The simultaneous separation and determination of six flavonoids and troxerutin in rat urine and chicken plasma by reversed-phase high-performance liquid chromatography with ultraviolet-visible detection.

The method of high-performance liquid chromatography (HPLC) with UV-vis detection was used and validated for the simultaneous determination of six flavonoids (puerarin, rutin, morin, luteolin, quercetin, kaempferol) and troxerutin in rat urine and chicken plasma. Chromatographic separation was performed using a VP-ODS column (150 mm x 4.6 mm, 5.0 microm) maintained at 35.0 degrees C. The mobile phase was a mixture of water, methanol and acetic acid (57:43:1, v/v/v, pH 3.0) at the flow rate of 0.8 mL/min. Six flavonoids and troxerutin were analyzed simultaneously with good separation. On optimum conditions, calibration curves were found to be linear with the ranges of 0.10-70.00 microg/mL (puerarin, rutin, morin, luteolin, quercetin, kaempferol) and 0.50-350.00 microg/mL (troxerutin). The detection limits were 0.010-0.050 microg/mL. The method was validated for accuracy and precision, and it was successfully applied to determine drug concentrations in rat urine and chicken plasma samples from rat and chicken that had been orally administered with six flavonoids and troxerutin.

Liquid chromatography/tandem mass spectrometry assay for the quantification of troxerutin in human plasma.

A simple, rapid, sensitive and specific liquid chromatography/tandem mass spectrometry method was developed and validated to quantify troxerutin in human plasma. The analyte and rutin, used as the internal standard, were analyzed on a Phenomenex Synergi Fusion RP column interfaced with a triple-quadrupole tandem mass spectrometer using positive electrospray ionization. Acetonitrile/water (20:80 v/v) was used as the isocratic mobile phase, with 0.1% formic acid in water. A simple sample preparation method of protein precipitation with perchloric acid was employed. The assay was linear over the concentration range 31.25-4000 pg/mL. Correlation coefficients generated by linear regression with a 1/x(2) weighting factor ranged from 0.9991 to 0.9996. The intra- and inter-day precision over the entire concentration range were less than 12.28%. The method was successfully applied to a pharmacokinetic study after oral administration of a 300 mg troxerutin drop pill to 18 healthy volunteers.

A phase I study of monohydroxyethylrutoside in healthy volunteers.

The flavonol monohydroxyethylrutoside (monoHER) has demonstrated protection against doxorubicin-induced cardiotoxicity in in vitro and in vivo studies without affecting the antitumor effect. In the present phase I study, the possible side effects and the pharmacokinetics of monoHER were evaluated in healthy volunteers with the aim to develop a safe and feasible dose to be evaluated in cancer patients treated with doxorubicin. The study was performed as a single blind, randomized trial in healthy volunteers (age between 19 and 56 years). At each dose level, six subjects received monoHER and three placebo. MonoHER was solubilized in 100 ml dextrose 5% and administered as an i.v. infusion in 10 min. The placebo consisted of 100 ml dextrose 5%. The starting dose of monoHER was 100 mg/m(2). Dose escalation by 100% of the preceding dose took place after finishing each dose level until the protecting pharmacokinetic values for C (max) and AUC(infinity) (as observed in mice after 500 mg/kg monoHER i.p.) were reached and/or serious side effects were observed. The dose was escalated up to 1,500 mg/m(2). The mean values of C (max) and AUC(infinity) were 360+/-69.3 microM and 6.8+/-2.1 micromol min/ml, respectively. These values were comparable to the C (max) and AUC(infinity) observed under the protecting conditions in mice. No serious side effects occurred during the entire study. Thus, 1,500 mg/m(2) is a feasible and safe dose to be evaluated in a phase II study to investigate the protective properties of monoHER against doxorubicin-induced cardiotoxicity in cancer patients.

In vivo reduction of erythrocyte oxidant stress in a murine model of beta-thalassemia.

BACKGROUND AND OBJECTIVES: Oxidant damage is an important contributor to the premature destruction of erythrocytes and anemia in thalassemias. To assess the extent of oxidant damage of circulating erythrocytes and the effects of antioxidant therapy on erythrocyte characteristics and anemia, we used a mouse model of human beta-thalassemia intermedia (b1/b2 deletion). DESIGN AND METHODS: Several parameters indicative of oxidant damage were measured at baseline and following administration of the semi-synthetic flavonoid antioxidant, 7-monohydroxyethylrutoside (monoHER), to beta-thalassemic mice at a dose of either 500 mg/kg i.p. once a day (n=6) or 250 mg/kg i.p. twice a day (n=6) for 21 days. RESULTS: Significant erythrocyte oxidant damage at baseline was indicated by: (i) dehydration, reduced cell K content, and up-regulated K-Cl co-transport; (ii) marked membrane externalization of phosphatidylserine; (iii) reduced plasma and membrane content of vitamin E; and (iv) increased membrane bound IgG. MonoHER treatment increased erythrocyte K content, and markedly improved all cellular indicators of oxidant stress and of lipid membrane peroxidation. While anemia did not improve, monoHER therapy reduced reticulocyte counts, improved survival of a fraction of red cells, and reduced ineffective erythropoiesis with decreased total bilirubin, lactate dehydrogenase and plasma iron. INTERPRETATION AND CONCLUSIONS: Antioxidant therapy reverses several indicators of oxidant damage in vivo. These promising antioxidant effects of monoHER should be investigated further.

Bioavailability and pharmacokinetics of the cardioprotecting flavonoid 7-monohydroxyethylrutoside in mice.

PURPOSE: The pharmacokinetics and bioavailability of monoHER, a promising protector against doxorubicin-induced cardiotoxicity, were determined after different routes of administration. METHODS: Mice were treated with 500 mg.kg(-1) monoHER intraperitoneally (i.p.), subcutaneously (s.c.) or intravenously (i.v.) or with 1000 mg.kg(-1) orally. Heart tissue and plasma were collected 24 h after administration. In addition liver and kidney tissues were collected after s.c. administration. The levels of monoHER were measured by HPLC with electrochemical detection. RESULTS: After i.v. administration the AUC(0-120 min) values of monoHER in plasma and heart tissue were 20.5+/-5.3 micromol.min.ml(-1) and 4.9+/-1.3 micromol.min.g(-1) wet tissue, respectively. After i.p. administration, a mean peak plasma concentration of about 130 microM monoHER was maintained from 5 to 15 min after administration. The AUC(0-120 min) values of monoHER were 6.1+/-1.1 micromol.min.ml(-1) and 1.6+/-0.4 micromol.min.g(-1) wet tissue in plasma and heart tissue, respectively. After s.c. administration, monoHER levels in plasma reached a maximum (about 230 microM) between 10 and 20 min after administration. The AUC(0-120 min) values of monoHER in plasma, heart, liver and kidney tissues were 8.0+/-0.6 micromol.min.ml(-1), 2.0+/-0.1, 22.4+/-2.0 and 20.5+/-5.7 micromol.min.g(-1), respectively. The i.p. and s.c. bioavailabilities were about 30% and 40%, respectively. After oral administration, monoHER could not be detected in plasma, indicating that monoHER had a very poor oral bioavailability. CONCLUSIONS: MonoHER was amply taken up by the drug elimination organs liver and kidney and less by the target organ heart. Under cardioprotective conditions (500 mg/kg, i.p.), the Cmax was 131 microM and the AUC(infinity) was 6.3 microM.min. These values will be considered endpoints for the clinical phase I study of monoHER.

Pharmacokinetics of mono-3'- and mono-4'-0-(beta-hydroxyethyl)-rutoside derivatives, after single doses of Venoruton powder in healthy volunteers.

BACKGROUND: Venoruton is a standardised mixture of O-(beta-hydroxyethyl) rutosides (HR) used for the relief of oedema and related symptoms in patients with chronic venous insufficiency. OBJECTIVES. The primary objective was to evaluate the pharmacokinetic parameters, in particular the rate and extent of absorption (bioavailability) of two markers of Venoruton: mono-3'-HR and mono-4'-HR derivatives [glucuroconjugated forms (HG)], analysed in their deconjugated form as O-(beta-hydroxyethyl)-quercetin (HQ): mono-3'-HQ and mono-4'-HQ, and to investigate dose proportionality. A secondary objective was to evaluate the general safety of the different dosages. METHODS: In this open, single-dose, randomised, four-way, crossover study, 16 healthy volunteers received four different oral doses of Venoruton powder (0.5, 1, 2 or 4 g). Eighteen blood samples were obtained between 10 min pre-dose and 120 h post-dose. RESULTS: Peak plasma concentration (C(max)) and area under the plasma concentration-time curve (AUC) of mono-3'-HQ were or tended to be proportional to the dose between 1 g and 4 g. The dose proportionality could be extended to the 0.5-g dose, although C(max) and AUC were not always estimable at that dose level (due to the low number of data points above the limit of quantification). For mono-4'-HQ, the increase of C(max) and AUC was also or tended to be proportional to the dose over the whole tested range (0.5-4 g). Time to peak concentration of both Venoruton derivatives remained unaffected by the administered dose. The elimination half-life of both molecules was very similar with the three highest doses. It was shorter with the 0.5-g dose but was not accurately estimated (or even not estimable in some subjects) due to the low number of points above the limit of quantification. CONCLUSIONS: The bioavailability of both Venoruton derivatives (mono-3'-HQ and mono-4'-HQ) tended to be proportional to the dose. The rate of appearance and the elimination half-life of both molecules were not modified with the administered dose. The different doses of the study medication were safe and well tolerated. Mono-3'-HQ and mono-4'-HQ are therefore new bioanalytic and pharmacokinetic markers for Venoruton.

High-performance liquid chromatography with electrochemical detection for the determination of 7-monohydroxyethylrutoside in plasma.

MonoHER (7-monohydroxyethyl rutoside) is a semisynthetic flavonoid, which can be used as a modulator for doxorubicin-induced cardiotoxicity. To study the pharmacokinetics of monoHER in mice and human an HPLC procedure was developed to measure the level of monoHER in plasma. After extraction of monoHER with methanol, the supernatant was equally diluted (v/v) with 25 mM phosphate buffer (pH 3.33). This solution was analysed by HPLC, using a reversed-phase ODS column, with a mobile phase consisting of 49% methanol and 51% of an aqueous solution containing 10 mM sodium dihydrogen phosphate (pH 3.4), 10 mM acetic acid and 36 microM EDTA. The retention time of monoHER was about 5.2 min. The lower limit of quantification of monoHER was set at 0.3 microM and the calibration line was linear up to 75 microM. The within-day accuracy and precision of the quality control samples (0.45, 1.0, 10 and 40 microM) were better than 15 and 13%, respectively. The between-day accuracy and precision were less than 3, 20%, respectively. The recovery of monoHER (using quality control concentrations) was concentration independent and ranged from 90.5 to 95.3% except for the lowest quality control, 0.45 microM, of which the recovery was 85%. The concentration of monoHER in plasma decreased with 10% when stored at -80 degrees C for one month and with 20% when stored at -20 degrees C for 3 weeks. The repeated injection of monoHER in aliquots of 10 microM, stored in the autosampler tray (4 degrees C), showed a consistent decrease during a run: 15% over 24 h. To compensate for this decrease, sample duplicates were analysed in a mirror image sequence.

Pharmacodynamics of troxerutine in patients with chronic venous insufficiency: correlations with plasma drug levels.

In a double-blind study the effects of troxerutine were assessed in patients with chronic venous insufficiency. The aim of this clinical pharmacological research was to evaluate, after a single oral dose: haemocoagulative and fibrinolytic balance, haemorheological changes and venous function. Correlation between such changes and simultanously assayed plasma drug levels was evaluated. The data obtained seems to give to troxerutine a more enlarged pharmacological characterization, especially regarding its demonstrated profibrinolytic and rheological activities. The maximal pharmacodynamic effects appeared simultaneous with the plasma drug peak.

[HPLC determination of troxerutin in plasma and urine following oral administration in man]. / HPLC-Bestimmung von Troxerutin im Plasma und Harn nach oraler Gabe am Menschen.

A high-performance liquid chromatographic method (HPLC) is described for the analysis of 3',4',7-tri-O-(beta-hydroxy-ethyl)-rutoside (troxerutin) in human plasma and urine. After separation of interfering substances on XAD-2 trihydroxyethylrutoside is converted to tetrahydroxyethylrutoside by 2-chlorethanol in alkaline medium. After HPLC-separation tetrahydroxyethylrutoside is quantified by fluorescence detection. The pharmacokinetics of troxerutin were measured in plasma after oral administration to man. The relative bioavailability of the drug from Venelbin was 97.8 +/- 37.1% compared to an aqueous standard solution.

Quantitative determination of O-(beta-hydroxyethyl)-rutosides in serum by high-performance liquid chromatography.

A procedure for the quantitative determination of O-hydroxyethylated rutosides by high-performance liquid chromatography is described, which can be used for the detection of these modified flavonoids in human serum. Serum samples are processed by the addition of acetone, which removes most of the proteins. After passing the supernatant through a microcolumn of Amberlite XAD-2 and washing with water, the hydroxyethylated rutosides are eluted with methanol. The eluate is concentrated in vacuo. The methanolic solution of the residue is chromatographed on RP-8 columns using UV and fluorescence detectors. The mono- to tetrahydroxyethylated constituents and their corresponding aglycones could be separated with a step gradient, starting with a solvent system of water-methanol-acetic acid (70:30:6) followed by a mixture of water-ethanol-acetic acid (70:30:6). Alternatively, the rutosides can be separated by a linear gradient of water-acetonitrile. An almost linear calibration curve and about 80% recovery are obtained. A detection limit of 1 mg/l is achieved. Pharmacokinetic studies in human volunteers are described.

[Studies in animal experiments on determination of blood and organ levels of o-(beta-hydroxyethyl)-rutosides (HR) after i.p. administration (author's transl)]. / Tierexperimentelle Untersuchungen zur Bestimmung von Wirkstoffkonzentrationen in Blut und Organen nach intraperitonealer Verabreichung von O-(beta-Hydroxyethyl)-rutosiden.

The concentration of O-(beta-hydroxyethyl)-rutosides (HR, Venoruton) in different organs and serum was investigated after i.p. injections in C3H-mice. There was found a distinct but brief maximum level in serum within 10 to 25 min after i.p. injection. This result explains some of the positive and negative papers about the problem of radiation protection by HR. Therefore it seems important to expand knowledge on time factors and excretion mode of HR in different organs and serum to judge on the radioprotective ability of this substance.

The metabolism and excretion of 7-mono-0-(beta-hydroxyethyl) rutoside in the dog.

Following i.v. administration of mono-HR to the beagle, plasma levels of both mono-HR and its glucuronide conjugates fell rapidly, neither being detectable 8 h after injection. Following oral administration of 14C-mono-HR, mono-HR-glucuronide was detected in plasma, confirming the absorption of mono-HR, and low levels of 14C were detectable up to 72 h after dosage. Following either oral or i.v. administration of mono-HR, the major route of excretion was fecal elimination of the compound as its aglycone form. Urinary excretion was slight being less than 15% following i.v. dosage and 4% following oral administration. Metabolism of mono-HR was confined to glucuronidation and hydrolytic cleavage of the glycoside side chain. Ring fission products of mono-HR were not detected.

Determination of individual hydroxyethyl rutosides in various animal body fluids by thin-layer chromatography and scanning densitometry.

A method is described for the accurate determination in plasma of the beta-hydroxyethylrutosides by measurement of the fluorescence of their borocitrate complexes by scanning densitometry following separation by thin-layer chromatography. A modification is also described for estimation of individual hydroxyethylrutosides and their glucuronide conjugates in samples of bile and urine.

The effect of O-(beta-hydroxyethyl)-rutoside (HR) on macromolecular leakage, thrombosis and haemostasis in experimental animals.

O-(beta-hydroxyethyl)-rutoside (HR) (Venoruton, Zyma AS, Nyon, Switzerland) has been investigated experimentally to evaluate the effect on microvascular permeability and thromboembolism. Permeability to macromolecules is diminished in a hamster cheek-pouch model. Haemostatic plug formation is impaired whereas laser-induced intravascular platelet aggregation is uninfluenced. There is a small but insignificant protection against sodium morrhuate (Eli Lilly and Co., Indianapolis, Indiana) induced femoral vein thrombosis.