An ultra high performance liquid chromatography with tandem mass spectrometry method for plasma and cerebrospinal fluid pharmacokinetics of rhein in patients with traumatic brain injury after administration of rhubarb decoction

Damage of blood–brain barrier is a common result of traumatic brain injury. This damage can open the blood–brain barrier and allow drug passage. An ultraperformance liquid chromatography with tandem mass spectrometry method was established to determine the concentration of rhein in the biofluids (plasma and cerebrospinal fluid) of patients with a compromised blood–brain barrier following traumatic brain injury after rhubarb administration. Furthermore, the pharmacokinetic profiles were analyzed. A triple‐quadruple tandem mass spectrometer with electrospray ionization was used for rhein detection. The mass transition followed was m/z 283.06→239.0. The calibration curve was linear in the concentration range of 10–8000 ng/mL for the biofluids. The intra‐ and interday precisions were less than 10%. The relative standard deviation of recovery was less than 15% in biological matrices. The pharmacokinetic data showed that rhein was rapidly transported into biofluids, and exhibited a peak concentration 1 h after rhubarb administration. The elimination rate of rhein was slow. The AUC_{cerebrospinal fluid}/AUC_plasma (AUC is area under curve) of rhein was approximately 17%, indicating that portions of rhein could pass the impaired blood–brain barrier. The method was successfully applied to quantify rhein in the biofluids of all patients. The data presented can help to guide clinical applications of rhubarb for treating traumatic brain injury.     

Pharmacokinetic properties of wogonin and its herb–drug interactions with docetaxel in rats with mammary tumors

Docetaxel, frequently used for the treatment of breast cancer, is mainly metabolized via hepatic cytochrome P450 (CYP) 3A in humans and is also a substrate of P‐glycoprotein (P‐gp). Wogonin has been shown to be able to modulate the activities of CYPs and P‐gp, and it could serve as an adjuvant chemotherapeutic agent. However, the impacts of co‐administration of wogonin and docetaxel on their pharmacokinetics have not been studied because of a lack of an analytical method for their simultaneous measurement. In the present study, we established an HPLC–MS/MS method for simultaneous measurement of wogonin and docetaxel in rat plasma, and it was then utilized to explore the pharmacokinetics of wogonin and the herb–drug interactions between wogonin and docetaxel after their combined administration in rats with mammary tumors. The rats received 10, 20 and 40 mg/kg wogonin via oral administration, with or without docetaxel intravenously administered at 10 mg/kg, and the plasma concentrations of wogonin and docetaxel were measured using the established and validated HPLC–MS/MS method. The C_max and AUC_0–t of wogonin were proportionally increased in the dose range from 10 to 40 mg/kg, suggesting a linear pharmacokinetics of wogonin. Moreover, the C_max and AUC_0–t of docetaxel and the AUC_0–t of wogonin were increased after co‐administration (p < 0.05), indicating increased in vivo exposures of both wogonin and docetaxel, which might lead to an increase in not only therapeutic but also toxic effects. Thus the alterations of pharmacokinetics should be taken into consideration when wogonin and docetaxel are co‐administered.     

A sensitive UPLC–MS/MS method for simultaneous determination of polyphenols and theaflavins in rat plasma: Application to a pharmacokinetic study of Da Hong Pao tea

A method based on ultra‐performance liquid chromatography–tandem mass spectrometry has been developed for the rapid and simultaneous determination of five catechins and four theaflavins in rat plasma using ethyl gallate as internal standard. The pharmacokinetic profiles of these compounds were compared after oral administration of five kinds of Da Hong Pao tea to rats. Biosamples processed with a mixture of β‐glucuronidase and sulfatase were extracted with ethyl acetate–isopropanol. Chromatographic separation was achieved by gradient elution using 10 mm HCOONH₄ solution and methanol as the mobile phase. Analytes were detected using negative ion electrospray ionization in multiple reaction monitoring mode. The lower limits of quantification were 1.0, 0.74 and 0.5 ng/mL for theaflavins, two catechins and three catechins, respectively. The validation parameters were well within acceptable limits. The average half‐lives (t_1/2) in blood of the reference solution group was much shorter than those of tea samples. The values of AUC_0–t and C_max of the polyphenols and theaflavins exhibited linear pharmacokinetic characteristics which were related to the dose concentration.     

Simultaneous determination of paeoniflorin from total glucosides of paeony in Sprague–Dawley rats and spontaneously hypertensive rats by high‐performance liquid chromatography–tandem mass spectrometry: in vivo and in vitro studies

Paeoniflorin is a well‐known monoterpene glucoside in the herbal drug that exhibits a number of biological activities. The pharmacokinetic characteristics of paeoniflorin from total glucosides of paeony in spontaneously hypertensive rats (SHR) are still unclear. It is essential to investigate the in vivo and in vitro pharmacokinetic differences of paeoniflorin from total glucosides of paeony in Sprague–Dawley (SD) and SHR. The in vivo pharmacokinetic data were analyzed using DAS 2.0 software and the in vitro metabolic characteristics were measured using rat hepatic microsomes. The concentration of paeoniflorin in biological samples was determined using high‐performance liquid chromatography–electrospray ionization tandem mass spectrometry method, which showed good precision and stability. The plasma concentration–time profiles of paeoniflorin following oral administration of total glucosides of paeony showed a single peak and there were significant differences in the mean values of AUC_(0–t), AUC_(0–∞), CL_z/F and T_max between SD and SHR (p < 0.05). The metabolic rate of paeoniflorin from total glucosides of paeony was slower in SHR than in SD rats (p < 0.05). The results might be useful in further applications of paeoniflorin and total glucosides of paeony. Copyright © 2016 John Wiley & Sons, Ltd.     

Comparative pharmacokinetic study of the main components of cortex fraxini after oral administration in normal and hyperuricemic rats

Cortex Fraxini is an important traditional Chinese herbal medicine used for the treatment of gout and hyperuricemia. An efficient and rapid ultra‐performance liquid chromatography mass spectrometry method was developed and validated for simultaneous quantitation of six coumarins (aesculin, fraxin, aesculetin, fraxetin, sopoletin and 7‐hydroxycoumarin) in normal and hyperuricemic rats plasma after oral administration of Cortex Fraxini. The method could successfully be applied for pharmacokinetics studies. The pharmacokinetic behavior of six coumarins in normal and hyperuricemia rats plasma was determined. Results showed that, for some of analytes, the pharmacokinetic parameters (AUC_0–t , AUC_0–∞, C _max, T _max and CL ) were significantly different between normal and hyperuricemic rats. The different pharmacokinetic parameters might result from renal impairment or a change of metabolic enzymes in the pathological state. The pharmacokinetic study in pathological state could provide more useful information to guide the clinical use of traditional Chinese herbal medicine.     

Comparative pharmacokinetics of nine major bioactive components in normal and ulcerative colitis rats after oral administration of Lizhong decoction extracts by UPLC–TQ–MS/MS

Lizhong decoction (LZD), a classic formula, has been used to treat ulcerative colitis (UC) for thousands of years in clinical practice. However, the pharmacokinetic characteristics of its major bioactive components in rats under different physiological and pathological states are not clear. Thus, in this study, a rapid and sensitive analytical method, ultra‐performance liquid chromatography coupled with mass spectrometry (UPLC–MS/MS) method, was developed and applied to simultaneously determine glycyrrhizic acid, liquiritin, isoliquiritin, glycyrrhizin, isoliquiritigenin, 6‐gingerol, ginsenoside Rg1, ginsenoside Rb1 and ginsenoside Re in normal and UC rats after oral administration of LZD extract. A Waters BEH C₁₈ UPLC column was used for chromatographic separation, while acetonitrile and 0.1% formic acid were selected as mobile phase. The linearity of nine analytes was >0.9920. Inter‐ and intra‐day accuracy was ≤ 11.4% and precision was from 1.1 to 12.7%. Additionally, stable and suitable extraction recoveries were also obtained. The established method was validated and found to be specific, accurate and precise for nine analytes. Furthermore, it was successfully applied to the pharmacokinetic investigation of nine major components after oral administration of LZD extracts to normal and model rats, respectively. The results showed that the pharmacokinetic parameters (C_max, T_max, AUC_0–t, AUC_0–∞) in the plasma of UC rats were significantly different from those of normal rats, which could provide a reference for the clinical application of LZD.     

A UFLC–MS/MS method for the simultaneous determination of eight bioactive constituents from red wine and dealcoholized red wine in rat plasma: Application to a comparative pharmacokinetic study

To explore whether alcohol has an effect on the pharmacokinetic behavior of phenolic acids, the main bioactive constituents in red wine, a highly sensitive and simple ultra‐fast liquid chromatography coupled with triple quadrupole mass spectrometry (UFLC–MS/MS) method was developed for simultaneous quantitation of eight phenolic acids in plasma samples. Plasma samples were extracted by liquid–liquid extraction and the chromatographic separation was achieved on a Zorbax SB‐C₁₈ column within 7.0 min. Results of the validated method revealed that all of the calibration curves displayed good linear regression (r > 0.99). The intra‐ and inter‐day precisions of the analytes were <14.0% and accuracies ranged from ?8.5 to 7.3%. The extraction recoveries of the analytes were from 71.2 to 110.2% and the matrix effects ranged from 86.2 to 105.5%. The stability of these compounds under various conditions satisfied the requirements of biological sample measurement. The method was successfully applied to a comparative pharmacokinetic study of phenolic acids in rat plasma. For gallic acid and gentisic acid, the parameters AUC_0–t and AUC_0–∞ increased remarkably (p < 0.05) after oral administration of red wine, which suggested that alcohol might enhance their absorption. This is the first report to compare the pharmacokinetic behavior of phenolic acids in red wine and dealcoholized red wine.     

Comparative pharmacokinetics studies of benzoylhypaconine,benzoylmesaconine, benzoylaconine and hypaconitine in rats by LC‐MS method after administration of Radix Aconiti Lateralis Praeparata extract and Dahuang Fuzi Decoction

A rapid and sensitive high‐performance liquid chromatography–mass spectrometric (HPLC‐MS) method was developed and validated for simultaneous determination of benzoylhypaconine (BHA), benzoylmesaconine (BMA), benzoylaconine (BAC) and hypaconitine (HA) in rat plasma for the first time. The analytes were separated on a Kromasil C₁₈ column with a total running time of 11 min. The validation data demonstrated a sound feasibility for the newly developed method and it was then applied to the pharmacokinetic study of these analytes in rats. Pharmacokinetic behaviors of BHA, BMA, BAC and HA in rats were studied after oral administration of Radix Aconiti Lateralis Praeparata extract (FZ) and Dahuang Fuzi Decoction (DFD). The main parameters for the two groups of subjects were compared, and significant differences between Radix Aconiti Lateralis Praeparata extract group and Dahuang Fuzi Decoction group in calculated parameters, such as the area under the plasma concentration–time from zero to the last quantifiable time‐point (AUC_0–t), the area under the plasma concentration–time curve from zero to infinity (AUC_0–∞), peak plasma concentration (C_max), half‐life of elimination (T_1/2), mean retention time (MRT_0–t), plasma clearance (CL), volume of distribution (V_d) and time to reach C_max (T_max), were found. After oral administration of DFD, the AUC_0–t, AUC_0–∞ and C_max of BHA, BMA, BAC and HA decreased remarkably (p < 0.05) compared with those of the FZ extract group. V_d and CL values of BHA, BMA, BAC and HA increased, two of which showed significant difference (p < 0.05). T_1/2 and MRT_0–t values of BHA, BMA and BAC in the DFD group were significantly delayed compared with those of FZ extract group. Only the T_max of HA, the toxic ingredient in FZ, delayed significantly in DFD group compared with the value of FZ group. All these pharmacokinetic parameters were statistically compared, and the rationality of the combination for DFD was clearly demonstrated. Copyright © 2013 John Wiley & Sons, Ltd.     

Pharmacokinetics of anthraquinones in rat plasma after oral administration of a rhubarb extract

A sensitive and specific LC‐MS/MS method was developed for simultaneous determination of aloe‐emodin, rhein, emodin, chrysophanol and physcion and their conjugates in rat plasma. The lower limit of quantitation of each anthraquinone was 0.020–0.040 µm . Intra‐day and inter‐day accuracies were 90.1–114.3% and the precisions were <14.6%. The matrix effects were 104.0–113.2%. The method was successfully applied to a pharmacokinetic study in rats receiving a rhubarb extract orally. The area under the concentration–time curve (AUC_0–t) and peak concentration (C_max) of free aloe‐emodin and emodin in rat plasma were much lower than those of rhein. The amounts of chrysophanol and physcion were too low to be continuously detected. After treating the plasma samples with β‐glucuronidases, each anthraquinone was detectable throughout the experimental period (36 h) and showed much higher plasma concentrations and AUC_0–t. The free/total ratios of aloe‐emodin, rhein and emodin were 6.5, 49.0 and 1.7% for C_max and 3.7, 32.5 and 1.1% for AUC_0–t, respectively. The dose‐normalized AUC_0–t and C_max of the total of each anthraquinone were in the same descending order: rhein > emodin > chrysophanol > physcion > aloe‐emodin. These findings reveal phase II conjugates as the dominant in vivo existing forms of rhubarb antharquinones and warrant a further study to evaluate their contribution to the herbal activity. Copyright © 2013 John Wiley & Sons, Ltd.     

Drug–drug interactions between moxifloxacin and rifampicin based on pharmacokinetics in vivo in rats

Moxifloxacin and rifampicin are all the first‐line options for the treatment of active tuberculosis, which are often combined for the treatment of multidrug resistance pulmonary tuberculosis in clinic. However, the potential drug–drug interactions between moxifloxacin and rifampicin were unknown. The aim of this study was to investigate the drug–drug interactions between moxifloxacin and rifampicin based on their pharmacokinetics in vivo after oral administration of the single drug and both drugs, and reveal their mutual effects on their pharmacokinetics. Eighteen male Sprague–Dawley rats were randomly assigned to three groups: moxifloxacin group, rifampicin group and moxifloxacin + rifampicin group. Plasma concentrations of moxifloxacin and rifampicin were determined using LC‐MS at the designated time points after drug administration, and the main pharmacokinetic parameters were calculated. In addition, effects of moxifloxacin and rifampicin on their metabolic rate and absorption were investigated using rat liver microsome incubation systems and Caco‐2 cell transwell model. The main pharmacokinetic parameters of moxifloxacin including T_max, C_max, t_1/2 and AUC_(0–t) increased more in the moxifloxacin + rifampicin group than in the moxifloxacin group, but the difference was not significant (p > 0.05). However, the pharmacokinetic parameters of rifampicin, including peak concentration, area under the concentration–time curve, half‐life and the area under the first moment plasma concentration–time curve, increased significantly (p < 0.05) compared with the rifampicin group, and the time to peak concentration decreased significantly (p < 0.05). The mean residence time of rifampicin also increased in moxifloxacin + rifampicin group compared with the rifampicin group, but the difference was not significant (p > 0.05). The rat liver microsome incubation experiment indicated that moxifloxacin could increase the metabolic rate of rifampicin from 23.7 to 38.7 min. However, the Caco‐2 cell transwell experiment showed that moxifloxacin could not affect the absorption rate of rifampicin. These changes could enhance the drug efficacy, but they could also cause drug accumulation, which might induce adverse effect, so it was suggested that the drug dosage should be adjusted and the drug concentration in plasma should be monitored if moxifloxacin and rifampicin are co‐administered. Copyright © 2016 John Wiley & Sons, Ltd.     

Comparative pharmacokinetics of prim-O-glucosylcimifugin and cimifugin by liquid chromatography-mass spectrometry after oral administration of Radix Saposhnikoviae extract, cimifugin monomer solution and prim-O-glucosylcimifugin monomer solution to rats

A sensitive and reliable liquid chromatography–mass spectrometry method has been developed and validated for simultaneous determination of cimifugin and prim‐O‐glucosylcimifugin in rat plasma after oral administration of Radix Saposhnikoviae (RS) extract, prim‐O‐glucosylcimifugin monomer solution and cimifugin monomer solution. Plasma samples were pretreated by protein precipitation with acetonitrile containing the internal standards puerarin and daidzein. LC separation was achieved on a Zorbax SB‐C₁₈ column (150 × 4.6 mm i.d., 5 µm) with 0.1% formic acid in water and methanol by isocratic elution. The detection was carried out in select‐ion‐monitoring mode with a positive electrospray ionization interface. The fully validated method was successfully applied to the pharmacokinetic study of the analytes in rats. A bimodal phenomenon appeared in the concentration–time curve of prim‐O‐glucosylcimifugin and cimifugin after oral administration of RS extract. Prim‐O‐glucosylcimifugin mainly transformed to cimifugin when it was absorbed into blood. Both absorption and elimination of cimifugin after oral administration of RS were longer than after administration of single cimifugin. The pharmacokinetic parameters (AUC_0–t, AUC_0–∞ and t_1/2) of prim‐O‐glucosylcimifugin and cimifugin by giving cimifugin monomer solution, prim‐O‐glucosylcimifugin monomer solution and RS extract had significant differences (P < 0.05). Copyright © 2012 John Wiley & Sons, Ltd.     

Pharmacokinetic profile of ivabradine hemisulfate sustained‐release tablets administered in Chinese healthy volunteers: An open‐label,randomized, single‐dose,three‐period crossover study

We aimed to determine the pharmacokinetics and safety of three single oral doses (5, 10 and 15 mg) of ivabradine hemisulfate sustained‐release tablets in healthy Chinese volunteers. A total of 12 volunteers (six males and six females) were randomized to receive a single oral dose of ivabradine hemisulfate sustained‐release tablets 5, 10 or 15 mg, with a 1‐week washout between periods. Blood samples were collected at regular intervals from 0 to 48 h after drug administration, and the concentrations of ivabradine and N‐desmethyl ivabradine were determined by HPLC–tandem mass spectrometry. Pharmacokinetic parameters were estimated by non‐compartmental analysis. After administering single doses of 5, 10 and 15 mg, the mean maximum concentration (C_max) levels of ivabradine were 4.36, 7.29 and 12.62 ng/mL, and the mean area under the curve from time 0 to 48 h (AUC_0–48) values were 55.66, 101.16 and 182.09 h·ng/mL, respectively. The mean C_max levels of N‐desmethyl ivabradine were 1.05, 2.03 and 3.16 ng/mL, and the mean AUC_0–48 values were 20.61, 39.44 and 65.72 h·ng/mL, respectively. The median time of maximum concentration (T_max) levels of ivabradine and N‐desmethyl ivabradine were 5 h for all three doses tested. The pharmacokinetic properties of ivabradine hemisulfate sustained‐release tablets were linear at doses from 5 to 15 mg. Ivabradine hemisulfate sustained‐release tablet appears to be well tolerated in these healthy volunteers.     

The effect of tripterygium glucoside tablet on pharmacokinetics of losartan and its metabolite EXP3174 in rats

Losartan and tripterygium glucoside tablet (TGT) are often simultaneously used for reducing urine protein excretion in clinic. However, it is unknown whether there is potential herb–drug interaction between losartan and TGT. The aim of this study was to investigate their potential herb–drug interaction, and clarify the mechanism of the effect of TGT on the pharmacokinetics of losartan and its metabolite EXP3174 in rats. The plasma concentrations of losartan and EXP3174 were determined by LC–MS, and the main pharmacokinetic parameters were calculated. The C _max, t _1/2 and AUC_{(0–t )} of losartan became larger after co‐administration, while the C _max and AUC_{(0–t )} of EXP3174 became smaller, suggesting that TGT could influence the pharmacokinetics of losartan and EXP3174. The effects of TGT and its main components on the metabolic rate of losartan were further investigated in rat liver microsomes. Results indicated that TGT and its two main ingredients could decrease the metabolic rate of losartan. Therefore, it was speculated that TGT might increase the plasma concentration of losartan and decrease the concentration of EXP3174 by inhibiting the metabolism of losartan. The results could provide references for clinical medication guidance of losartan and TGT to avoid the occurrence of adverse reactions.     

Simultaneous determination of epalrestat and puerarin in rat plasma by UHPLC–MS/MS: Application to their pharmacokinetic interaction study

In the present study, a simple, rapid and reliable ultrahigh‐performance liquid chromatography–tandem mass spectrometric (UHPLC–MS/MS) method was developed and validated to determine simultaneously epalrestat (EPA) and puerarin (PUE) in rat plasma for evaluation of the pharmacokinetic interaction of these two drugs. Both the analytes and glipizide (internal standard, IS) were extracted using a protein precipitation method. The separation was performed on a C18 reversed phase column using acetonitrile and 5 mmol/L ammonium acetate in water as the mobile phase with a gradient elution program. The analytes, including IS, were quantified with multiple reaction monitoring under negative ionization mode. The optimized mass transition ion pairs (m /z ) were 318.1 → 274.0 for EPA, 415.1 → 266.9 for PUE and 444.2 → 166.9 for IS. The linear calibration curves for EPA and PUE were obtained in the concentration ranges of 10–4167 and 20–8333 ng/mL, respectively (r > 0.99). The current method was successfully applied for the pharmacokinetic interaction study in rats following administration of EPA and PUE alone or co‐administration (EPA 15 mg/kg, oral; PUE 30 mg/kg, intravenous). The results showed that the combination of EPA and PUE could increase t _1/2 of EPA and reduce T _max of EPA. These changes indicated that EPA and PUE might cause drug–drug interactions when co‐administrated.     

LC‐MS/MS determination of bakkenolide D in rats plasma and its application in pharmacokinetic studies

A sensitive and rapid liquid chromatography–tandem mass spectrometry (LC‐MS/MS) method was developed and validated for determination of bakkenolide D (BD), which was further applied to assess the pharmacokinetics of BD. In the LC‐MS/MS method, the multiple reaction monitoring mode was used and columbianadin was chosen as internal standard. The method was validated over the range of 1–800 ng/mL with a determination coefficient >0.999. The lower limit of quantification was 1 ng/mL in plasma. The intra‐ and inter‐day accuracies for BD were 91–113 and 100–104%, respectively, and the inter‐day precision was <15%. After a single oral dose of 10 mg/kg of BD, the mean peak plasma concentration of BD was 10.1 ± 9.8 ng/mL at 2 h. The area under the plasma concentration–time curve (AUC_{0–24 h}) was 72.1 ± 8.59 h ng/mL, and the elimination half‐life (T_1/2) was 11.8 ± 1.9 h. In case of intravenous administration of BD at a dosage of 1 mg/kg, the AUC_{0–24 h} was 281 ± 98.4 h?ng/mL, and the T_1/2 was 8.79 ± 0.63 h. Based on these results, the oral bioavailability of BD in rats at 10 mg/kg is 2.57%. Copyright © 2013 John Wiley & Sons, Ltd.     

Pharmacokinetics of TAK‐875 and its toxic metabolite TAK‐875‐ acylglucuronide in rat plasma by liquid chromatography tandem mass spectrometry

TAK‐875 is a selective partial agonist of human GPR40 receptor, which was unexpectedly terminated at phase III clinical trials owing to its severe hepatotoxicity. The purpose of this study was to investigate the pharmacokinetics of TAK‐875 and its toxic metabolite TAK‐875‐acylglucuronide in rat plasma by liquid chromatography tandem mass spectrometry (LC–MS/MS). Plasma samples were extracted with ethyl acetate and chromatographic separations were achieved on a C₁₈ column with water and acetonitrile containing 0.05% ammonium hydroxide as mobile phase. The sample was detected in selected reaction monitoring mode with precursor‐to‐product ion transitions being m/z 523.2 → 148.1, m/z 699.3 → 113.1 and m/z 425.2 → 113.1 for TAK‐875, TAK‐875‐acylglucuronide and IS, respectively. The assay showed good linearity over the tested concentration ranges (r > 0.9993), with the LLOQ being 0.5 ng/mL for both analytes. The extraction recovery was >78.45% and no obvious matrix effect was detected. The highly sensitive LC–MS/MS method has been further applied for the pharmacokinetic study of TAK‐875 and its toxic metabolite TAK‐875‐acylglucuronide in rat plasma. Pharmacokinetics results revealed that oral bioavailability of TAK‐875 was 86.85%. The in vivo exposures of TAK‐875‐acylglucuronide in terms of AUC_0–t were 17.54 and 22.29% of that of TAK‐875 after intravenous and oral administration, respectively.     

Pharmacokinetic study of five ginsenosides using a sensitive and rapid liquid chromatography–tandem mass spectrometry method following single and multiple oral administration of Shexiang Baoxin pills to rats

Shexiang Baoxin pills (SBP) are a traditional Chinese medicine that are used for treating coronary heart disease. Ginsenosides are the main effective components of SBP, but a comprehensive and deep pharmacokinetic study of ginsenosides in SBP, including multiple dosing and linear or nonlinear properties, is lacking. This study was designed to investigate and compare the pharmacokinetic characteristics of ginsenosides in SBP at a single dose and in multiple doses. A liquid chromatography–tandem mass spectrometry (LC‐MS/MS) method was developed for the simultaneous determination of the ginsenosides Rg1, Re, Rb3, Rc and Rb1 in rat plasma. Rats were randomly assigned to receive a single dose of 4, 8 or 12 g/kg and multiple doses (4 g/kg) of SBP for 8, 15 or 22 consecutive days. The results revealed that ginsenosides, following a single oral dose of 4 or 8 g/kg, were absorbed rapidly, with a T_max ranging from 0.250 to 1.08 h. The AUC_0–t and C_max of the ppd‐type ginsenosides Rb3, Rc and Rb1 were greater than those of the ppt‐type ginsenosides Rg1 and Re. Nondose‐dependent exposure was observed at doses of 4–12 g/kg for all of the ginsenosides. After multiple dosing, the plasma levels of the ppt‐type ginsenosides decreased, whereas those of the ppd‐type ginsenosides did not change significantly. In conclusion, the LC‐MS/MS method was successfully applied to investigate the pharmacokinetics of ginsenosides after single and multiple oral administrations of SBP. The ginsenosides did not accumulate after multiple dosing. The ppd‐type ginsenosides displayed more favorable pharmacokinetic properties compared with the ppt‐type ginsenosides. Copyright © 2014 John Wiley & Sons, Ltd.     

A self‐contrast approach to evaluate the inhibitory effect of chrysosplenetin,in the absence and presence of artemisinin,on the in vivo P‐glycoprotein‐mediated digoxin transport activity

In this study, we used a self‐contrast method, which excluded the individual difference, to evaluate the inhibitory effect of chrysosplentin (CHR) in the presence or absence of artemisinin (ART) on the P‐glycoprotein (P‐gp) transport activity. A sensitive and rapid UHPLC–MS/MS method was applied for quantification of digoxin, a P‐gp‐specific substrate, in rat plasma. A pharmacokinetic study was carried out: first after an oral administration of digoxin at a dose of 0.09 mg/kg (first period), followed by a 20‐day wash‐out, then after another administration of digoxin (second period). During the second period, test compounds were orally given three times per day for seven consecutive days. Results showed that the t_1/2 of digoxin in all the groups had no significant difference between the first and second periods. The AUC_0–24, C_max, t_max, and Cl_z/F of the negative control and ART alone groups showed no difference. However, the AUC_0–24 and C_max in the CHR alone, CHR–ART (1:2) and verapamil (positive control) groups showed 2.34‐, 3.04‐, 1.79‐, and 1.81‐, 1.99‐, 2.06‐fold increases along with 3.50‐, 3.84‐ and 4.76‐fold decreases for CL_z/F, respectively. The t_max in the CHR–ART (1:2) group increased 3.73‐fold. In conclusion, our self‐contrast study suggested that CHR, especially when combined with ART in a ratio of 1:2, inhibited P‐gp activity while ART alone has no effect. Copyright © 2016 John Wiley & Sons, Ltd.     

UPLC–MS/MS simultaneous determination of seven active ingredients of Yaobitong capsule in rat plasma and its integrated pharmacokinetic application

A reliable and sensitive UPLC–MS/MS method was first established and validated for the simultaneous determination of seven active ingredients of Yaobitong capsule in rat plasma: ginsenoside Rg1, ginsenoside Rb1, osthole, tetrahydropalmatine, paeoniflorin, albiflorin, and ferulic acid. And this method was further applied for the integrated pharmacokinetic study of Yaobitong capsule in rats after oral administration. Plasma samples (100 μL) were precipitated with 300 μL of methanol using carbamazepine as internal standard. Chromatographic separation was achieved using an Aquity UPLC BEH C18 column (100 × 2.1 mm, 1.7 μm), with the mobile phase consisting of 0.1% formic acid and acetonitrile. The method was validated using a good linear relationship (r ≥ 0.991), and the lower limit of quantification of the analytes ranged from 0.5 to 40 ng/mL. In the integrated pharmacokinetic study, the weight coefficient was calculated by the ratio of AUC_0–∞ of each component to the total AUC_0–∞ of the seven active ingredients. The integrated pharmacokinetic parameters C_max, T_max, and t_1/2 were 81.54 ± 9.62 ng/mL, 1.00 ± 0.21 h, and 3.26 ± 1.14 h, respectively. The integration of pharmacokinetic parameters showed a shorter t_1/2 because of fully considering the contribution of the characteristics of each active ingredient to the overall pharmacokinetics.     

A sensitive UPLC–MS/MS method for simultaneous determination of polyphenols in rat plasma: Application to a pharmacokinetic study of dispensing granules and standard decoction of Cinnamomum cassia twigs

This study established a rapid and reliable approach using liquid chromatography–tandem mass spectrometry for the simultaneous determination of cinnamic acid, vanillic acid and protocatechuic acid in rat plasma. This is the first report on a comparative pharmacokinetic study of dispensing granules and standard decoction of Cinnamomum cassia twigs in rats. After liquid–liquid extraction by ethyl acetate, the plasma samples were subjected to LC–MS/MS for multiple reaction monitoring. The standard curves showed good linear regression (r² > 0.9991) in the range of 10.0–16000 ng/mL. The intra‐ and inter‐day accuracy and precision were found to be within 15% of the nominal concentration. The recoveries of the three phenolics ranged from 88.7 to 105.7%. Finally, this approach was successfully applied to pharmacokinetic analysis of the three phenolics after oral administration of standard decoction and dispensing granules of C. cassia twigs in rats. Although the values of AUC_0–t of vanillic acid and protocatechuic acid in standard decoction group were larger than those of the dispensing granule group, no significant difference was observed for the two groups. Of note, the elimination rates of vanillic acid were slower in the standard decoction group than the dispensing granule group.