Introduction
. Viral infections are a serious problem that occurs during the use of immunosuppressants in preparation for organ transplantation and in the postoperative period. Cytomegalovirus (CMV) ...infection is one of the main causes of diseases in people with weakened immune systems. It has a direct impact on one’s body and makes it more likely to reject a transplanted organ. Antiviral drugs are used to treat and prevent this infectious disease. Valganciclovir is a prodrug whose active metabolite is ganciclovir. Valganciclovir is the drug of choice in the treatment of CMV infections. Currently, there are no researches on the matter of simultaneous determination of both valganciclovir and ganciclovir in human blood plasma by means of high-performance liquid chromatography (HPLC) with ultraviolet detection. This research delivers a thorough description of development and validation of a particular method for simultaneous determination of valganciclovir and ganciclovir in the plasma after sample preparation by the method of protein precipitation.
Aim
. The aim of this study is to develop method for the quantitative determination of valganciclovir and its active metabolite ganciclovir in human plasma by HPLC-UV for pharmacokinetic studies.
Materials and methods
. Quantitative determination of tadalafil in plasma by HPLC-UV. A sample was prepared using protein precipitation.
Results and discussion
. This method was validated by next validation parameters: selectivity, matrix effect, calibration curve, accuracy, precision, lower limit of quantification, carry-over and stability.
Conclusion
. The method of the quantitative determination of valganciclovir and its active metabolite ganciclovir in human plasma was developed and validated by HPLC-UV. The analytical range of the was 5,0–1000,0 ng/ml for valganciclovir and 100,0–10000,0 ng/ml for ganciclovir in plasma. Method could be applied to determination of valganciclovir and ganciclovir in plasma for PK and BE studies.
•Experiments with evaporating suspended water/ethanol droplets in air flow.•Model considering diffusion of species and recirculation inside droplets.•The effect of supporting thread is considered ...using an earlier developed model.•Considering the effect of thread is shown to improve the model prediction.•Model predictions are compatible with experimental data.
The paper focuses on experimental investigation and modelling of the evaporation of supported ethanol/water droplets in an air flow. The modelling is based on the effective thermal conductivity/effective diffusivity model, using the analytical solutions to the transient heat transfer and species diffusion equations in droplets at each time step. The contribution of the supporting thread is included in the model. Model predictions are shown to be compatible with experimental data. For all mass fractions of ethanol, droplet surface temperatures rapidly decrease initially. This is followed by an increase in this temperature for non-zero mass fractions of ethanol in the mixture. For pure water this temperature remains almost constant after an initial decrease. In all cases, droplet diameters to power 1.5 decrease almost linearly with time. This agrees with model predictions in the limit for large droplet Reynolds numbers.
A new database of fire activity in Russia derived from 1-km resolution remote sensing imagery is presented and discussed. The procedure used to generate this burned-area product is described, ...including active-fire detection and burn-scar mapping approaches. Fire detection makes use of a probabilistic procedure using image data from the United States National Oceanic and Atmospheric Administration's (NOAA) advanced very high resolution radiometer (AVHRR) system. Using the combination of AVHRR data collected at the Krasnoyarsk, Russia, high-resolution picture transmission (HRPT) receiving station, and data from the NOAA Satellite Active Archive (SAA), fire maps are being created for all of Russia for 1995 to 1997 and all of Eastern Russia (east of the Ural Mountains) for 1995 to 2002. This mapping effort has resulted in the most complete set of historic fire maps available for Russia. An initial validation indicates that the burned-area estimates are conservative because the approaches do not detect smaller fires, and, in many cases, fire areas are slightly underestimated. Analyses using the fire database showed that an average of 7.7×10
6 ha yr
−1 of fire occurred in Eastern Russia between 1996 and 2002 and that fire was widely dispersed in different regions. The satellite-based burned-area estimates area were two to five times greater than those contained in official government burned-area statistics. The data show that there is significant interannual variability in area burned, ranging between a low of 1.5×10
6 ha in 1997 to a high of 12.1×10
6 ha in 2002. Seasonal patterns of fire are similar to patterns seen in the North American boreal region, with large-fire seasons experiencing more late-season burning (in August and September) than during low-fire years. There was a distinct zonal distribution of fires in Russia; 65% of the area burned occurred in the taiga zone, which includes southern, middle, and northern taiga subzones, 20% in the steppe and forest steppe zones, 12% in the mixed forest zone, and 3% in the tundra and forest-tundra zones. Lands classified as forest experienced 55% of all burned area, while crops and pastures, swamps and bogs, and grass and shrubs land cover categories experienced 13% to 15% each. Finally, the utility of the products is discussed in the context of fire management and carbon cycling.
Introduction.
Tadalafil is a drug used to treat erectile dysfunction. For the quantitative determination of tadalafil in human plasma are used methods of high performance liquid chromatography with ...ultraviolet and tandem mass spectrometric detection, during the analytical part of pharmacokinetic studies. In the majority of the considered methods the method of liquid-liquid extraction and the method of solid-phase extraction are used, these methods are difficult and expensive. Therefore, the method of protein precipitation was considered as sample preparation. This method is simple and there is important to analysis a lot of clinical samples in bioequivalence studies.
Aim.
The aim of this study is to develop method for the quantitative determination of tadalafil in human plasma by HPLC-MS for the analytical part of pharmacokinetic studies.
Materials and methods.
Quantitative determination of tadalafil in plasma by HPLC-MS. A sample was prepared using acetonitrile protein precipitation.
Results and discussion.
This method was validated by next validation parameters: selectivity, matrix effect, calibration curve, accuracy, precision, lower limit of quantification, carry-over and stability.
Conclusion.
The method of the quantitative determination of tadalafil in human plasma was developed and validated by HPLC-MS. The analytical range of the was 5,00–1000,00 ng/ml tadalafil in plasma. Method could be applied to determination of tadalafil in plasma for PK and BE studies.
Introduction. HIV infection is one of the most relevant diseases from a medical, epidemiological and social point of view. Timely diagnosis, detection and control of the disease, adequate ...prescription of antiretroviral therapy can sufficiently reduce the viral load on the patient's body, reduce the risk of transmission of infection. Currently, combinations of various antiretroviral drugs are increasingly being prescribed as therapy. One of the most important is combination of atazanavir and ritonavir. The most important stage for the study of pharmacokinetics, studies of comparative pharmacokinetics and bioequivalence is the development of an analytical method that allows you to determine the investigated substances in human plasma. There are currently no published methods for the determination of atazanavir and ritonavir in human plasma using high performance liquid chromatography with mass selective detection using a single quadrupole mass detector. In this article presents the development and validation of a method for the determination of atazanavir and ritonavir in blood plasma after sample preparation by the method of protein precipitation.Aim. The aim of the study is to develop a method for the quantitative determination of atazanavir and ritonavir in human plasma by HPLC with mass spectrometric detection for performing the analytical part of pharmacokinetic studies.Materials and methods. Determination of atazanavir and ritonavir in human plasma by HPLC with mass spectrometric detection. A sample was prepared using protein deposition.Results and discussion. The method was validated of selectivity, matrix effect, calibration curve, accuracy, precision, limit of quantification, carry-over effect and sample stability.Conclusion. The method of the determination of atazanavir and ritonavir in human plasma was developed and validated by HPLC-MS. The analytical range of the was 50.0–10000.0 ng/mL in plasma for atazanavir and 10.0–2500.0 ng/mL in plasma for ritonavir. Method could be applied to determination of atazanavir and ritonavir in plasma for PK and BE studies.
Introduction.
Human Immunodeficiency Virus (HIV) is one of the main socially significant infection all over the world. HIV-positive patients take medical care, including antiretroviral drugs (ARVs) ...pharmacotherapy. Like all drugs, ARVs have lots of side effects that should be taken when prescribing drugs as part of highly active antiretroviral therapy. There are many cases when side effects of ARVs caused patients to enter the toxicology department. Therefore, the development of new methods for the analysis of ARV in biological fluids for the timely diagnosis of treatment of poisoning of this group of drugs is relevant today.
Aim
. The aim of this study is development of screening analysis of atazanavir, abacavir, nevirapine, ritonavir, lopinavir, zidovudine, darunavir and efavirenz in the urine to identify these drugs as possible toxicants for poisoning by high-performance liquid chromatography with tandem massselective detection (HPLC-MS/MS).
Materials and methods
. Identification of ARV was performed by HPLC-MS/MS. Methanol precipitation method was used as a sample preparation.
Results and discussion
. The optimal conditions for sample preparation, chromatographic separation, and mass-spectrometric detection were selected to determine the studied ARVs. This method was tested on urine samples from patients in the Department of Acute Poisoning and Somatopsychiatric Disorders (OOSPD) with acute ARV poisoning.
Conclusion.
This screening method for analyse atazanavir, abacavir, nevirapine, ritonavir, lopinavir, zidovudine, darunavir and efavirenz in human urine has been developed by HPLC-MS/MS. The developed method can be used to identify these drugs as possible toxicants in case of poisoning. The prospect for the development of the topic is the inclusion of new molecules in the method and quantitative determination of the studied ARVs.
Introduction
. Multicomponent oral drugs containing salbutamol, bromhexine, ambroxol and guaifenesin have a mucolytic, expectorant and bronchodilator effect. The development method for determination ...substances in biological fluids is a main procedure for performing the analytical part of pharmacokinetic studies and bioequivalence studies of multicomponent drugs. There is no published data of the determination of bromhexine, ambroxol and guaifenesin, but there a lot of published methods for divided determination analytes in a biological fluid. This study presents the development and validation of a method of the determination of salbutamol, bromhexine, ambroxol and guaifenesin in human blood plasma by high performance liquid chromatography with tandem mass spectrometric detection. A sample preparation was perfomed by solid-phase extraction. Deuterated derivatives were used as internal standards.
Aim
. The aim of the study is to develop a method for the quantitative determination of salbutamol, bromhexine, ambroxol and guaifenesin in human plasma by HPLC with tandem mass spectrometric detection for performing the analytical part of pharmacokinetic studies.
Materials and methods
. Determination of salbutamol, bromhexine, ambroxol and guaifenesin in human plasma by HPLC with tandem mass spectrometric detection. A sample was prepared using solid-phase extraction.
Results and discussion
. The method was validated by next validation parameters: selectivity, matrix effect, calibration curve, accuracy, precision, limit of quantification, carry-over and stability.
Conclusion
. The method of the determination of salbutamol, bromhexine, ambroxol and guaifenesin in human plasma was developed and validated by HPLC-MS/MS. The analytical range of the was 0.1–20 ng/mL in plasma for salbutamol, 0.25–25 ng/mL in plasma for bromhexine, 0.075–3 ng/mL in plasma for ambroxol, and 10–2000 ng/mL in plasma for guaifenesin. Method could be applied to determination of salbutamol, bromhexine, ambroxol and guaifenesin in plasma for PK and BE studies.
The results of experimental studies and modelling of the evaporation of suspended water droplets containing silicon dioxide SiO
2
nanoparticles at mass fractions 0.02 and 0.07 are presented. The ...experimental results are analysed using the previously developed model for multicomponent droplet heating and evaporation. In this model droplets are assumed to be spherical and the analytical solutions to the heat transfer and species diffusion equations are incorporated into the numerical code. They are used at each timestep of the calculations. Silicon dioxide nanoparticles are considered to be a non-evaporating component. It is demonstrated that both experimental and predicted values of droplet diameters to the power 1.5 decrease almost linearly with time, except at the beginning and the final stages of the evaporation process, and are only weakly affected by the presence of nanoparticles. At the final point in this process, the effect of nanoparticles becomes dominant when their mass fraction at the droplet surface reaches about 40 % and a cenosphere-like structure is formed. Both predicted and observed droplet surface temperatures rapidly decrease during the initial stage of droplet evaporation. After about
t
=
100
s the predicted surface temperature remains almost constant whilst its experimentally observed values increase with time. This might be related to a decrease in the temperature of ambient air in the vicinity of droplets, not taken into account in the model. Both observed and predicted values of the mass fraction of silicon dioxide at the droplet surfaces are shown to increase with time until they reach about 0.4.
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