Guo-qiang Zhang

Synergistic penetration of ethosomes and lipophilic prodrug on the transdermal delivery of acyclovir

The aim of this study was to investigate the lipophilic prodrug as a means of promoting acyclovir (ACV) that exhibited biphasic insolubility into the ethosomes for optimum skin delivery. Acyclovir Palmitate (ACV-C16) was synthesized as the lipophilic prodrug of ACV. The ethosomal system and the liposomal system bearing ACV or ACV-C16 were prepared, respectively. The systems were characterized for shape, zeta potential value, particle size, and entrapment efficiency. Franz diffusion cells and confocal laser scanning microscopy were used for the percutaneous absorption studies. The results showed that the entrapment efficiency of ACV-C16 ethosomes (87.75%) were much higher than that of ACV ethosomes (39.13%). The quantity of drug in the skin from ACV-C16 ethosomes at the end of the 24 h transdermal experiment (622.89 μg/cm2) was 5.30 and 3.43 times higher than that from ACV-C16 hydroalcoholic solution and ACV ethosomes, respectively. This study indicated that the binary combination of the lipophilic prodrug ACV-C16 and the ethosomes synergistically enhanced ACV absorption into the skin.

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.

Development of a dynamic multiple reaction monitoring method for determination of digoxin and six active components of Ginkgo biloba leaf extract in rat plasma

A new liquid chromatography-tandem mass spectrometry (LC-MS/MS) method by using dynamic multiple reaction monitoring (DMRM) has been developed and validated for the simultaneous determination of digoxin (DGX) and six main components of Ginkgo biloba leaf extract (GBE) in rat plasma. Comparing with the conventional multiple reaction monitoring (MRM), DMRM dramatically decreases the number of concurrent MRM transitions, and significantly extended the dwell time, which provided much higher sensitivity and reproducibility than MRM when complex multi-component samples were quantified. The plasma samples were protein precipitated with methanol, the detection was accomplished with electro-spray ionization (ESI) as the ion source operating in the negative ionization mode, with methanol and water as mobile phase, and with an Agilent Zorbax eclipse plus C18 column (4.6 × 100 mm, 3.5 μm) as the analytical column. The total run time was 12.0 min. The validation of the method was implemented including specificity, linearity, accuracy, precision, recovery, matrix effect and stability. This method was successfully applied to the herb-drug pharmacokinetic interaction study of DGX combined with GBE after oral administration to rats. The result indicated that co-administration of GBE and DGX significantly influenced the pharmacokinetics of DGX when compared to that of single DGX-treated rats.

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.

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.

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.

Anticolitis activity of Chinese herbal formula yupingfeng powder via regulating colonic enterochromaffin cells and serotonin.

Objective: To investigate whether traditional Chinese herbal formula Yupingfeng (YPF) powder has an anti-inflammatory effect on colonic inflammation, and to explore the mechanism involved. Materials and Methods: YPF powder was orally administrated to trinitrobenzene sulfonic acid (TNBS)-induced colitis mice at the dose of 3, 6, and 12 g/kg/d for 7 consecutive days. Body weight, stool consistency, histopathological score, and myeloperoxidase (MPO) activity were tested to evaluate the effect of YPF powder on colonic inflammation while colonic enterochromaffin (EC) cell density and serotonin 5-hydroxytryptamine (5-HT) content were investigated to identify the effect of YPF powder on colonic 5-HT availability. Results: The results showed that the body weight of colitis mice was markedly decreased by 10, 12, 14, and 17% at 1, 3, 5, and 7 days (P < 0.05), whereas stool consistency score (3.6 vs. 0.4, P < 0.05), histopathological score (3.6 vs. 0.3, P < 0.05), and MPO activity (2.7 vs. 0.1, P < 0.05) in colitis mice were significantly increased compared to that of the normal mice; YPF powder treatment dose-dependently increased the body weight (7–13% increase) and decreased the stool consistency score (0.4–1.4 decrease), histopathological score (0.2–0.7 decrease), and MPO activity (0.1–0.9 decrease) in colitis mice. Colonic EC cell density (70% increase) and 5-HT content (40% increase) were markedly increased in colitis mice (P < 0.05), YPF powder treatment dose-dependently reduced EC cell density (20–50% decrease), and 5-HT content (5–27% decrease) in colitis mice. Conclusion: The findings demonstrate that the anti-inflammatory effect of YPF powder on TNBS - induced colitis may be mediated via reducing EC cell hyperplasia and 5-HT content. The important role of YPF powder in regulating colonic EC cell number and 5-HT content may provide an alternative therapy for colonic inflammation.