Репозиторий Университета

© 2019 Elsevier B.V. A new sample extraction protocol was developed for pharmacokinetic studies of dabigatran with high-performance liquid chromatography separation - electrospray ionization time-of-flight mass spectrometry analysis. After protein precipitation with acetonitrile, free dabigatran and its metabolites are separated into water phase by water-dichloromethane liquid-liquid extraction to purify the sample from proteins and endogenous lipophilic compounds. Chromatographic separation was achieved on an Agilent Zorbax SB-CN column (150 × 4.6 mm, 5 µm)) using 0.1% aqueous solution of formic acid and acetonitrile (80:20) as the mobile phase. Agilent Zorbax SB-CN column was selected to improve sample resolution and to avoided early elution of dabigatran previously seen when using a C18 column. The extended calibration curve was constructed from 5 to 1000 ng/L while precision and accuracy were assessed at four levels across the linear dynamic ranges. Within-run precision was <5.6% and the between-run precision was <3.9%. The method accuracy ranged from 89.8% to 104.4%. The developed method was successfully applied to 30 patient samples to evaluate antithrombotic efficacy and anticoagulant activity of dabigatran following knee endoprosthesis surgery.

© 2018, Springer Science+Business Media, LLC, part of Springer Nature. A validated method for quantitative determination of flupirtine in human blood plasma using liquid chromatography combined with tandem mass spectrometry (HPLC-MS/MS) was proposed. Biological samples were prepared by precipitating proteins using MeOH. The chromatographic separation used a Zorbax Eclipse Plus C18 column with gradient elution. A Shimadzu 8040 triple quadrupole mass spectrometer in multiple-reaction-monitoring mode (+MRM) with chemical ionization at atmospheric pressure (APCI) was used to determine the molecular ion of flupirtine with m/z 305.2. Acalibration curve for flupirtine was linear (R = 0.994) in the concentration range 25 – 2,500 ng/mL with a lower detection limit of 25 ng/mL. Validation of the method indicated that it was highly sensitive, specific, accurate, and precise and that the analyte was stable. The method was successfully applied to comparative pharmacokinetic studies of drugs containing flupirtine.

© 2018, Springer Science+Business Media, LLC, part of Springer Nature. An HPLC-MS/MS method for determining dabigatran in human blood serum was developed. Samples were prepared by precipitation of proteins using MeOH followed by centrifugation and dilution with deionized H2O. The developed method had a simple sample-preparation procedure, short analysis time, and wide analytical range (from 1 to 1,000 ng/mL). This method was suitable for routine bioanalytical studies, in particular, therapeutic drug monitoring.

© 2018, Springer Science+Business Media, LLC, part of Springer Nature. A method for simultaneous determination of metoprolol and bisoprolol in human blood serum by HPLC-MS/MS was developed and validated. The analytical ranges of the method were 5 – 250 ng/mL and 1 – 250 ng/mL for metoprolol and bisoprolol, respectively. The suitability of the developed for therapeutic drug monitoring during treatment for arterial hypertension and other cardiovascular diseases was demonstrated. In particular, the proposed method could identify patients at high risk for developing adverse effects and help to monitor a switch between metoprolol and bisoprolol while changing the pharmacotherapy regime.

© 2018 Sklifosovsky Research Institute for Emergency Medicine. All rights reserved. BACKGROUND The relative availability of Phenazepam makes it a frequent cause of overdose, suicide and non-medical use. At the same time, it remains insufficiently studied in chemical and toxicological terms. THE AIM OF STUDY to create an accessible, rapid method for detecting Phenazepam in biological matrices of patients with acute poisoning. MATERIALS AND METHODS We used thin-layer chromatography (TLC), gas chromatography with a mass selective detector (GC-MS), high performance liquid chromatography with a tandem mass-selective detector (LC-MS/MS) and immunochromatographic analysis (ICA). The preparation of samples of intact urine with the addition of standard solutions of Phenazepam and real urine samples of patients with acute poisoning with Phenazepam was carried out using liquid-liquid extraction or precipitation of related components of the sample with acetonitrile. Hydrolysis and derivatization were also added in GC-MS analysis. RESULTS The analysis of statistics of the Department of Acute Poisonings of the N.V. Sklifosovsky Research Institute for Emergency Medicine in 2014–2016 showed that Phenazepam poisonings averaged 9.2% of the total number of admissions and mainly occurred as suicidal attempts. A technique has been developed for the detection of Phenazepam by TLC, which gives more objective results than ICA. For confirmatory analysis, it is advisable to use LC-MS/MS method for the native substance and GC-MS for the products of hydrolysis after derivatization. Compared to confirmatory methods, the developed TLC-screening technique is expressive, does not require the use of expensive high-tech equipment, difficult sample preparation, and makes it possible to reliably detect toxic and lethal concentrations of Phenazepam.

© 2018 Bentham Science Publishers. Background: Nitroproston is a novel prostaglandin-based compound modified by NO-donating groups with potential application in obstructive respiratory diseases such as asthma and obstructive bronchitis. Nitroproston has been extensively studied using various pharmacological models. Its biological stability is still uncertain. Objective: The aim of the present study was to evaluate Nitroproston stability in vitro, as well as to identify and characterize its major biodegradation products. Methods: The principal biodegradation products of Nitroproston were identified in vitro using liquid chromatography/ion trap – time-of-flight mass-spectrometry. The postulated structure of metabolites was confirmed using authentic reference standards. Rat, rabbit and human plasma and human whole blood samples were used for comparative in vitro degradation study. Nitroproston and its biodegradation products in biological samples were measured by liquid chromatography/triple –stage quadrupole mass spectrometry. Results: Nitroproston is rapidly hydrolyzed in rat plasma to generate glycerol-1,3-dinitrate and prostaglandin E2 . The latter can undergo conversion to cyclopentenone prostaglandins A2 and B2 . Thereby less than 5% of the parent compound was observed in rat plasma at the first moment of incubation. A similar pattern was observed for rabbit plasma where half-life (T1/2) of Nitroproston was about 2.0 minutes. Nitroproston biodegradation rate for human plasma was the slowest (T1/2 = 2.1 h) among tested species, occurred more rapidly in whole blood (T1/2 = 14.8 min). Conclusion: It was found that Nitroproston is rapidly hydrolyzed in rodent compared to human plasma incubations. Whereas Nitroproston is relatively stable in human plasma an enhanced hydrolytic activity was observed in whole human blood incubations. Extensive metabolism of Nitroproston in human whole blood was mainly associated with red blood cells. The observed interspecies variability highlights the need of suitable animal model selection for Nitroproston follow-up PK/PD studies.