Robust HPLC-MS/MS method for levofloxacin and ciprofloxacin determination in human prostate tissue.

Fluoroquinolones are the drugs of choice in the prevention of bacterial infections after transrectal ultrasound guided prostate biopsy. In order to improve assessment of antibacterial efficacy in the target tissue a simple, selective, rapid and robust HPLC-ESI-MS/MS method for the determination of levofloxacin and ciprofloxacin concentrations in human prostate bioptates was developed and validated. Preparation procedure for prostate samples (10mg) was carried out using homogenization and filtration steps. Analyses were performed within 3.5min using RP C18 column in the isocratic elution mode with mobile phase composed of a mixture of 0.1% formic acid aqueous solution and 0.1% formic acid methanol solution (v/v; 79:21). The method was linear between 0.3µg/g and 15µg/g for levofloxacin and ciprofloxacin with coefficient of correlation (r) ≥0.999. The limit of detection and the limit of quantification for levofloxacin were 0.06µg/g and 0.2µg/g and for ciprofloxacin were 0.04µg/g and 0.13µg/g, respectively. Average concentrations (±SD) of levofloxacin and ciprofloxacin obtained from patients tissue were 5.4±2.2µg/g and 3.9±1.5µg/g, respectively. Additionally, during validation procedure a novel, experimental design approach was applied for the robustness study. For evaluation of analytical method robustness, Plackett-Burman design was employed and for sample preparation method robustness Fractional Factorial design was used. The developed and validated method was successfully applied to examine prostate tissue samples obtained from patients enrolled into a clinical study. Up to now, there has been no other HPLC-ESI-MS/MS method reported for the simultaneous determination of levofloxacin and ciprofloxacin in human prostatic tissue.

Ultra-high performance liquid chromatographic determination of levofloxacin in human plasma and prostate tissue with use of experimental design optimization procedures.

Fluoroquinolones are considered as gold standard for the prevention of bacterial infections after transrectal ultrasound guided prostate biopsy. However, recent studies reported that fluoroquinolone- resistant bacterial strains are responsible for gradually increasing number of infections after transrectal prostate biopsy. In daily clinical practice, antibacterial efficacy is evaluated only in vitro, by measuring the reaction of bacteria with an antimicrobial agent in culture media (i.e. calculation of minimal inhibitory concentration). Such approach, however, has no relation to the treated tissue characteristics and might be highly misleading. Thus, the objective of this study was to develop, with the use of Design of Experiments approach, a reliable, specific and sensitive ultra-high performance liquid chromatography- diode array detection method for the quantitative analysis of levofloxacin in plasma and prostate tissue samples obtained from patients undergoing prostate biopsy. Moreover, correlation study between concentrations observed in plasma samples vs prostatic tissue samples was performed, resulting in better understanding, evaluation and optimization of the fluoroquinolone-based antimicrobial prophylaxis during transrectal ultrasound guided prostate biopsy. Box-Behnken design was employed to optimize chromatographic conditions of the isocratic elution program in order to obtain desirable retention time, peak symmetry and resolution of levofloxacine and ciprofloxacine (internal standard) peaks. Fractional Factorial design 2(4-1) with four center points was used for screening of significant factors affecting levofloxacin extraction from the prostatic tissue. Due to the limited number of tissue samples the prostatic sample preparation procedure was further optimized using Central Composite design. Design of Experiments approach was also utilized for evaluation of parameter robustness. The method was found linear over the range of 0.030-10µg/mL for human plasma and 0.300-30µg/g for human prostate tissue samples. The intra-day and inter-day variability for levofloxacine from both plasma and prostate samples were less than 10%, with accuracies between 93 and 108% of the nominal values. The limit of detection and the limit of quantification for human plasma were 0.01µg/mL and 0.03µg/mL, respectively. For the prostate tissue, the limit of detection and the limit of quantification were 0.1µg/g and 0.3µg/g, respectively. The average recoveries of levofloxacin were in the range from 99 to 106%. Also, the method fulfills requirements of robustness what was determined and proved by Design of Experiments. The developed method was successfully applied to examine prostate tissue and plasma samples from 140 hospitalized patients enrolled into the clinical study, 12h after oral administration of LVF at a dose of 500mg. The mean (±SD) LVF concentration in prostate was 6.22±3.52µg/g and in plasma 2.54±1.14µg/mL. Due to simplicity of the method and relative small amount of sample needed for the assay, the method can be applied in clinical practice for monitoring of LVF concentrations in plasma and prostate gland.

GC-MS and LC-MS approaches for determination of tocopherols and tocotrienols in biological and food matrices.

Tocopherols and tocotrienols, widely described as vitamin E derivatives, have been proven to take part in a number of important biological functions. Among them, antioxidant properties had been investigated and documented in the literature. Since tocochromanols have revealed their plausible beneficial impact on several pathological processes, such as cancerogenesis or cognitive impairment diseases, there is a growing interest in quantitative determination of these compounds in biological fluids, tissues and plant organs. However, due to vitamin E chemical features, such as lipophilic and non-polar characteristics, quantitative determination of the compounds seems to be problematic. In this paper we present current analytical approaches in tocopherols and tocotrienols determination in biological and food matrices with the use of chromatographic techniques, especially gas chromatography (GC) and high performance liquid chromatography (HPLC) coupled with mass spectrometry. Derivatization techniques applied for GC-MS analysis in the case of tocol derivatives, especially silylation and acylation, are described. Significant attention is paid to ionization process of tocopherols and tocotrienols.

Studies of the effect of grasshopper abdominal secretion on wound healing with the use of murine model.

ETHNOPHARMACOLOGICAL RELEVANCE: Grasshopper, belonging to Chorthippus sp., is a widespread insect inhabiting Polish territory. According to folk knowledge and folk tales, the grasshopper abdominal secretion was used by villagers of Central and South-West Poland as a natural drug accelerating the wound healing process. AIM OF THE STUDY: In the reported study the hypothesis about beneficial properties of grasshopper abdominal secretion on hard to heal wounds was verified. MATERIALS AND METHODS: The study was carried out with the use of a murine model (mice C57BL/6). In order to verify the beneficial properties of grasshopper abdominal secretion, the wounds of 8mm in diameter were formed on one side of each tested mouse. The influence of ethanolic extract of insects' secretion on healing process was evaluated in comparison to ethanolic solution of allantoin and 30% aqueous solution of ethanol (medium). The observation was carried out over a 14 day period. Finally the statistical analysis (ANOVA) was carried out to highlight the differences in wound healing rate between applied preparations. Moreover, qualitative composition of grasshoppers' secretion was studied with the use of GC/MS technique. RESULTS: During the first three days of observation, wounds treated with allantoin were healed with higher efficiency in comparison to ethanol and insect secretion preparations. The trend of healing changed from the 4th day of observation. Wounds treated with grasshoppers' abdominal secretion were closuring faster than wounds treated with allantoin or ethanol. In this part of observation, in the case of allantoin and ethanol application, the wound healing efficiency was similar. Since the 9th day of experiment the measurement of wounds size was problematic, due to crust formation. Finally at the 14th day of the study, wounds were totally healed. Morphological study enabled to observe all the phases of healing. In the 5th and 8th day, the infiltration of neutrophils and mononuclear cells in dermis was observed, which is characteristic for inflammatory phase of wound healing. On the 8th day of experiments, granulation of the tissue was clearly observed in the tested groups. Reepithelialization phase was observed from the 5th to 14th day, when the wound was totally healed. The analytical approach enabled to identify 38 compounds of hydrophobic or hydrophilic character. Among them, 6 amino acids, 14 organic acids and their derivatives, one sterol, 4 hydrocarbons, 5 carbohydrates, 2 inorganic acids, 4 alcohols, one diamine and one nucleoside were identified. CONCLUSION: The obtained results enabled to recognize the composition of grasshopper abdominal secretion. Some of the identified compounds possess therapeutic properties described in the literature. The performed in vivo study proved that application of insects secretion accelerates the healing process. The obtained results positively verified the scientific hypothesis based on ethnopharmacological premises about the beneficial properties of grasshopper abdominal secretion on wound healing process.

The simultaneous determination of hydrophobicity and dissociation constant by liquid chromatography-mass spectrometry.

Convenient methods for testing drug candidates' lipophilicity and acidity are highly requested in modern pharmaceutical research and drug development strategies. Reversed-phase high-performance liquid chromatography (RP HPLC) might be particularly useful for the determination of both dissociation constant and the (pH-dependent) partition coefficient related parameters, applicable in high-throughput analysis of multi-component mixtures. The general theory of combined pH/organic modifier gradient has recently provided equations relating gradient retention time and pH of the mobile phase. The purpose of this work was to facilitate the identification of analytes in this technique by its transfer to RP HPLC coupled with time-of-flight mass spectrometry with electrospray ionization source (ESI-TOF-MS). The accuracy of the proposed methodology was assessed by analyzing a set of known drugs. The ammonium formate, ammonium acetate or ammonium bicarbonate buffers were used to control pH during chromatographic analysis. In result, the pKa and hydrophobicity parameters were determined and the accuracy of the estimated values was assessed by comparing them with literature data. The gradient RP HPLC coupled with ESI-TOF-MS methods allowed for the rapid determination of dissociation constant and hydrophobicity and was shown to be especially applicable for complex mixtures. The use of ESI-TOF-MS detection allowed to achieve the medium-throughput screening rate (100 compounds/day) and provided a simple approach to assess pharmacokinetically important physicochemical properties of drugs.

Pharmacokinetics and metabolism of (R,R)-methoxyfenoterol in rat.

(R,R)-fenoterol (Fen), a beta(2)-adrenoceptor agonist, is under clinical investigation in the treatment of congestive heart disease. The pharmacokinetics and metabolism of the 4-methoxyphenyl derivative of (R,R)-Fen, (R,R)-MFen, have been determined following intravenous and oral administration to the rat and compared with corresponding results obtained with (R,R)-Fen. Results from the study suggest that (R,R)-MFen can offer pharmacokinetic and metabolic advantages in comparison to an earlier (R,R)-Fen. The oral administration revealed that the net exposure of (R,R)-MFen was about three-fold higher than that of (R,R)-Fen (7.2 versus 2.3 min x nmol ml(-1)), while intravenous administration proved that the clearance was significantly reduced, 48 versus 146 ml min(-1) kg(-1), the T(1/2) was significantly longer, 152.9 versus 108.9 min, and the area under the curve (AUC) was significantly increased, 300 versus 119 min x nmol ml(-1). (R,R)-MFen was primarily cleared by glucuronidation associated with significant presystemic glucuronidation of the compound. After intravenous and oral administration of (R,R)-MFen, (R,R)-Fen and (R,R)-Fen-G were detected in the urine samples indicating that (R,R)-MFen was O-demethylated and subsequently conjugated to (R,R)-Fen-G. The total (R,R)-Fen and (R,R)-Fen-G as a percentage of the dose after intravenous administration was 3.6%, while after oral administration was 0.3%, indicating that only a small fraction of the drug escaped presystemic glucuronidation and was available for O-demethylation. The glucuronidation pattern was confirmed by the results from in vitro studies where incubation of (R,R)-MFen with rat hepatocytes produced (R,R)-MFen-G, (R,R)-Fen and (R,R)-Fen-G, while incubation with rat intestinal microsomes only resulted in the formation of (R,R)-MFen-G.

Antiaggregatory activity of hypoglycaemic sulphonylureas.

AIMS/HYPOTHESIS: Vascular complications observed in diabetes are often related to altered platelet functions. The most widely used hypoglycaemic drugs for treating Type II (non-insulin-dependent) diabetes mellitus are sulphonylurea derivatives. The purposes of this study were to evaluate the inhibitory effects of hypoglycaemic agents on platelet aggregation, to measure their lipophilicity and identify their structural parameters which assess their antiaggregatory activity. METHODS: An antiaggregatory test in vitro was carried out for 13 sulphonylurea derivatives. Aggregation of platelets, incubated with the agents at concentrations varying from 7.5 to 480 micromol/l, was induced by 10 micromol/l ADP. Drug lipophilicity parameter, log k(w), was measured by gradient HPLC and the agents were subjected to molecular modelling. RESULTS: The most pronounced inhibition of platelet aggregation was by glimepiride, gliclazide, gliquidone, glibenclamide and compound 2A. The IC(25) values were 15.9, 18.6, 20.4, 28.5 and 34.7 micromol/l, respectively. Quantitative structure-activity relationships indicate that antiaggregatory activity is mainly affected by electronic and not by lipophilic properties of the agents. CONCLUSION/INTERPRETATION: Glimepiride appeared to be a more potent ADP-induced platelet aggregation inhibitor in vitro than gliclazide. Antiaggregatory activity was shown for gliquidone and confirmed for glibenclamide. The QSAR analysis supports the hypothesis of a free radical mechanism of action of sulphonylurea derivatives previously suggested for gliclazide.

Synthesis and hypolipidemic and antiplatelet activities of alpha-asarone isomers in humans (in vitro), mice (in vivo), and rats (in vivo).

A series of alpha-asarone isomers was synthesized and investigated for their hypolipidemic and antiplatelet activity. Considering the hypolipidemic activity in rats at a dose of 80 mg/kg/day, some isomers were more potent than clofibrate at 150 mg/kg. Compound 3 was one of the most active agents elevating the HDL cholesterol level by 56% and lowering the LDL cholesterol level by 46.8% in rats after 7 days of administration. The activities of the platelet aggregation test in vitro were significant but lower than those of the reference substances (indomethacine and acetylsalicylic acid). In the pulmonary thromboembolic in vivo test in mice, two compounds (alpha-asarone (6) and compound 4) produced significant antithrombotic effects at 100 mg/kg, namely 44% and 52% protection against lung microembolia, respectively. alpha-Asarone derivatives form a new group of potential hypolipidemic and/or antithrombotic agents. The compounds 3, 4, and 6 may serve as lead substances whose structural modifications may result in original drugs.

Comparative study of antithrombotic and antiaggregatory activity of acetylsalicylic acid, ticlopidine and a new noncarboxylic acid antiinflammatory pyrazine derivative HF90.

The action of acetylsalicylic acid, ticlopidine and a new pyrazine derivative HF90 selected in preliminary screenings (11, 18, 19) was studied by using the mouse antithrombotic assay according to DiMinno and Silver (22) and in vitro blood platelet aggregation method according to Born (23). Acute pulmonary thromboembolism was induced by injection of a mixture of collagen and epinephrine into the mouse tail vein. The effect of HF90, an acidic pyrazine derivative possessing active methylene moiety, administered at doses of 50 and 100 mg/kg, was compared to the action of the well established antithrombotic agents: ticlopidine (100 mg/kg) and acetylsalicylic acid (20 mg/kg). The compounds were administered i.p. in single doses 1 h and 24 h before the thrombotic challenge or once a day per three consecutive days before the thrombotic challenge. Ticlopidine appeared to provide the better protection against microembolism than acetylsalicylic acid although its effect has not manifested itself immediately after administration. The pyrazine derivative examined has a lower but significant antithrombotic activity. The chemical class of pyrazine derivatives with active methylene moiety (the so called pyrazine CH/NH-acids) (16) provides a new original antiinflammatory pharmacophore and HF90 may serve as the "lead compound" in the search for new agents of pharmacological interest.