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1

Recent theoretical and practical applications of micellar liquid chromatography (MLC) in pharmaceutical and biomedical analysis

100%

Kawczak P., Bączek T.

Open Chemistry

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2012

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vol. 10

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issue 3

570-584

EN

Micellar liquid chromatography (MLC) is an analytical technique belonging to the wide range of reversed-phase liquid chromatographic (RP-LC) separation techniques. MLC with the use of surfactant solutions above its critical micellar concentration (CMC) and the addition of organic modifiers is currently an important analytical tool with still growing theoretical considerations and practical applications in pharmaceutical analysis of drugs and other biologically active compounds. The use of MLC as an alternative, relatively much faster in comparison to conventional chromatographic separation techniques has several advantages, especially as being suitable for screening pharmaceutical analysis. The analytical data received from MLC analysis are considered a useful source of information to predict passive drug absorption, drug transport and other pharmacokinetics and physicochemical measures of pharmaceutical substances. In the review several MLC assays for determination of drugs and other active compounds in biological samples were compared and critically discussed. The presented overview provides information on recent applications and achievements connected with the practical use of MLC. The review covers fields of interest related to theory and mechanism of MLC separation, direct applications of MLC in pharmaceutical analysis, including optimization and efficiency of separation with the use of modification of stationary phase and mobile phase compositions as well as the determination of physicochemical characteristics of drugs by MLC. [...]

2

Impact of pharmaceutical dosage form on stability and dissolution of roxithromycin

81%

Ostrowski M., Wilkowska E., Bączek T.

Open Medicine

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2010

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vol. 5

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issue 1

83-90

EN

The behavior of dispersible tablets containing enteric-coated pellets and oral suspension, both containing roxithromycin, was investigated using dissolution tests in different media. The dissolution test was performed under different pH conditions. For both dosage forms investigated, the test was conducted at pH 1.2, 4.5, and 6.8. Additionally, for dispersible tablets, the test involving increasing pH was performed at pH 1.2 (acid stage) and afterwards at pH 6.8 (buffer stage). The extent of dissolution was measured using high-performance liquid chromatography (HPLC). In all cases tested, roxithromycin underwent rapid degradation at pH 1.2. Dispersible tablets displayed the features of modified release preparations with a non-complete dissolution during the test times in all media. Conversely, the oral suspension behaved as an immediate release preparation, with degradation at pH 1.2. However, the dissolution of the oral suspension at pH 4.5 and 6.8 was rapid and complete. The role of enteric-coated pellets is to mask the bitter taste of the active substance upon administration. However, the coating showed lack of resistance to media at pH 1.2. Therefore, dispersible tablets containing enteric-coated pellets are not pharmaceutically equivalent to the immediate-release oral suspension.

3

Is there any variability in the level of cortisol, corticosterone and cortisone of healthy volunteers versus women and men with elevated cholesterol?

81%

Konieczna L., Puch-Walczak A., Zdrojewski T., Bączek T.

European Journal of Translational and Clinical Medicine

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2021

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vol. 4

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issue 2

68-74

EN

Background: Cardiovascular diseases with the accompanied elevated level of total cholesterol have been a major problem in society for the last several decades. They belong to the diseases of civilization which affect people at an increasingly young age. For this reason, our aim was to investigate whether the concentrations of selected steroids are related to elevated total cholesterol in people without diagnosed cardiovascular diseases. Material and methods: The study involved 71 plasma samples. 19 of them were obtained from women and men with elevated cholesterol levels, whereas 52 samples were from healthy volunteers (control group). Liquid chromatography coupled with mass spectrometry (LC-MS) validated method followed by solid-phase extraction procedure were applied to measure the plasma concentrations of the three endogenous glucocorticosteroids (cortisol, corticosterone and cortisone). Results: Statistically significant differences between the concentration of cortisol were noted among healthy women and women with elevated cholesterol. The measured concentrations of cortisol in healthy women and men are comparable, 111.19 ng/mL and 112.22 ng/mL. respectively. However, the concentrations of cortisol in the elevated cholesterol group was significantly lower among women with elevated cholesterol than in healthy women (74.13 ng/mL and 111.19 ng/mL respectively). The concentration of cortisol for men with elevated cholesterol was 38.60 ng/mL. Hence, it is much higher than in women with elevated cholesterol and higher than in the case of healthy men. Distinctive changes can be observed also for corticosterone measured for both women and men. Conclusions: The observed differences on the level of steroids between healthy control group and patients with elevated cholesterol can be considered as worthy of further investigation from both biochemical as well as clinical points of view.

4

Determination of lipophilicity for antitumor acridinone derivatives supported by gradient high-performance liquid chromatography method

81%

Koba M., Belka M., Ciesielski T., Bączek T.

Open Chemistry

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2012

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vol. 10

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issue 1

216-223

EN

The lipophilicity values of selected acridinone (imidazoacridinone and triazoloacridinone) derivatives were measured by gradient reversed-phase high-performance liquid chromatography (RP-HPLC) using a C18 stationary phase with a water/acetonitrile mixture as a mobile phase. The retention times obtained served as input data and appropriate log kw values (i.e., the retention factor log kw extrapolated to 0% organic modifier) as an alternative to log P were calculated using the DryLab program. The relationships between the lipophilicity (log kw) and the chemical structure of the studied compounds, as well as correlation between experimentally determined lipophilicities (log kw) and log P data calculated using some commonly available software, are discussed.

5

Analytical methods for determination of benzodiazepines. A short review

71%

Szatkowska P., Koba M., Kośliński P., Wandas J., Bączek T.

Open Chemistry

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2014

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vol. 12

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issue 10

994-1007

EN

Benzodiazepines (BDZs) are generally commonly used as anxiolytic and/or hypnotic drugs as a ligand of the GABAA-benzodiazepine receptor. Moreover, some of benzodiazepines are widely used as an anti-depressive and sedative drugs, and also as anti-epileptic drugs and in some cases can be useful as an adjunct treatment in refractory epilepsies or anti-alcoholic therapy. High-performance liquid chromatography (HPLC) methods, thin-layer chromatography (TLC) methods, gas chromatography (GC) methods, capillary electrophoresis (CE) methods and some of spectrophotometric and spectrofluorometric methods were developed and have been extensively applied to the analysis of number of benzodiazepine derivative drugs (BDZs) providing reliable and accurate results. The available chemical methods for the determination of BDZs in biological materials and pharmaceutical formulations are reviewed in this work.

6

In Vitro approach for identification of a leading cytochrome P450 isoenzyme responsible for biotransformation of novel arylpiperazine drug candidates and their inhibition potency towards CYP3A4.

61%

Ulenberg S., Belka M., Georgiev P., Król M., Herold F., Bączek T.

Acta Poloniae Pharmaceutica - Drug Research

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2020

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vol. 77

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issue 1

69-76

EN

Presented article is a follow-up study of previous work, published in PLoS ONE in 2015 regarding metabolic stability of arylpiperazine derivatives, a very promising group of novel antidepressants. The aim of this study was to identify cytochrome P450 (CYP) isoforms that participate in the metabolism of some novel arylpiperazine derivatives developed by authors as well as their potency to inhibit reactions catalysed by identified lead metabolizing enzyme. Such studies allow to predict possible drug-drug interactions that might occur during co-administration of studied compounds with other drugs that are metabolized by identified enzyme. The compounds were incubated in vitro together with the isolated CYP isoforms. After the incubation, samples were analyzed by liquid chromatography coupled with mass spectrometry. The results showed main contribution of CYP3A4 isoform in biotransformation of the investigated derivatives. With CYP3A4 being the main CYP isoform responsible for the metabolism of arylpiperazine derivatives and at the same time being the main metabolizing enzyme for almost 50% of all drugs, a high chance of in vivo drug-drug interactions emerged. Therefore, IC50 values were also determined using testosterone hydroxylation as a probe reaction, specific for CYP3A4. The resulting values ranged from 6.13 to 15.85 µM, which places studied derivatives as moderate or weak inhibitors of CYP3A4. Those results, combined with conclusion that all of the arylpiperazine derivatives are also metabolized to some extent by other CYP isoforms (providing alternative metabolic pathways), result in conclusion that studied arylpiperazines might be safe for co-administration with other CYP3A4 substrates.

7

Prediction of antimicrobial activity of imidazole derivatives by artificial neural networks

52%

Wnuk M., Marszałł M., Zapęcka A., Nowaczyk A., Krysiński J., Romaszko J., Kawczak P., Bączek T., Buciński A.

Open Medicine

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2013

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vol. 8

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issue 1

1-15

EN

The main goal of our study is the analysis of data obtained from molecular modeling for a series of imidazole derivatives that possess strong antifungal activity. The research was designed to use artificial neural network (ANN) analysis to determine quantitative relationships between the structural parameters and anti-Streptococcus pyogenes activity of a series of imidazole derivatives. ANN in association with quantitative structure-activity relationships (QSAR) represents a promising tool in the search for drug candidates among the practically unlimited number of possible derivatives. In this work, a series of 286 imidazole derivatives presented as cationic three-dimensional structures was used. The activity was expressed as a logarithm of the reciprocal of the minimal inhibitory concentrations, log 1/MIC. Multilayer perceptron ANN was used for predictions of antimicrobial potency of new imidazole derivatives on the basis of their structural descriptors. The obtained correlation coefficient equaled 0.9461 for the learning set, 0.9060 for the validation set and 0.8824 for the testing set of imidazole derivatives. Hence, satisfactory and practically useful predictions of anti-Streptococcus pyogenes activity for a series of imidazole derivatives was obtained, supporting the future successful interpretation of QSAR analysis for those compounds.

Refine search results

Recent theoretical and practical applications of micellar liquid chromatography (MLC) in pharmaceutical and biomedical analysis

Impact of pharmaceutical dosage form on stability and dissolution of roxithromycin

Is there any variability in the level of cortisol, corticosterone and cortisone of healthy volunteers versus women and men with elevated cholesterol?

Determination of lipophilicity for antitumor acridinone derivatives supported by gradient high-performance liquid chromatography method

Analytical methods for determination of benzodiazepines. A short review

In Vitro approach for identification of a leading cytochrome P450 isoenzyme responsible for biotransformation of novel arylpiperazine drug candidates and their inhibition potency towards CYP3A4.

Prediction of antimicrobial activity of imidazole derivatives by artificial neural networks