肾脏转运体及其研究方法

肾脏是机体重要器官之一,主要承担着体内代谢产物、药物以及毒物等物质的排泄。因此明确各物质在肾脏排泄机制有利于提高药物的安全性,避免不良反应,可为指导临床合理用药提供理论依据。本文介绍了肾脏中介导药物分泌与重吸收的转运体,阐述了通过体内、体外方法预测药物经肾脏转运体在肾脏的转运以及排泄机制。此外,还概括了研究肾脏转运体的主要研究方法,为基础以及临床实验提供参考。     

Analytical method for detection and quantification of new emerging drug etaqualone in human blood and urine by gas chromatography tandem mass spectrometry

Analytical procedure for detection and quantification of etaqualone in human blood and urine using GC–MS/MS was established and applied to authentic human samples obtained from volunteers. A liquid–liquid extraction method was employed. Each 1.0 mL of blood or urine was alkalized and extracted with diethyl ether. The solvent layer was evaporated to dryness and reconstituted with methanol then analyzed by GC–MS/MS. linear relationships within the concentration range of 1–100 ng/mL were obtained in calibrators for both blood and urine, demonstrating correlation coefficients values being>0.999. For blood and urine samples, the intra-day assay precision and accuracy values are each less than 3.65%, 7.13%, and 6.02%, 9.12%; those values of the inter-day assay are each less than 1.82%, 6.74%, and 3.99%, 7.41%. The extraction recovery rates for etaqualone ranged from 98.7% to 106%. The lower limit of quantifications was 1.0 ng/mL in both blood and urine. Stabilities of etaqualone in blood and urine were satisfactory under various temperatures within 15 days. 8.51 and 2.06 ng/mL of etaqualone in blood and urine were detected at 4 h later oral ingestion; 6.91 and 3.94 ng/mL of etaqualone were also detected 30 min and 2 h later smoking from blood and urine.     

Tributyltin-binding protein type 1 has a distinctive lipocalin-like structure and is involved in the excretion of tributyltin in Japanese flounder, Paralichthys olivaceus

Tributyltin-binding protein type 1 (TBT-bp1) is a newly discovered protein that binds with TBT in the blood of the Japanese flounder, Paralichthys olivaceus. We determined the genomic sequence of TBT-bp1 and found that this protein has a conserved exon–intron structure that is common to the lipocalin protein family. The secondary and tertiary structures of TBT-bp1, predicted from amino acid sequence, included at least two α-helices and eight β-sheets that are conserved in all lipocalins and form a barrel structure that may bind with ligands. Analysis of the gene structure, secondary structure, and tertiary structure demonstrated that TBT-bp1 could be classified as a lipocalin. A homology search revealed the presence of TBT-bp1-like proteins in eight species of teleost. When flounder were injected intraperitoneally with TBT-d27 at 11.6 μg/fish, TBT-d27 was detected in the blood and in the skin mucus. The concentration of TBT-d27 in mucus was approximately 1/100 of that in the serum. Western blotting analysis revealed that TBT-bp1 was present in the skin mucus. These results suggest that TBT-bp1 in Japanese flounder binds with TBT and is excreted from the body via the mucus.     

The metabolism and disposition of GSK2140944 in healthy human subjects

1.?GSK2140944 is a novel bacterial topoisomerase inhibitor in development for the treatment of bacterial infections. The metabolism and disposition in healthy human subjects was investigated.

2.?Six male subjects received [¹⁴C] GSK2140944 orally (2000?mg) and as a single 2-hour i.v. infusion (1000?mg). Urinary elimination (59%) was major by the i.v. route, whereas fecal elimination (53%) pre-dominated via the oral route. Accelerator mass spectrometry (AMS) was used for the analysis of plasma and bile samples due to the low level of radioactivity in samples (low specific activity of the doses). Unchanged GSK2140944 was the predominant circulating component (>60% DRM), with the main circulating metabolite M4 formed by oxidation of the triazaacenaphthylene moiety representing 10.8% (considered major) and 8.6% drug-related material by the oral and i.v. route, respectively. Approximately 50% of the oral dose was absorbed and eliminated mainly as unchanged GSK2140944 in urine (～20% of dose). Elimination via metabolism (～13% of dose) was relatively minor. The facile oxidation of GSK2140944 to metabolite M4 was believed to be a result of activation by adjacent electron withdrawing groups.

3.?This study demonstrates the use of AMS to overcome radioprofiling challenges presented by low specific activity resulted from high doses administration.     

羟基红花黄色素A脂质载体及水溶液在大鼠体内的代谢、排泄、生物利用度研究

目的：研究不同的羟基红花黄色素A（HSYA）剂型对HSYA代谢、排泄、生物利用度的影响。方法：大鼠灌胃给予HSYA脂质制剂和水溶液,采用HPLC及LC-MS检测血浆、胆汁、粪便、尿液样品。结果：大鼠灌胃给予HSYA脂质制剂和水溶液后,在大鼠胆汁中均发现HSYA及其II相代谢产物;HSYA原药的质荷比为611,而两个II相代谢产物的质荷比分别为918和691,结合酶降解实验表明这两个代谢产物分别为HSYA的谷胱甘肽结合物和硫酸酯结合物。但是同水溶液相比,HSYA脂质制剂显著性降低了HSYA及其II相代谢产物从胆汁的排泄量。大鼠灌胃给予HSYA脂质制剂后,HSYA原药从胆汁、粪便、尿液中24h的累积排泄量分别为（0.05±0.03）%、（8.80±2.30）%、（37.99±17.50）%,其cmax、AUC0-8h分别为2.79μg·mL^-1、402.51μg·min·mL^-1;而大鼠灌胃给予HSYA水溶液后,HSYA原药从胆汁、粪便、尿液中24h的累积排泄量分别为（0.32±0.22）%、（44.66±8.00）%、（5.58±1.30）%,其cmax、AUC0-8h分别为0.08μg·mL^-1、10.73μg·min·mL^-1。结论：实验结果表明脂质制剂可能不会改变HSYA的代谢机制,但是显著性降低了HSYA从粪便和胆汁的排泄量,提高了其生物利用度。     

Pharmacokinetics and Excretion Studies on CDRI-85/92, an Antiulcer Proton Pump Inhibitor

CDRI 85/92 is an antiulcer pharmacophore and a proton pump inhibitor, which is in an advanced stage of preclinical trials. In view of its importance, pharmacokinetic and excretion were studied in Sprague Dawley rats after administering 20 mg/kg oral and intravenous doses. The compound was detectable in the serum samples as early as 5 min post-oral administration. The compound was eliminated slowly from serum with an elimination half-life of 2.1 h. Following the 20 mg/kg oral dose, maximum serum concentration (C(max)) was found to be 469.28 ± 45.52 ng/ml after 1.0 h. Based on AUC values, the absolute bioavailability of the CDRI 85/92 was 70.5% after oral administration. It was found to be excreted in urine (~15% of the dose) in intravenously treated (bile duct cannulated as well as noncannulated) rats, whereas bile and feces depicted insignificant levels of the compound.     

Sex dependent pharmacokinetics,tissue distribution and excretion of peimine and peiminine in rats assessed by liquid chromatography–tandem mass spectrometry

Ethnopharmacological relevance

Fritillaria thunbergii Miq. has been traditionally used in China as antitussive and expectorant herbs, and newly used in the clinical treatment of leukemia in recent years.

Aim

To investigate whether gender exerted a significant influence on the pharmacokinetics, tissue distribution and excretion of peimine and peiminine in Sprague-Dawley rats who were given a single oral administration of 4.25 g/kg Fritillaria thunbergii Miq. extract.

Materials and methods

Sprague-Dawley rats were assigned into two groups based on the gender and orally administered 4.25 g/kg Fritillaria thunbergii Miq. extract for each individual pharmacokinetics, tissue distribution and excretion study.

Results

Compared with female rats, peimine and peiminine were eliminated slowly from male rat plasma, and significant gender-related differences were observed in the pharmacokinetic parameters. Drug blood and tissue levels in male rats were significantly higher than the female counterparts except for several tissues, such as fat, muscle and skin. Gender also exerted a significant influence on the urine excretion but such effect was not observed in the feces excretion study.

Conclusions

Gender exerted a significant influence on the pharmacokinetics, tissue distribution and urine excretion of peimine and peiminine. It is assumed that the sex-associated differences of peimine and peiminine in rats might be mainly result from sex-dependent expression and activity of drug metabolism enzymes and P-glycoprotein.     

The effect and fate of water-soluble carbon nanodots in maize (Zea mays L.)

In this study, the toxicity of water-soluble carbon nanodots (C-dots) to maize (Zea mays L.) and their uptake and transport in plants were investigated. After exposed in sand matrix amended with 0–2000?mg/L C-dots for 4 weeks, we found that the phytotoxicity of C-dots was concentration-dependent. C-dots at 250 and 500?mg/L showed no toxicity to maize. However, 1000 and 2000?mg/L C-dots significantly reduced the fresh weight of root by 57% and 68%, and decreased the shoot fresh weight by 38% and 72%, respectively. Moreover, in maize roots, the exposure of C-dots at 2000?mg/L significantly increased the H₂O₂ content and lipid peroxidation (6.5 and 1.65 times higher, respectively), as well as, the antioxidant enzymes activities, up to 2, 1.5, 1.9 and 1.9 times higher for catalase, ascorbate peroxidase, guaiacol peroxidase and superoxide dismutase, respectively. On the other hand, C-dots were observed in detached root-cap cells, cortex and vascular bundle of roots and mesophyll cells of leaves through fluorescence microscopy analysis, suggesting that C-dots were absorbed and translocated systemically in maize. Remarkably, a certain amount of C-dots were excreted out from leaf blade. To our knowledge, this is the first study combined phenotypic observation with physiologic responses and bioaccumulation and translocation analysis of C-dots to investigate their effect and fate in maize.     

Biological characteristics of lactosaminated N-succinyl-chitosan as a liver-specific drug carrier in mice

Lactosaminated N-succinyl-chitosan (Lac-Suc) was prepared by reductive amination of N-succinyl-chitosan (Suc) and lactose using sodium cyanoborohydride. Six-day reaction using lactose (12.8-fold (w/w)) yielded Lac-Suc with lactosamination degree of 30% (mol/sugar unit). Fluorescein thiocarbamyl-Lac-Suc (Lac-Suc-FTC) was prepared by labeling Lac-Suc with fluorescein isothiocyanate. Lac-Suc-FTC was injected intravenously at a dose of either 1 (high dose) or 0.2 (low dose) mg/mouse. At both doses, Lac-Suc-FTC initially underwent fast hepatic clearance, showed maximum liver localization at 8 h, and the amounts localized there were maintained even at 48 h post-injection. Very slow excretion into feces and urine was observed. The ratio of liver AUC_{0–48 h} to plasma AUC_{0–48 h} at low dose was three times higher than that at high dose. On the other hand, the Suc derivative, Gal-Suc, obtained by reductive amination of Suc/galactose showed very little distribution to the liver similarly to Suc itself. Further, since the liver uptake of Lac-Suc-FTC was inhibited by asialofetuin, it was suggested that the liver distribution of Lac-Suc should be concerned with asialoglycoprotein receptor. Thus, Lac-Suc was found available as a carrier exhibiting a high affinity to and long retention in the liver.