Herb-Drug Interaction: Application of a UPLC-MS/MS Method to Determine the Effect of Polygonum capitatum Extract on the Tissue Distribution and Excretion of Levofloxacin in Rats

Polygonum capitatum has unique curative effects on the urinary system. In fact, many Polygonum capitatum-based preparations are currently used in the clinic. In China, the combination of levofloxacin (LVFX) with a Chinese herbal preparation derived from Polygonum capitatum has been used for the clinical treatment of urinary system diseases, which can improve the curative effects and reduce the side effects of LVFX. However, the herb-drug interaction (HDI) between these drugs has not been reported and the effect of Polygonum capitatum on the in vivo process of LVFX is unclear. In this article, a sensitive ultraperformance liquid chromatography-tandem mass spectroscopy (UPLC-MS/MS) method was developed to evaluate the effects of the combined application of LVFX and the Polygonum capitatum extract on tissue distribution and excretion. Thereafter, the method was validated for selectivity, accuracy, precision, linearity, lower limit of quantification (LLOQ), dilution integrity, recovery, and matrix effect. Based on tissue distribution, LVFX could diffuse into all of the tested tissues, with significant differences in the content of each tissue between the coadministration group and single administration group. At 48 h after the combination was orally administered, the urinary cumulative excretion of LVFX decreased from 20.69% to 11.84% while its fecal cumulative excretion decreased from 26.08% to 13.28%. Our results suggest that a drug interaction exists between the two drugs in the process of distribution and excretion. This study provides important experimental evidence for further studies on the clinical efficacy and mechanism of the Polygonum capitatum extract and LVFX.

Quantification of Urinary Phenyl-γ-Valerolactones and Related Valeric Acids in Human Urine on Consumption of Apples

Flavan-3-ols are dietary bioactive molecules that have beneficial effects on human health and reduce the risk of various diseases. Monomeric flavan-3-ols are rapidly absorbed in the small intestine and released in the blood stream as phase II conjugates. Polymeric flavan-3-ols are extensively metabolized by colonic gut microbiota into phenyl-γ-valerolactones and their related phenylvaleric acids. These molecules are the main circulating metabolites in humans after the ingestion of flavan-3-ol rich-products; nevertheless, they have received less attention and their role is not understood yet. Here, we describe the quantification of 8 phenyl-γ-valerolactones and 3 phenylvaleric acids in the urine of 11 subjects on consumption of apples by using UHPLC-ESI-Triple Quad-MS with pure reference compounds. Phenyl-γ-valerolactones, mainly as sulfate and glucuronic acid conjugates, reached maximum excretion between 6 and 12 after apple consumption, with a decline thereafter. Significant differences were detected in the cumulative excretion rates within subjects and in the ratio of dihydroxyphenyl-γ-valerolactone sulfate to glucuronide conjugates. This work observed for the first time the presence of two distinct metabotypes with regards to the excretion of phenyl-γ-valerolactone phase II conjugates.

Comparative Study on Excretive Characterization of Main Components in Herb Pair Notoginseng-Safflower and Single Herbs by LC–MS/MS

The herbal medicine combination of notoginseng-safflower has been commonly used clinically for the prevention and treatment of cardiovascular diseases. A reliable liquid chromatography-tandem mass spectrometry (LC–MS/MS) method was developed for simultaneous determination of six bioactive components (hydroxysafflor yellow A, notoginsenoide R1, ginsenoside Rb1, Re, Rd, and Rg1) in rat urine and feces after oral administration of notoginseng total saponins (NS), safflower total flavonoids (SF), and the combination of NS and SF (CNS). The chromatographic separation was achieved on a Waters HSS T3 column under gradient elution with acetonitrile and water containing formic acid as the mobile phase. The calibration curves were linear, with correlation coefficient (r) > 0.99 for six components. The intra- and interday precision (RSD) and accuracy (RE) of QC samples were within −14.9% and 14.9%, respectively. The method was successfully applied to study of the urinary and fecal excretion of six bioactive constituents following oral administration of NS, SF, and CNS in rats. Compared to the single herb, the cumulative excretion ratios of six constituents were decreased in the herbal combination. The study indicated that the combination of notoginseng and safflower could reduce the renal and fecal excretion of the major bioactive constituents and promote their absorption in rats.

Pharmacokinetics and Excretion of 14C-Labeled Polyethylene Glycol (60 kDa) in Rats

Introduction: Although there is no evidence for PEG-related safety issues with PEGylated proteins in the clinic, questions relating to the pharmacokinetics including disposition and excretion of PEG are being raised more frequently by health authorities nowadays, particularly for PEGylated proteins used chronically and/or in the pediatric population (http://www.ema.europa.eu/docs/en_GB/document_library/Scientific_guideline/2012/11/WC500135123.pdf).BAY 94-9027, a B-domain–deleted recombinant FVIII with a 60-kDa branched PEG molecule attached via a maleimide linker to an amino acid using site-specific PEGylation, is in clinical development for acute and prophylactic intravenous treatment of hemophilia A. The objective of this study was to investigate the pharmacokinetics and excretion of radioactivity (unchanged compound and radioactive metabolites) after single intravenous administration of 14C-labeled BAY 1025662 (cysteine linker-[60-kDa] PEG part of BAY 94-9027 with the 14C label covalently integrated in the linker) in male Wistar rats. Methods: The administered dose was 11 mg/kg body weight related to BAY 1025662 (approximated human lifetime dose of PEG 60 kDa resulting from treatment with BAY 94-9027). The concentrations and amounts of radioactivity in urine, feces, blood, plasma, and selected organs and tissues were investigated in order to determine the excretion via urine and feces, and the pharmacokinetics of total radioactivity and radioactive residues in the animal body. Results: After single intravenous administration of 14C-BAY 1025662 to rats, a fast initial elimination of 14C radioactivity was observed; 63.2% of administered radioactivity was excreted within the first 24 hours (51.4% in urine, 11.8% in feces). Up to day 7, 75.6% of administered radioactivity was excreted predominantly via urine. The balance/recovery of radioactivity on day 7 amounted to 99.0% in relation to the administered radioactive dose. The radioactive residue in the animals amounted to 23.4% of administered dose. The majority of the residual radioactivity was recovered in the carcass and skin, followed by liver and kidneys. The excretion of radioactivity continued at steadily decreasing levels until the end of the study. The daily radioactivity excretion decreased from 2.1% at 72 hours to 0.013% of dose at 6 months after administration of 14C-BAY 1025662. The cumulative excretion of radioactivity via urine and feces was calculated (partly interpolated) to 92.2% of the administered radioactive dose by the end of the experiment on day 168 (74.5% via urine, 17.4% via feces, and 0.294% recovered in the cage wash). The radioactivity was continuously albeit slowly eliminated from the investigated organs and tissues. The elimination half-life of radioactivity was 26 and 23 days in blood and plasma, respectively. The corresponding elimination half-lives of radioactivity were 35, 41, and 31 days in the liver, carcass, and skin, respectively. Radioactivity elimination from kidneys was biphasic with a terminal half-life of 92 days. The radioactive residues in the animals excluding the gastrointestinal tract decreased during the study from 22.5% on day 7 to 1.79% of dose at the end of the study on day 168. There was no indication for any retention or irreversible binding of radioactivity in the animal body. The total recovery of radioactivity (cumulative excretion plus residues in the animals) was 94% in relation to the administered dose at the end of the experiment on day 168. Conclusions: In this study, nearly complete excretion of the 60-kDa PEG molecule (measured as total radioactivity) could be observed, with a fast initial elimination in the first few days and a subsequent considerably slower process until the end of the observation period (6 months). These results are in agreement with recently proposed fast and slow processes for the renal excretion of large PEG and PEG proteins (Baumann, A. et al. Drug Discov Today. 2014:[Epub ahead of print, http://dx.doi.org/10.1016/j.drudis.2014.06.002]). Disclosures Baumann: Bayer Pharma AG: Employment. Schwarz:Bayer Pharma AG: Employment. Seidel:Bayer Pharma AG: Employment. Hucke:Bayer Pharma AG: Employment. Steinke:Bayer Pharma AG: Employment. Buehner:Bayer Pharma AG: Employment.

Simultaneous Determination of Oxyresveratrol and Resveratrol in Rat Bile and Urine by HPLC after Oral Administration of Smilax china Extract

Oxyresveratrol ( trans-2,4,3′,5′-tetrahydroxystilbene, OXY) and resveratrol ( trans-3,5,4′-trihydroxystilbene, RES) are the two most important constituents of the traditional Chinese medicine Smilax china. A reversed-phase high-performance liquid chromatographic method was developed to determine OXY and RES in rat bile and urine after oral administration of Smilax china extract. The biological samples were analyzed by HPLC on Aglient Zorbax SB-C18 column (250 × 4.6 mm, 5 μm) at a wavelength 320 nm and at a flow rate of 1.0 mL/min. The method was accurate and reproducible for determination. The cumulative excretion of OXY and RES was 0.29% and 0.97% in bile samples, 0.84% and 0.65% in urine samples, respectively.

Urinary Excretion and Bactericidal Activities of Gemifloxacin and Ofloxacin after a Single Oral Dose in Healthy Volunteers

ABSTRACT In a randomized crossover study, 16 volunteers (8 men, 8 women) received single oral doses of 320 mg of gemifloxacin and 400 mg of ofloxacin on two separate occasions in the fasting state to assess the urinary excretion and urinary bactericidal titers (UBTs) at intervals for up to 144 h. Ofloxacin showed higher concentrations in urine compared with those of gemifloxacin. The median (range) cumulative excretion of gemifloxacin was 29.7% (8.4 to 48.7%) of the parent drug administered, and median (range) cumulative excretion of ofloxacin was 84.3% (46.5 to 95.2%) of the parent drug administered. The UBTs, i.e., the highest twofold dilutions (with antibiotic-free urine as the diluent) of urine that were still bactericidal, were determined for a reference strain and nine uropathogens for which the MICs of gemifloxacin and ofloxacin were as follows:Escherichia coli ATCC 25922, 0.016 and 0.06 μg/ml, respectively; Klebsiella pneumoniae, 0.03 and 0.06 μg/ml, respectively; Proteus mirabilis, 0.125 and 0.125 μg/ml, respectively; Escherichia coli, 0.06 and 0.5 μg/ml, respectively; Pseudomonas aeruginosa, 1 and 4 μg/ml, respectively; Staphylococcus aureus, 0.008 and 0.25 μg/ml, respectively; Enterococcus faecalis, 0.06 and 2 μg/ml, respectively;Staphylococcus aureus, 0.25 and 4 μg/ml, respectively;Enterococcus faecalis, 0.5 and 32 μg/ml, respectively; and Staphylococcus aureus, 2 and 32 μg/ml, respectively. Generally, the UBTs for gram-positive uropathogens were higher for gemifloxacin than for ofloxacin and the UBTs for gram-negative uropathogens were higher for ofloxacin than for gemifloxacin. According to the UBTs, ofloxacin-resistant uropathogens (MICs, ≥4 mg/liter) should also be considered gemifloxacin resistant. Although clinical trials have shown that gemifloxacin is effective for the treatment of uncomplicated urinary tract infections, whether an oral dosage of 320 mg of gemifloxacin once daily is also adequate for the treatment of complicated urinary tract infections has yet to be confirmed.

Ntau;-methylhistidine excretion is a valid index of myofibrillar protein breakdown in the guineapig (Cavia porcellus)

The recovery of radioactivity in the urine of guineapigs following a bolus intravenous dose of chromatographically pure 14C-Nτ-methylhistidine was measured in order to test whether the excretion of Nτ-methylhistidine (Nτ-MH) is a valid index of myofibrillar protein breakdown in these animals. Four male and four female guineapigs were dosed and after 7 days, 91.65 ± 2.82% and 3.58 ± 0.91% of injected radioactivity was recovered in the excreta and tissues, respectively. The average total recovery of 95.2 ± 3.0% was not significantly different from 100%. Male guineapigs excreted the radioactivity more slowly than females (70% of the dose excreted within 74 h vs 39 h, respectively) but cumulative excretion at 7 days was the same for each sex. Chromatographic analysis of the urine showed almost all of the radioactivity to be associated with a single peak corresponding to Nτ-MH, indicating a lack of significant metabolism. These data show that although the clearance of 14C-Nτ-MH is slower than in rats or humans the urinary excretion of Nτ-MH is a valid index for myofibrillar protein degradation in the guineapig.

Metabolic capacity and interindividual variation in toxicokinetics of styrene in volunteers

The aim of the present study was to assess the interindividual variation in styrene toxicokinetics and to correlate this variation with the individual metabolic capacity for cytochromeP450 (CYP), CYP2E1, CYP1A2 and CYP2D6. Twenty male volunteers were exposed on separate occasions to 104±3 and 360 ± 20 mg/m3 of styrene for 1 h while performing 50 W physical exercise on a bicycle ergometer. Styrene concentrations in blood and mandelic (MA) and phenylglyoxylic acid (PGA) in urine were measured. The metabolic capacity was assessed by phenotyping with chlorzoxazone (CYP2El), caffeine (CYP1A2), dextromethorphan (CYP2D6) and antipyrine (CYP450). In addition, for the main styrene-metabolising enzyme, CYP2E1, genotyping for the genetic polymorphisms of the gene was performed. The average pulmonary retention of styrene was 62 ± 7% at both exposure concentrations, and the 24-h excretion of MA and PGA accounted for 58% of the dose at both concentrations. The interindividual variation in styrene kinetics ranged from 19% for the terminal half-life (t1/2,β) of styrene to 41% for the cumulative excretion of MA and PGA. However, no correlation between the apparent blood clearance of styrene (CLapp), t1/2,β of styrene or excretion of MA and PGA on one hand, and the individual metabolic capacity on the other hand was found. Although other explanations cannot be excluded, this lack of correlation might be due to the high apparent blood clearance (1.4 1/ min) of styrene, indicating that styrene metabolism is liver–blood-flow-dependent.