Xin-an Wu

Simultaneous Determination of Metformin, Metoprolol and its Metabolites in Rat Plasma by LC–MS-MS: Application to Pharmacokinetic Interaction Study

A simple, rapid and sensitive liquid chromatography-tandem mass spectrometry (LC-MS-MS) method was developed and validated for the simultaneous quantitation of metformin (MTF), metoprolol (MET), α-hydroxymetoprolol (HMT) and O-desmethylmetoprolol (DMT) in rat plasma using paracetamol as an internal standard (IS), respectively. The sample preparation involved a protein-precipitation method with methanol after the addition of IS. The separation was performed on an Agilent HC-C18 column (4.6 × 250 mm, 5 µm) at a flow rate of 1.0 mL/min, using methanol-water containing 0.1% formic acid (39:61, v/v) as mobile phase, and total run time was 8.5 min. MS-MS detection was accomplished in multiple reaction monitoring mode with positive electrospray ionization. The monitored transitions were m/z 130.1 → 60.2 for MTF, m/z 268.2 → 116.1 for MET, m/z 284.2 → 116.1 for HMT, m/z 254.2 → 116.1 for DMT and m/z 152.3 → 110.1 for IS. The method was fully validated in terms of selectivity, linearity, accuracy, precision, stability, matrix effect and recovery over a concentration range of 19.53-40,000 ng/mL for MTF, 3.42-7,000 ng/mL for MET, 2.05-4,200 ng/mL for HMT and 1.95-4,000 ng/mL for DMT, respectively. The analytical method was successfully applied to drug interaction study of MTF and MET after oral administration of MTF and MET. Results suggested that the coadministration of MTF and MET results in a significant drug interaction in rat.

Effect of Yin-Zhi-Huang on up-regulation of Oatp2, Ntcp, and Mrp2 proteins in estrogen-induced rat cholestasis.

Abstract Context: Yin–Zhi–Huang (YZH), a prescription of traditional Chinese medicine, is widely used to treat neonatal jaundice or cholestasis. Objective: This study investigates the regulatory effect of YZH on the localization and expression of organic anion transporting polypeptides 2 (Oatp2), Na+-taurocholate co-transporting polypeptide (Ntcp), multidrug-resistance-associated protein 2 (Mrp2), and bile salt export pump (Bsep) in estrogen-induced cholestasis rats. Material and methods: Cholestasis model rats were induced via subcutaneous injection of estradiol benzoate (EB, 5 mg/kg/d) for 5 d. Other EB-induced rats were treated with saline (2 ml) or YZH (1.5 g/kg, two times a day) for 7, 14, and 21 d. The biochemical and pathologic examinations were performed. Moreover, the localization and expression of Oatp2, Ntcp, Mrp2, and Bsep were determined by immunohistochemisty and Western blotting, respectively. Results: YZH treatment could significantly decrease the serum total bile acids (TBA) (4.9 ± 0.6–2.8 ± 0.8) and direct bilirubin (DBIL) (2.6 ± 0.7–1.0 ± 0.1) levels, improve the histological disorganization, and, respectively, increase the expression of Oatp2 and Ntcp by 46% and 28% compared with saline-treated (p < 0.05) rats at 14 d. The expression of Mrp2 increased by 45% was observed in YZH treated compared with saline-treated (p < 0.05) rats at 7 d. However, there was a little change in the expression of Bsep (p > 0.05) after YZH treatment for 7, 14, and 21 d. Discussion and conclusion: In conclusion, the therapeutic effect of YZH to cholestasis could be attributed to the regulation of Oatp2, Ntcp, Mrp2, and Bsep.

Inhibitory effect of atenolol on urinary excretion of metformin via down-regulating multidrug and toxin extrusion protein 1 (rMate1) expression in the kidney of rats.

Renal tubular secretion is an important pathway for the elimination of many clinically used drugs. Metformin, a commonly prescribed first-line antidiabetic drug, is secreted primarily by the renal tubule. Many patients with type 2 diabetes mellitus (T2DM) receiving metformin may together be given selective β1 blockers (e.g., atenolol). Therefore, it is of great use to evaluate the effect of atenolol on metformin urinary excretion for exploring drug interactions and predicting the adverse effect of drugs. The aim of this study was to investigate the effect of atenolol on the pharmacokinetic of metformin and plasma lactate (LCA) level in rats, for high LCA is a serious adverse reaction of metformin after long-term metformin treatment. In this study, rats were treated with metformin alone or in combination with atenolol. Plasma, urine and tissue concentration of metformin was determined by HPLC method, while Western blotting and immunohistochemical analysis were used to evaluate the renal expression of rat organic cation transporter 2 (rOct2) and multidrug and toxin extrusion protein 1 (rMate1). The results showed that, after 7 days drug treatment, the AUC0 → t of metformin in atenolol and metformin co-administration group was significantly increased by 19.5% compared to that in metformin group, while the 24h cumulative urinary excretion of metformin was significantly decreased by 57.3%. In addition, atenolol treatment significantly decreased the renal expression of rMate1, but had no effect on rOct2 expression, renal blood perfusion and glomerular filtration. Moreover, plasma LCA level in atenolol and metformin co-administration group was significantly increased by 83.3% compared to that in metformin group after 60 days drug treatment. These results indicated that atenolol can inhibit urinary excretion of metformin via decreasing renal rMate1 expression, and long-term atenolol and metformin co-administration may induce potential lactic acidosis. Our results, for the first time, provided an important experimental evidence that rMate1 is the target of transporter-mediated drug interactions concerning metformin and atenolol.

Quantitative structure-activity relationship analysis of a series of human renal organic anion transporter inhibitors.

Organic anion transporters (OATs) have been proved to play important roles in the membrane transport of numerous potentially toxic xenobiotics, drugs, and endogenous metabolites. In general, OATs substrates can compete with one another for the transporter to mutually decrease renal secretion and thus delay the clearance and prolong the duration of action of each compound. Such interactions have the potential to bring about adverse outcomes for clinical cases. Therefore, it is very important to assess the molecular bioactivity to inhibit OATs during the development of new drugs and co‐administration. In this work, the relationships between 45 chemicals and their corresponding hOAT1 and hOAT3 inhibitory activities were analyzed. The quantitative structure–activity relationship (QSAR) model was developed by genetic algorithm and multiple linear regression method. The predictive power of the proposed model was strictly evaluated, and the applicability domain was also defined. The proposed models were robust and satisfactory and could provide a feasible and effective tool for hOAT1 or hOAT3 inhibitor screening.

Effect of hesperidin on the pharmacokinetics of CPT-11 and its active metabolite SN-38 by regulating hepatic Mrp2 in rats.

The usage of irinotecan hydrochloride (CPT‐11) chemotherapy is hindered by its dose‐limiting diarrhea which appears to be associated with the intestinal exposure to SN‐38, the active metabolite of CPT‐11. Hesperidin, a safe and natural food ingredient flavonoid, exhibits various biological properties. Accumulated evidence showed that the regulatory effect of hesperidin on the expression of Mrp2 in the liver may be one of the critical factors controlling the biliary excretion of SN‐38. This study examined the effect of hesperidin on the pharmacokinetics of CPT‐11 and SN‐38 as well as the regulatory effect on the hepatic expression of Mrp2. Compared with the control group, the AUC5‐t was increased to 115% of CPT‐11 and 122% of SN‐38; the CL was decreased to 87% for CPT‐11; the tissue concentration was increased in the liver, kidney and colon; and the accumulated biliary excretion was significantly decreased to 77% for CPT‐11 and 76% for SN‐38 in hesperidin‐treated rats. Furthermore, the expression of Mrp2 in the liver was significantly decreased to 37% in the hesperidin‐treated rats compared with that of the control group. These results indicate that oral administration of hesperidin significantly increased the AUC5‐t and reduced the clearance of CPT‐11 and SN‐38, possibly by decreasing the hepatic expression of Mrp2, and thus inhibiting the biliary excretion of CPT‐11 and SN‐38. The results from this present study suggest that hesperidin may reduce the exposure of CPT‐11 and SN‐38 in the intestine by reducing the amount of biliary excretion of CPT‐11 and SN‐38. Copyright

Development of a LC-MS/MS method for simultaneous determination of metoprolol and its metabolites, α-hydroxymetoprolol and O-desmethylmetoprolol, in rat plasma: application to the herb–drug interaction study of metoprolol and breviscapine

A simple, specific and sensitive LC-MS/MS method was developed and validated for the simultaneous determination of metoprolol (MET), α-hydroxymetoprolol (HMT) and O-desmethylmetoprolol (DMT) in rat plasma. The plasma samples were prepared by protein precipitation, then the separation of the analytes was performed on an Agilent HC-C18 column (4.6 × 250 mm, 5 µm) at a flow rate of 1.0 mL/min, and post-column splitting (1:4) was used to give optimal interface flow rates (0.2 mL/min) for MS detection; the total run time was 8.5 min. Mass spectrometric detection was achieved using a triple-quadrupole mass spectrometer equipped with an electrospray source interface in positive ionization mode. The method was fully validated in terms of selectivity, linearity, accuracy, precision, stability, matrix effect and recovery over a concentration range of 3.42-7000 ng/mL for MET, 2.05-4200 ng/mL for HMT and 1.95-4000 ng/mL for DMT. The analytical method was successfully applied to herb-drug interaction study of MET and breviscapine after administration of breviscapine (12.5 mg/kg) and MET (40 mg/kg). The results suggested that breviscapine have negligible effect on pharmacokinetics of MET in rats; the information may be beneficial for the application of breviscapine in combination with MET in clinical therapy.

The impact of drug transporters on adverse drug reaction

In this review, we have highlighted the adverse drug reaction mediated by transporters from two aspects: (1) competitive interactions between drug and drug/metabolite/endogenous substance mediated by transporters; (2) the expression/function change of transporter due to physiologic factors, disease, and drugs induction. It indicated that transporters exhibited a broad substrate specificity with a degree of overlap, which could change the pharmacokinetics of drugs and cause toxicity due to competition interactions among substrates. In addition, the expression and function of transporters were regulated by physiological conditions, pathological conditions, and drugs induction, which could cause adverse drug reaction and interindividual differences. Furthermore, one substrate was always medicated by several transporters and often subjected to metabolism by CYP enzymes, so we should be more aware of the increased plasma concentration of drugs caused by drug transporters as well as drug metabolizing enzymes synergistically, especially for drugs with narrow therapeutic window. In addition, the weightiness for one transporter to induce drugs plasma/tissue concentration change could be different in different condition. On the whole, transporters were corresponding with systemic/organs exposure of drug/metabolites/endogenous compounds. So understanding the expression and function in drug transporters will result in better strategies for optimal dosage regimen and reduce the risk for drug adverse reaction as well as adverse drug–drug interactions.

Extraction, separation and quantitative structure–retention relationship modeling of essential oils in three herbs

The essential oils extracted from three kinds of herbs were separated by a 5% phenylmethyl silicone (DB-5MS) bonded phase fused-silica capillary column and identified by MS. Seventy-four of the compounds identified were selected as origin data, and their chemical structure and gas chromatographic retention times (RT) were performed to build a quantitative structure-retention relationship model by genetic algorithm and multiple linear regressions analysis. The predictive ability of the model was verified by internal validation (leave-one-out, fivefold, cross-validation and Y-scrambling). As for external validation, the model was also applied to predict the gas chromatographic RT of the 14 volatile compounds not used for model development from essential oil of Radix angelicae sinensis. The applicability domain was checked by the leverage approach to verify prediction reliability. The results obtained using several validations indicated that the best quantitative structure-retention relationship model was robust and satisfactory, could provide a feasible and effective tool for predicting the gas chromatographic RT of volatile compounds and could be also applied to help in identifying the compound with the same gas chromatographic RT.

An integrated simultaneous distillation-extraction apparatus for the extraction of essential oils from herb materials and its application in Flos Magnoliae.

A large number of herb materials contain essential oils with extensive bioactivities. In this work, an integrated simultaneous distillation-extraction (ISDE) apparatus was developed. To demonstrate its feasibility, the performance of ISDE was evaluated for the extraction of essential oil from Flos Magnoliae and compared with conventional techniques including steam distillation (SD) and simultaneous distillation-extraction (SDE). According to the product yield, the time consumed and the composition of oil, the essential oils isolated by ISDE were better than that obtained by SD and similar to those obtained by SDE. ISDE was also better than SDE due to its simple operation and lower consumption of energy and organic solvent.

Hesperidin Alleviates Oxidative Stress and Upregulates the Multidrug Resistance Protein 2 in Isoniazid and Rifampicin-Induced Liver Injury in Rats

Isoniazid (INH) and rifampicin (RFP), two front‐line drugs used in tuberculosis therapy, may lead to seriously hepatotoxicity. The current study was carried out to investigate the hepatoprotective effects of hesperidin against INH‐ and RFP‐induced oxidative damage. The liver injury animal model of rats was induced by INH (75 mg/kg) and RFP (150 mg/kg) coadministration for 7 days, and hesperidin, at the dose of 50, 100, and 200 mg/kg, was orally administered to rats 2 h before INH and RFP administration. The biochemical and pathologic examinations were performed after rats were sacrificed. Moreover, the serum and liver glutathione (GSH), glutathione disulfide (GSSG), malondialdehyde (MDA), GSH peroxidase, and GSSG reductase were determined by test kits, and the expression of multidrug resistance proteins 2 (Mrp2) was determined by Western blotting and immunohistochemistry. The results showed that hesperidin significantly alleviated liver injury as indicated by the decreased levels of ALT, AST, bilirubin, total bile acid, and glutathione peroxidase and the increased levels of the GSH/GSSG ratio and the expression of Mrp2. Moreover, hesperidin could effectively reduce the pathological tissue damage. These results indicate that hesperidin can attenuate INH‐ and RFP‐induced oxidative damage, and the underlying mechanism may have correlation with its effect on the upregulation of Mrp2.