Physiologically Based Pharmacokinetic Modeling to Unravel the Drug-gene Interactions of Venlafaxine: Based on Activity Score-dependent Metabolism by CYP2D6 and CYP2C19 Polymorphisms.

BACKGROUND: Venlafaxine (VEN) is a commonly utilized medication for alleviating depression and anxiety disorders. The presence of genetic polymorphisms gives rise to considerable variations in plasma concentrations across different phenotypes. This divergence in phenotypic responses leads to notable differences in both the efficacy and tolerance of the drug. PURPOSE: A physiologically based pharmacokinetic (PBPK) model for VEN and its metabolite O-desmethylvenlafaxine (ODV) to predict the impact of CYP2D6 and CYP2C19 gene polymorphisms on VEN pharmacokinetics (PK). METHODS: The parent-metabolite PBPK models for VEN and ODV were developed using PK-Sim® and MoBi®. Leveraging prior research, derived and implemented CYP2D6 and CYP2C19 activity score (AS)-dependent metabolism to simulate exposure in the drug-gene interactions (DGIs) scenarios. The model's performance was evaluated by comparing predicted and observed values of plasma concentration-time (PCT) curves and PK parameters values. RESULTS: In the base models, 91.1%, 94.8%, and 94.6% of the predicted plasma concentrations for VEN, ODV, and VEN + ODV, respectively, fell within a twofold error range of the corresponding observed concentrations. For DGI scenarios, these values were 81.4% and 85% for VEN and ODV, respectively. Comparing CYP2D6 AS = 2 (normal metabolizers, NM) populations to AS = 0 (poor metabolizers, PM), 0.25, 0.5, 0.75, 1.0 (intermediate metabolizers, IM), 1.25, 1.5 (NM), and 3.0 (ultrarapid metabolizers, UM) populations in CYP2C19 AS = 2.0 group, the predicted DGI AUC0-96 h ratios for VEN were 3.65, 3.09, 2.60, 2.18, 1.84, 1.56, 1.34, 0.61, and for ODV, they were 0.17, 0.35, 0.51, 0.64, 0.75, 0.83, 0.90, 1.11, and the results were similar in other CYP2C19 groups. It should be noted that PK differences in CYP2C19 phenotypes were not similar across different CYP2D6 groups. CONCLUSIONS: In clinical practice, the impact of genotyping on the in vivo disposition process of VEN should be considered to ensure the safety and efficacy of treatment.

In vitro Assessment of the Effects of Silybin on CYP2B6-mediated Metabolism.

Silybin is a flavonol compound with a variety of physiological properties, such as hepatoprotective, anti-fibrogenic, and hypocholesterolemic effects. Although the in vivo and in vitro effects of silybin are frequently reported, studies on herb-drug interactions have yet to be performed. With the discovery of multiple important substrates of CYP2B6 recently, there is a growing body of evidence indicating that CYP2B6 plays a much larger role in human drug metabolism than previously thought.The purpose of this study is to determine how silybin affects the CYP2B6 enzyme's activity, as well as to clarify the molecular mechanisms for inhibition by silybin. The results showed that silybin inhibited CYP2B6 activity in liver microsomes in a non-competitive manner, with IC50 and Ki values of 13.9 µM and 38.4 µM, respectively. Further investigations revealed that silybin could down-regulate the expression of CYP2B6 protein in HepaRG cells. The hydrogen bond conformation of silybin in the active site of the CYP2B6 isoform was revealed by a molecular docking study. Collectively, our findings verify that silybin is an inhibitor of CYP2B6 and explain the molecular mechanism of inhibition. This can lead to a better understanding of the herb-drug interaction between silybin and the substrates of the CYP2B6 enzyme, as well as a more rational clinical use of silybin.

Tanshinone IIA prevents acetaminophen-induced nephrotoxicity through the activation of the Nrf2-Mrp2/4 pathway in mice.

It's known that APAP overdose often leads to hepatotoxicity and nephrotoxicity. In the present study, we investigated the preventative effect of Tan IIA on APAP-induced nephrotoxicity. Mice were orally administrated with Tan IIA (10 or 30 mg/kg/day) for 1 week and subsequently gavaged with 200 mg/kg of APAP. Tan IIA reduced APAP-induced nephrotoxicity as evidenced by histopathological evaluation and serum creatinine levels. Tan IIA pretreatment promoted the efflux of the toxic intermediate metabolite N-acetyl-p-benzoquinone imine (NAPQI), thus reduced its injury to mouse kidney. After Tan IIA pretreatment, a remarkable increase in mRNA and protein expression of Nrf2 and its target genes Mrp2 and Mrp4 was observed in Nrf2+/+ mice kidneys, however, no obvious change of Mrp2 and Mrp4 mRNA and protein expression was detected in Nrf2-/- mice kidneys. HK-2 cells were used for exploring the roles of Tan IIA in the Nrf2-MRPs pathway in vitro. Consistently, Tan IIA up-regulated the Nrf2-MRPs pathway and promoted the nuclear Nrf2 accumulation in HK-2 cells. Collectively, our findings suggested that Tan IIA facilitated the clearance of toxic intermediate metabolite NAPQI from the kidney through upregulation of the Nrf2-MRP2/4 pathway, thereby, performing preventive effects against APAP-induced nephrotoxicity.

Silymarin Protects against Acute Liver Injury Induced by Acetaminophen by Downregulating the Expression and Activity of the CYP2E1 Enzyme.

Previous studies have shown that silymarin protects against various types of drug-induced liver injury, but whether the protective mechanism of silymarin against acetaminophen-induced liver injury is related to the CYP2E1 enzyme remains unclear. In this study, we investigated the effect of silymarin on the activity and expression of CYP2E1 in vitro and in vivo. The results of in vitro studies showed that silymarin not only inhibited the activity of CYP2E1 in human and rat liver microsomes but also reduced the expression of CYP2E1 in HepG2 cells. In vivo studies showed that silymarin pretreatment significantly reduced the conversion of chlorzoxazone to its metabolite 6-OH-CLX and significantly increased the t1/2, area under the curve (AUC) and mean residence time (MRT) of chlorzoxazone. In addition, silymarin pretreatment significantly inhibited the upregulation of Cyp2e1 expression, reduced the production of 3-cysteinylacetaminophen trifluoroacetic acid salt (APAP-CYS), and restored the liver glutathione level. The results of our study show that silymarin plays an important protective role in the early stage of acetaminophen-induced acute liver injury by reducing the activity and expression of CYP2E1, reducing the generation of toxic metabolites, and alleviating liver injury.

Enhanced Cancer-targeted Drug Delivery Using Precoated Nanoparticles.

While protein coronas (PCs) are an important barrier in the clinical application of nanomedicines, the specific effects of PCs on nanoparticles (NPs) in vivo are unclear. Herein, we demonstrated that PCs from clinical sources greatly influenced the active targeting capacities of transferrin-modified NPs (Tf-NPs). Compared to PCs from healthy volunteers, PCs from the plasma of patients with nonsmall cell lung cancer (NSCLC) decreased the A549 uptake of Tf-NPs to a greater degree. The PC proteome revealed that this difference may be mediated by certain proteins in plasma. To attenuate the negative influence of PCs from patients, precoating Tf-NPs with PCs derived from healthy mice significantly enhanced active targeting capacities. Paclitaxel-loaded Tf-NPs with PCs derived from healthy mice showed the strongest antitumor effects in mice with NSCLC. This work illustrates the influence of PCs of ligand-modified NPs in clinical practice and proposes the use of corona-enabled active targeting for precision nanomedicine.

Tanshinone IIA prevents rifampicin-induced liver injury by regulating BSEP/NTCP expression via epigenetic activation of NRF2.

BACKGROUND & AIMS: Rifampicin (RFP)-induced cholestatic liver injury is characterized by impaired hepatic bile acid (BA) transport. Bile salt efflux pump (BSEP) and Na+/taurocholate cotransporter (NTCP) are the major BA transporters. However, little is known about the mechanisms underlying these transporters. METHODS: The role of tanshinone IIA (TAN IIA) in preventing RFP-induced liver injury was evaluated in vitro and in vivo, based on the regulatory mechanism of nuclear factor erythroid 2-related factor 2 (NRF2)-BSEP/NTCP signalling. The epigenetic induction of NRF2 by TAN IIA was investigated as well as the influence on BSEP and NTCP transcriptional activation and NRF2 DNA-binding ability. RESULTS: TAN IIA strongly induced BSEP and NTCP expression in hepatocytes. NRF2 knockdown abrogated the induction. We found two NRF2 binding sites on the human BSEP promoter, called musculoaponeurotic fibrosarcoma recognition elements (MAREs), and one MARE on the NTCP promoter. Human BSEP and NTCP promoter luciferase reporter gene plasmids were stimulated by NRF2. Mutations of the predicted MAREs abolished NRF2 transcriptional activation. TAN IIA induced the expression of ten-eleven translocation 2 (TET2) to mediate the demethylation of NRF2, which promoted NRF2 DNA-binding on the BSEP and NTCP promoters and their transcriptional activation. Finally, in vivo, Nrf2 played an important role in RFP-induced liver injury (more serious liver injury in Nrf2-/- mice), and TAN IIA prevented it. CONCLUSIONS: These results indicate that NRF2 regulates the target transporters BSEP and NTCP, depending on the DNA demethylation by TET2. Pharmacological activation of NRF2 by TAN IIA may be beneficial for RFP-induced liver injury.

Physiologically Based Pharmacokinetic Modeling of Oxycodone in Children to Support Pediatric Dosing Optimization.

PURPOSE: Physiologically-based pharmacokinetic (PBPK) modeling offers a unique modality to predict age-specific pharmacokinetics. The objective of this study was to assess the ability of PBPK model to predict plasma exposure of oxycodone, a widely used opioid for pain management, in adults and children. METHODS: A full PBPK model of oxycodone following intravenous and oral administration was developed using a 'bottom-up' and 'top-down' combined strategy. The model was then extrapolated to pediatrics through a reasonable scaling method. The adult and pediatric model was evaluated using data from 17 clinical PK studies by testing predicted/observed goodness of fit. The mean fold error for PK parameters was calculated. Finally, we used the validated PBPK model to visualize adult-children dose conversion for oxycodone. RESULTS: The developed PBPK model successfully predicted the oxycodone disposition in adults, wherein the predicted versus observed AUC, Cmax, and tmax were within 0.90 to 1.20-fold difference. After scaling anatomy/physiology, protein binding, and clearance, the model showed satisfactory prediction performance for pediatric populations as predicted AUC were within the 1.50-fold range of the observed values. According to the application of PBPK model, we found that different intravenous doses should be given in children of different ages compared to a standard 0.1 mg/kg in adults, while a progressive increasing dose with age growth following oral administration is recommended for children. CONCLUSIONS: The current example provides the opportunity for using the PBPK model to guide dose adjustment of oxycodone in the design of future pediatric clinical studies.

Upregulated OCT3 has the potential to improve the survival of colorectal cancer patients treated with (m)FOLFOX6 adjuvant chemotherapy.

PURPOSE: To investigate the influence of organic cation transporter 3 (OCT3) expression on the effect of the combination regimen of 5-fluorouracil, folinic acid and oxaliplatin ((m)FOLFOX6) in colorectal cancer (CRC) patients. METHODS: This is a retrospective study conducted at a single centre (Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, China). Patients with stage IIb-IV resectable CRC who were being postoperatively treated with (m)FOLFOX6 as a first-line adjuvant chemotherapy regimen for at least 5 cycles and had resected primary tumour samples available were eligible for the study. Patients who preoperatively received chemotherapy and/or radiotherapy or were treated with targeted drugs or other anticancer drugs were excluded from the study. Immunohistochemical staining and digital image analysis were used to assess OCT3 expression in tumour samples. According to OCT3 expression level, the receiver operating characteristic curve (ROC curve) was used to divide the patients into two groups. Cox proportional risk regression was performed with the forward LR (forward stepwise regression based on maximum likelihood estimation) method using SPSS17.0 software. The primary endpoint was the 2-year progression-free survival. RESULTS: In total, 57 patients were included between 2014 and 2016 according to the inclusion and exclusion criteria (22 had low OCT3 expression, and 35 had high OCT3 expression). The mean age was 55.7 (30-74) years, and 37 of the total patients were male. According to TNM stage, 5 patients had stage IV disease, 44 patients had stage III disease, and 8 patients had stage II disease. Through Cox regression analysis, we found that among patients receiving the (m)FOLFOX6 regimen, those with higher OCT3 expression had a higher two-year progression-free survival rate than those with lower OCT3 expression (P = 0.038). The hazard ratio of patients with high OCT3 expression compared with patients with low OCT3 expression was 0.247. Besides, it was found that the age of patients was negatively correlated with expression level of OCT3, which can explain why patients over 70 years do not benefit from oxaliplatin-containing chemotherapy. CONCLUSIONS: High OCT3 expression in CRC tissues may be a protective factor for CRC patients treated with (m)FOLFOX6.

Simultaneous determination of tandospirone and its active metabolite, 1-[2-pyrimidyl]-piperazine in rat plasma by LC-MS/MS and its application to a pharmacokinetic study.

A rapid, sensitive and selective liquid chromatography-tandem mass spectrometry method for the detection of tandospirone (TDS) and its active metabolite 1-[2-pyrimidyl]-piperazine (1-PP) in Sprague-Dawley rat plasma is described. It was employed in a pharmacokinetic study. These analytes and the internal standards were extracted from plasma using protein precipitation with acetonitrile, then separated on a CAPCELL PAK ADME C18 column using a mobile phase of acetonitrile and 5 mm ammonium formate acidified with formic acid (0.1%, v/v) at a total flow rate of 0.4 mL/min. The detection was performed with a tandem mass spectrometer equipped with an electrospray ionization source. The method was validated to quantify the concentration ranges of 1.000-500.0 ng/mL for TDS and 10.00-500.0 ng/mL for 1-PP. Total time for each chromatograph was 3.0 min. The intra-day precision was between 1.42 and 6.69% and the accuracy ranged from 95.74 to 110.18% for all analytes. Inter-day precision and accuracy ranged from 2.47 to 6.02% and from 98.37 to 105.62%, respectively. The lower limits of quantification were 1.000 ng/mL for TDS and 10.00 ng/mL for 1-PP. This method provided a fast, sensitive and selective analytical tool for quantification of tandospirone and its metabolite 1-PP in plasma necessary for the pharmacokinetic investigation.

Formulation conditions on the drug loading properties of polymeric micelles.

Methyl poly(ethylene glycol) grafted poly (lactide-co-(glycolic acid)-alt-(glutamic acid) amphiphilic copolymers (PLG-g-mPEG) were fabricated polymeric micelles to load anticancer drug doxorubicin (DOX). Both blank and drug loaded micelles were spherical nanoparticles with the mean sizes around 50 and 100nm, respectively. The effects of formulation conditions including compositions, concentrations, temperature, feeding doses and solvents on the size and drug loading content were investigated, the storage of the drug loaded micelles was explored. The results showed that the short graft mPEG chain length was favorable for the loading of DOX. The increase of temperature was preferable for receive micelles with higher drug loading content and smaller size. The encapsulation of polymeric micelles could protect the bioactivity of DOX. In vitro drug release profiles illustrated that the drug release from polymeric micelles with long mPEG chains was much faster than from micelles with short mPEG chains. The release kinetics of drug from micelles fitted to the Ritger-Peppas equation well and the release process followed diffusion mechanism.

A reliable LC-MS/MS method for the quantification of N-acetyl-p-benzoquinoneimine, acetaminophen glutathione and acetaminophen glucuronide in mouse plasma, liver and kidney: Method validation and application to a pharmacokinetic study.

A rapid, specific, and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated to simultaneously quantify N-acetyl-p-benzoquinoneimine (NAPQI), acetaminophen-glutathione (acetaminophen-glut) and acetaminophen-glucuronide (acetaminophen-gluc) in mouse plasma, liver and kidney homogenates. Analytes were eluted by a binary gradient mobile phase composed of water (phase A) and methanol containing 0.1% formic acid (phase B) at a flow rate of 0.3 mL/min, which was performed on a CAPCELL PAK C18 MG II column. It took 3.2 min to detect three analytes in a single run. Quantification was carried out in positive mode combined with multiple reaction monitoring. The validation of the LC-MS/MS method consisted of specificity, linearity, precision, accuracy, protein precipitation recovery, matrix effect, dilution integrity and stability. The plasma and tissue homogenate calibration curves were linear over concentration ranges of 0.050-5.00, 0.050-5.00 and 0.100-40.0 µg/mL, with a lower limit of quantification of 0.050, 0.050, and 0.100 µg/mL for NAPQI, acetaminophen-glut and acetaminophen-gluc, respectively. The intra- and inter-run precision values were within 12.47% for NAPQI, 12.11% for acetaminophen-glut and 11.86% for acetaminophen-gluc at their lower limit of quantitation levels. The samples were stable under all tested conditions. This method was successfully applied to study the pharmacokinetics of NAPQI, acetaminophen-glut and acetaminophen-gluc in ICR mice following oral administration of 200 mg/kg of acetaminophen suspension.

Screening active components of modified Xiaoyao powder as NRF2 agonists.

Nuclear factor (erythroid-derived 2)-like 2 (NRF2) regulates antioxidant enzymes and phase II detoxifying enzymes, such as NAD(P)H: quinone oxidoreductase 1 (NQO1). Modified Xiaoyao powder (MXP) is most frequently used in the prevention and treatment of breast cancer in China. This study aimed to screen active components of MXP for antioxidant stress and chemoprevention, which depend on NRF2-NQO1 signalling pathway. A total of 25 monomeric compounds contained in MXP were screened using an antioxidant response element-luciferase reporter. The most potent antioxidant response element-luciferase inducers were chosen to further examine their effects on NRF2 and NQO1 in MCF-7 cells. These results were then confirmed by determining the oxidative stress levels and chemopreventive effect on inhibiting carcinogenesis transformation in NRF2 knockdown (NRF2KD ) and NRF2 wild-type MCF-10A cells. We found that quercetin, kaempferol, and atractylenolide II in MXP were potent NRF2 inducers, which could up-regulate the expression of NRF2 and its downstream enzymes NQO1. In addition, these components could decrease reduced oxidative stress and inhibit carcinogenesis transformation, which depended on NRF2-NQO1 pathway. In conclusion, NRF2-NQO1 pathway plays an essential role in mediating the activity of MXP and its active components, at least in part; some beneficial effects of MXP may be applicable to breast cancer chemoprevention. Our study firstly found MXP active components including quercetin, kaempferol, and atractylenolide II. Our results firstly demonstrate that NRF2-NQO1 pathway plays an essential role in mediating the activity of MXP and its active components in breast cancer chemoprevention. Our study firstly found that atractylenolide II is a novel NRF2 inducer.

UPLC-MS/MS method for the determination of tobacco-specific biomarker NNAL, tamoxifen and its main metabolites in rat plasma.

Cigarette smoke is known to interact with tamoxifen-metabolizing enzymes and transporters and potentially affect its treatment outcome. 4-(N-nitrosomethylamino)-1-(3-pyridyl)-1-butanol (NNAL) is an important metabolite of 4-(methylnitro-samino)-1-(3-pyridyl)-1-butanone (NNK) because it is frequently used as a biomarker to assess human smoke exposure. In order to study the potential pharmacokinetic interaction between cigarette smoke and tamoxifen in rats a UPLC-MS/MS method for the simultaneous determination of NNAL and tamoxifen along with its metabolites in rat plasma has been developed and validated. Analytes were extracted with methanol and separated on a HSS T3 column by a gradient elution with the mobile phase consisting of acetonitrile and water. The lower limits of quantitation ranged from 0.05 to 0.62 ng/mL. Precisions showed RSD <15.8% and accuracy in the range 80.6-116.0%. Mean analyte recoveries ranged from 76.9 to 108.4%. The method was successfully applied to study the effects of cigarette smoke condensate (CSC), NNK and benzo(a)pyrene pre-treatment on the pharmacokinetics of tamoxifen and its metabolites in rats. Significant effects of CSC, NNK, benzo(a)pyrene were observed on pharmacokinetics of tamoxifen and its metabolites. We also found that plasma NNAL levels are statistically significant correlated with plasma 4-hydroxy-tamoxifen and endoxifen.

Chinese herbal medicine for oesophageal cancer.

BACKGROUND: Oesophageal cancer is the seventh leading cause of cancer death worldwide. Traditional Chinese herbal medicine is sometimes used as an adjunct to radiotherapy or chemotherapy for this type of cancer. This review was first published in 2007 and updated in 2009; this 2016 update is the latest version of the review. OBJECTIVES: To assess the efficacy and possible adverse effects of the addition of Chinese herbal medicine to treatment with radiotherapy or chemotherapy for oesophageal cancer. SEARCH METHODS: We searched the Cochrane Upper Gastrointestinal and Pancreatic Diseases Group Trials Register, the Cochrane Library, MEDLINE, EMBASE, Allied and Complementary Medicine Database (AMED), China National Knowledge Infrastructure (CNKI), VIP database, Wanfang database and the Chinese Cochrane Centre Controlled Trials Register up to 1 October, 2015. We also searched databases of ongoing trials, the Internet and reference lists. SELECTION CRITERIA: Randomised controlled trials (RCTs) comparing the use of radiotherapy or chemotherapy with and without the addition of Chinese herbal medicine. DATA COLLECTION AND ANALYSIS: At least two review authors independently extracted data and assessed trial quality. MAIN RESULTS: We tried to contact the 142 study authors by telephone, and finally included nine studies with 490 participants. All included studies were conducted in China, and allocated advanced oesophageal cancer patients to radiotherapy or chemotherapy groups, with and without additional Chinese herbal medicine. Quality of life, short-term therapeutic effects, TCM symptoms and adverse events caused by radiotherapy or chemotherapy were reported in these studies. Overall, we considered the trials to be at unclear or high risk of bias.The quality of life measure was conducted before and after the intervention; our analysis showed a beneficial effect, both in number of participants experiencing an improvement (risk ratio (RR) 2.20, 95% confidence interval (CI) 1.42 to 3.39; 5 RCTs, 233 participants, change of performance status score ≥ 10) and number of participants experiencing a deterioration (RR 0.41, 95% CI 0.27 to 0.62; 6 RCTs, 287 participants, change of performance status score ≤ 10). We judged this to have low quality evidence, downgrading quality of evidence for risk of bias and imprecision, and upgrading quality of evidence for the large effect.For short-term therapeutic effects, the results suggest that traditional Chinese medicine (TCM) has a positive impact on improvement (complete response + partial response) (RR 1.17, 95% CI 1.02 to 1.35; 8 RCTs, 450 participants), moderate quality evidence and downgrading for risk of bias. There was no significant difference for progressive disease (RR 0.73, 95% CI 0.52 to 1.01; 8 RCTs, 450 participants), low quality evidence and downgrading for risk of bias and imprecision. Three studies assessed this outcome after four weeks or three months' follow-up, the remaining studies gave no detailed information for this outcome. TCM symptoms, which was similar to short-term therapeutic effects evaluated with TCM clinical criteria, was diagnosed in two studies of 88 people at the end of the intervention. The results suggest that TCM has a positive impact on both total effectiveness (RR 1.84, 95% CI 1.20 to 2.81) and ineffectiveness (RR 0.22, 95% CI 0.05 to 0.93); we judged the studies to have very low quality evidence, downgrading for risk of bias and imprecision.Nine studies reported a series of adverse events caused by radiotherapy or chemotherapy at the end of the intervention, including mucositis, radiation oesophagitis, arrest of bone marrow, gastrointestinal reactions, renal and hepatic impairment, white blood cell descent, neurotoxicity, cardiac toxicity and anaemia. For those containing multiple studies, we conducted a pooled analysis. As a result, TCM showed a significant effect on radiation oesophagitis (RR 0.66, 95% CI 0.47 to 0.94; 2 RCTs, 90 participants), gastrointestinal reactions (RR 0.54, 95% CI 0.36 to 0.81; 4 RCTs, 268 participants) and white blood cell descent (RR 0.60, 95% CI 0.44 to 0.83; 4 RCTs, 224 participants). The quality of evidence was low or very low, downgrading for risk of bias and imprecision. AUTHORS' CONCLUSIONS: We currently find no evidence to determine whether TCM is an effective treatment for oesophageal cancer. The effect of TCM on short-term therapeutic effects is uncertain. TCM probably has positive effects on quality of life and on some adverse events caused by radiotherapy or chemotherapy in advanced oesophageal cancer patients undergoing radiotherapy or chemotherapy. The results of the review need to be interpreted cautiously owing to overall low quality evidence. Future trials should be large and correctly designed to detect important clinical effects and minimise risk of bias.

Simultaneous determination of ginsenoside Rg1 , Re and notoginsenoside R1 in human plasma by LC-MS/MS and its application in a pharmacokinetic study in Chinese volunteers.

A rapid and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated for simultaneous quantification of ginsenosides Rg1 , Re and notoginsenoside R1 in human plasma. Chromatography was performed on Capcell Pak C18 MG II column using a binary gradient using mobile phase A (5 mm ammonium formate solution) and B (methanol, containing 5 mm ammonium formate) at a flow rate of 0.3 mL/min. The entire chromatographic run time was 3.2 min. Quantification was achieved using multiple reaction monitoring in positive mode using API 3000. This method was validated in terms of specificity, linearity, precision, accuracy, matrix effect and stability. The calibration curves were linear in the concentration range of 0.020-5.00 ng/mL for ginsenosides Rg1 , Re and notoginsenoside R1 . The lower limit of quantification (LLOQ) of this method was 0.020 ng/mL. The intra-run and inter-run precision values were within 12.31% for ginsenoside Rg1 , 14.13% for ginsenoside Re and 11.46% for notoginsenoside R1 at their LLOQ levels. The samples were stable under all tested conditions. This method was successfully applied to study the pharmacokinetics of ginsenoside Rg1 and notoginsenoside R1 in 24 healthy volunteers following oral administration of 200 mg Sanqi Tongshu Enteric-Pellets Capsule.

Comparisons of pharmacokinetics and NO-releasing of nitrofibriate and fenofibrate after oral administration in rats.

Nitrofibriate, a new compound of hypolipidemic, is modified based on fenofibrate. Both of them are used for prevention and treatment of cardiovascular diseases. In this study, an accurate and sensitive analytical method of reversed-phase high-performance liquid chromatography was developed to determine fenofibric acid, which is an active metabolite of both nitrofibriate and fenofibrate in rat plasma. This method was validated and successfully applied to pharmacokinetic study of nitrofibriate and fenofibrate after oral administration. The results suggested that the pharmacokinetic behavior of nitrofibriate followed a nonlinear process, while fenofibrate was linear, demonstrating that the two drugs were different in pharmacokinetic behaviors. Moreover, the effect of fenofibrate and nitrofibriate on releasing NO in rat serum was explored. This study showed that nitrofibriate, as a nitric oxide donor, could slowly release nitric oxide in vivo. This study provided a biopharmaceutical basis for further study of nitrofibriate.

[Advances in the research of pharmacogenomics of tamoxifen].

Tamoxifen (TAM) is the most common nonsteroidal antiestrogen agent, which has been widely used in the prevention of recurrence of estrogen or progesterone receptor-positive breast cancer in patients. It is metabolized by cytochrome P450 oxidases to its active metabolite (4-hydroxytamoxifen, 4-OH-TAM) and endoxifen (EDF), which played a critical role in the therapy. 4-OH-TAM and EDF have 30- to 100-fold more potency than TAM in the suppression of estrogen-dependent breast cancer cell proliferation. CYP3A4 and CYP2D6, as the key drug-metabolizing enzymes in those metabolic actions, are known to have several alleles. Genetic polymorphisms of CYP2D6 and CYP3A4 will influence the plasma concentrations of active TAM metabolites and clinical outcomes for breast cancer patients treated with TAM. The genetic polymorphisms of drug transporters, involved in the disposition of active TAM metabolites, also have the potential to influence the plasma concentrations of active TAM metabolites and clinical outcome for the treatment of breast cancer. In this review, we summarized the association of the genetic polymorphisms in the metabolic enzymes and transporters involved in the metabolism and disposition of TAM with the metabolite concentration, efficacy and adverse effects of TAM, which provides a fundamental reference for further pharmacogenomic study and clinical use of TAM.

[Transplacental transport mechanisms of drugs for transplacental treatment of fetal tachyarrhythmia of MDCKII/MDCKII-BCRP cell line].

To study the transport mechanisms of drugs for transplacental treatment of fetal tachyarrhythmia, MDCKII-BCRP and MDCKII cell models was used. MDCKII-BCRP and MDCKII cell monolayer model was used to investigate the bi-direction transport of sotalol, propranolol, propafenone, procainamide and flecainide. Drug concentrations were measured by HPLC-UV or chemiluminescence. The apparent permeability coefficient (P(app)), efflux rate (R(E)) and net efflux rate (R(net)) were calculated. Drugs with R(net) greater than 1.5 were further investigated using cellular accumulation experiments with or without a BCRP inhibitor. The R(net) of sotalol, propranolol, propafenone and procainamide were less than 1.5, while R(net) of flecainide with concentrations of 20 and 5 µmol x L(-1) were 1.6 and 1.9, respectively. The results showed that the transport of flecainide on MDCKII-BCRP cell monolayer could be mediated by BCRP; and the affinity increased when the concentration of flecainide decreased. Cellular accumulation experiments further suggested that accumulation of flecainide in MDCKII-BCRP cells was significantly lower than that in MDCKII cells in a concentration-dependent manner. BCRP inhibitor quercetin (50 µmol x L(-1)) significantly increased the accumulation of flecainide in MDCKII-BCRP cells (P < 0.05). Our preliminary data showed that flecainide but not sotalol, propranolol, propafenone or procainamide can be a substrate of BCRP. Thus the effect of flecainide may be affected by the BCRP in the maternal placental trophoblast membrane layer when treating fetal tachyarrhythmia.

[Determination of Desloratadine and Its Metabolite 3-OH Desloratadine in Human Plasma by LC-MS/MS].

OBJECTIVE: To develop a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous determination of desloratadine and its metabolite 3-OH desloratadine in human plasma. METHODS: 24 healthy male volunteers received a single oral dose of 5 mg desloratadine tablets in a randomized crossover bioequivalence study with two preparations of tablets. Serial plasma samples were taken and analyzed by the LC-MS/MS method. The pharmacokinetic parameters of the two preparations were calculated and compared statistically to evaluate their bioequivalence using Winnonlin 6. 3. RESULTS: The calibration curves of desloratadine and 3-OH desloratadine were both linear over the concentration range of 0. 050-6. 0 ng/mL, with intra-batch and inter-batch relative standard deviations less than 15%. The 90% confidence intervals (CIs) of peak concentration (Cmax) area under the curve (AUC)0t and AUC0-∞ of desloratadine and 3-OH desloratadine all resided within the bioequivalence limit 80%-125%. No significant difference in peak time (Tmax) was demonstrated between the two preparations. CONCLUSION: The LC-MS/MS method can be used for simultaneous determination of desloratadine and 3-OH desloratadine in human plasma, which has been successfully applied-to a bioequivalence study.

[Enhancers on the transmembrane transport of chlorogenic acid].

To investigate the influence of the difference enhancers on the transport mechanism of chlorogenic acid (CGA) across Caco-2 cells model, a RP-HPLC method was adopted to detect the concentrations of CGA. At the concentrations of 20 to 80 microg x mL(-1), the difference of absorption rate constants (K(a)) was not statistically significant. At the concentrations of 40 and 20 microg x mL(-1), the ratios of apparent permeability coefficients (P(app)) of the apical to basolateral and the basolateral to apical were 1.14 and 1.18, respectively. With the effect of enhancers K(a) and P(app) increased, the absorption half-life (T1/2) decreased. CGA passed through the Caco-2 cell membrane mainly by passive transport. It showed that monocarboxylic acid transporter (MCT) could be involved in the across membrane transport process of CGA. Borneol had no effect on the cell membrane transport processes. The order of increasing absorption of CGA caused by the enhancers was sodium lauryl sulphate > sodium taurocholate > carbomer.