation was performed on an ODS column with gradient elution using methanol-1% formic acid as mobile phase at a flow rate of 0.3mL/min. Quantification was through tandem mass spectrometry with positive electrospray ionization (ESI) and multiple reaction monitoring (MRM) at m/z 305.2→566.3 and 195.1→138.0 for BBM and IS, respectively. The lower limit of quantification was 1ng/mL with a linear range of 1-1000ng/mL. The intra- and inter-day assay precision (RSD) ranged from 2.0-6.4% to 2.5-5.5%, respectively, and the intra- and inter-day assay accuracy (RE) was between -5.8-6.0% and -6.5-1.4%, respectively. The validated method was successfully applied to the preclinical pharmacokinetic studies of BBM in rats. The elimination half-lives (t1/2) were (472.4±66.1), (509.6±97.0) and (486.2±94.6) min after single intravenous administration of 2, 4 and 8mg/kg BBM, respectively. The area under the plasma concentration versus time curve (AUC0-24h) and initial plasma concentration (C0) were linearly related to dose.

Effects of neferine on the pharmacokinetics of amiodarone in rats.

Amiodarone, an iodinated benzofuran derivative with predominantly class III anti-arrhythmic effects, is used to treat supraventricular and ventricular arrhythmias. The purpose of this study was to assess the potential of neferine, an effective anti-pulmonary fibrosis drug isolated from the embryo of Nelumbo nucifera Gaertner's seeds, to alter the pharmacokinetic profile of amiodarone. Experimental Sprague-Dawley rats were randomly divided into two groups. In groups 1 and 2, amiodarone was given to rats by intragastric and intravenous administration, respectively, while neferine was co-administratered by intragastric administration. Blood samples were collected from the orbital venous plexus at indicated time points and were analyzed for amiodarone concentration using RP-HPLC. The geometric mean ratio for C(max) and AUC(0-96) was calculated. There were no significant differences between the pharmacokinetics parameters of amiodarone administered intravenously or intragastrically and the control (without neferine) group (with ratios of 0.7-1.4 in all experimental groups), suggesting that neferine had no effect on amiodarone plasma pharmacokinetics. The dosage regimen of amiodarone does not need to be taken into consideration when combined with neferine.

The pharmacokinetical study of plant alkaloid tetrandrine with a simple HPLC method in rabbits.

A simple HPLC method was developed to quantify rabbit plasma tetrandrine (Tet) with propranolol (Pro) as internal standard. Based on the established method Tet and Pro were eluted at 7.1 and 12.0 min, respectively. It was shown that the concentration-time data of Tet fit the classical two-compartment model, no matter the drug was administered intravenously or orally to rabbits. The values of AUC(0 → ∞), clearance (Cl(0 → ∞)), volume of distribution (Vd), and elimination half-life (t(1/2ß)) of Tet were 59861.149 ± 26962.196 µg/L⁎min, 0.503 ± 0.173 L/min/kg, 179 ± 76.185 L/kg, and 283.808 ± 162.937 min for intravenous injection of 5mg/kg, or 18986.217 ± 7462.308 µg/L⁎min, 0.805 ± 0.267 L/min/kg, 110.284 ± 94.176 L/kg, and 732.919 ± 847.32 min for gavage administration of 10mg/kg , respectively. The results indicate that Tet displays a limited absorption in intestinal tract, even though it has a favorable pharmacokinetic profile after oral or intravenous administration.

Simple, sensitive and rapid HPLC-MS/MS method for the determination of cepharanthine in human plasma.

A rapid, sensitive and specific method for the determination of cepharanthine in human plasma using high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) was described. Cepharanthine and the internal standard (I.S.), telmisartan, were extracted from human plasma by methanol to precipitate the protein. A centrifuged upper layer was then evaporated and reconstituted with 100µL methanol. Chromatographic separation was performed on an AGILENT XDB-C(8) column (150mm×2.1mm, 5.0µm, Agilent, USA) using a gradient mobile phase with 1mmol/L ammonium acetate in water with 0.05% formic acid and methanol. Detection and quantitation was performed by MS/MS using electrospray ionization (ESI) and multiple reaction monitoring (MRM) in the positive ion mode. The most intense [M+H](+) MRM transition of cepharanthine at m/z 607.3→365.3 was used for quantitation and the transition at m/z 515.5→276.4 was used to monitor telmisartan. The calibration curve was linear within the concentration range of 0.5-200.0ng/mL (r=0.9994). The limit of quantification (LOQ) was 0.5ng/mL. The extraction recovery was above 81.1%. The accuracy was higher than 92.3%. The intra- and inter-day precisions were less than 9.66%. The method was accurate, sensitive and simple and was successfully applied to a pharmacokinetic study after single intravenous administration of 50mg cepharanthine in 12 healthy Chinese volunteers.

Validated liquid chromatography-tandem mass spectrometry method for quantitative determination of dauricine in human plasma and its application to pharmacokinetic study.

A highly sensitive and selective LC-MS/MS method was developed and validated for the determination of dauricine in human plasma, using protopine as internal standard (IS). The analyte and IS were extracted by liquid-liquid extraction and analyzed by LC-MS/MS. Chromatographic separation was performed on Agilent TC-C(18) column with a mobile phase of methanol-water-glacial acetic acid (60:40:0.8, v/v/v) at a flow rate of 0.7 mL/min. Detection was performed on a triple quadrupole tandem mass spectrum by multiple reaction monitoring (MRM) mode using the electrospray ionization technique in positive mode. The method was linear over the concentration range of 1-200 ng/mL. The lower limit of quantification (LLOQ) was 1 ng/mL in human plasma with acceptable precision and accuracy. The intra- and inter-day precision was less than 5.9% determined from quality control (QC) samples at concentrations of 2.0, 20.0 and 160 ng/mL, and the accuracy was within +/-9.9%. This method was successfully applied for the evaluation of pharmacokinetics of dauricine after oral doses of 100, 300 and 600 mg phenolic alkaloids of menispermum dauricum tablet (PAMDT) to 12 Chinese healthy volunteers.

Evaluation of tetrandrine sustained release calcium alginate gel beads in vitro and in vivo.

An approach for the preparation of tetrandrine sustained release calcium alginate gel beads was described. In vitro the release of tetrandrine from sustained release dosage forms went on a time of 12 hours which fitted non-Fickian diffusion with matrix erosion significantly. In vivo the plasma concentration of tetrandrine extended preparation given in dogs reached Cmax 2.67+/-0.69 microg/ml approximately at 5.67+/-0.58 h after oral administration. The AUC0-->24 and AUC0-->infinity were 24.64+/-6.77 mg.h/l and 29.75+/-5.30 mg.h/l, respectively. The elimination half-time was 9.6+/-2.40 h. While a favorable correlation existed between in vitro and in vivo with a correlative coefficient of 0.9798 through linear regression. An investigation on the quantitative relationship between in vitro release and in vivo absorption is a highly necessary work guided for manufacture, optimization and in vivo evaluation of sustained release dosage by means of in vitro release or dissolution tests.