David Vetchý

University of Veterinary and Pharmaceutical Sciences Brno, Brünn, South Moravian, Czech Republic

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Publications (58)37.79 Total impact

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    ABSTRACT: Objectives: The aim of the study was to use methods of pharmaceutical technology, and prepare carriers in the form of pellets suitable as a filling of detection tubes for enzymatic detection of cholinesterase inhibitors. The enzymatic detection was based on enzymatic hydrolysis of acetylthiocholine iodide and the subsequent colour reaction of its hydrolysis product with Ellman's reagent. The suitable carriers should be in the form of white, regular and sufficiently mechanically resistant particles of about 1 mm allowing it to capture the enzyme during the impregnation process and ensuring its high activity for enzymatic detection. Methods: Carriers consisting of microcrystalline cellulose, lactose, povidone, and sodium carboxymethyl cellulose were prepared using extrusion-spheronization method under three different drying conditions in either a hot air oven or a microwave oven. Subsequently, the carriers were impregnated with acetylcholinesterase and their size, shape, mechanical resistance, bulk, tapped and pycnometric density, Hausner ratio, intraparticular and total tapped porosity, and activity were measured and recorded. Results: In this procedure, carriers with different physical parameters and different acetylcholinesterase activity were evaluated. It was found that higher acetylcholinesterase activity was associated not only with a higher intraparticular porosity but also with more regular particles characterized by high sphericity and low total tapped porosity. Conclusion: This unique finding is important for the preparation of detection tubes based on enzymatic detection which is still irreplaceable especially in the field of detection and analysis of super-toxic cholinesterase inhibitors.
    No preview · Article · Jan 2016 · Neuro endocrinology letters
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    ABSTRACT: Infectious stomatitis represents the most common oral cavity ailments. Current therapy is insufficiently effective because of the short residence time of topical liquid or semisolid medical formulations. An innovative application form based on bioadhesive polymers featuring prolonged residence time on the oral mucosa may be a solution to this challenge. This formulation consists of a mucoadhesive oral film with incorporated nanocomposite biomaterial that is able to release the drug directly at the target area. This study describes the unique approach of preparing mucoadhesive oral films from carmellose with incorporating a nanotechnologically modified clay mineral intercalated with chlorhexidine. The multivariate data analysis was employed to evaluate the influence of the formulation and process variables on the properties of the medical preparation. This evaluation was complemented by testing the antimicrobial and antimycotic activity of prepared films with the aim of finding the most suitable composition for clinical application. Generally, the best results were obtained with sample containing 20 mg of chlorhexidine diacetate carried by vermiculite, with carmellose in the form of nonwoven textile in its structure. In addition to its promising physicomechanical, chemical, and mucoadhesive properties, the formulation inhibited the growth of Staphylococcus and Candida; the effect was prolonged for tens of hours.
    Full-text · Article · Jun 2015 · BioMed Research International
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    Barbora Vraníková · Jan Gajdziok · David Vetchý
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    ABSTRACT: Liquisolid systems are an innovative dosage form used for enhancing dissolution rate and improving in vivo bioavailability of poorly soluble drugs. These formulations require specific evaluation methods for their quality assurance (e.g., evaluation of angle of slide, contact angle, or water absorption ratio). The presented study is focused on the preparation, modern in vitro testing, and evaluation of differences of liquisolid systems containing varying amounts of a drug in liquid state (polyethylene glycol 400 solution of rosuvastatin) in relation to an aluminometasilicate carrier (Neusilin US2). Liquisolid powders used for the formulation of final tablets were prepared using two different methods: simple blending and spraying of drug solution onto a carrier in fluid bed equipment. The obtained results imply that the amount of liquid phase in relation to carrier material had an effect on the hardness, friability, and disintegration of tablets, as well as their height. The use of spraying technique enhanced flow properties of the prepared mixtures, increased hardness values, decreased friability, and improved homogeneity of the final dosage form.
    Full-text · Article · Jun 2015 · BioMed Research International
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    ABSTRACT: Effective assessment and management of wound pain can facilitate both improvements in healing rates and overall quality of life. From a pharmacological perspective, topical application of nonsteroidal anti-inflammatory drugs in the form of film wound dressings may be a good choice. Thus, the aim of this work was to develop novel layered film wound dressings containing ibuprofen based on partially substituted fibrous sodium carboxymethylcellulose (nonwoven textile Hcel NaT). To this end, an innovative solvent casting method using a sequential coating technique has been applied. The concentration of ibuprofen which was incorporated as an acetone solution or as a suspension in a sodium carboxymethylcellulose dispersion was 0.5 mg/cm 2 and 1.0 mg/cm 2 of film. Results showed that developed films had adequate mechanical and swelling properties and an advantageous acidic surface pH for wound application. An in vitro drug release study implied that layered films retained the drug for a longer period of time and thus could minimize the frequency of changing the dressing. Films with suspended ibuprofen demonstrated higher drug content uniformity and superior in vitro drug release characteristics in comparison with ibuprofen incorporation as an acetone solution. Prepared films could be potential wound dressings for the effective treatment of wound pain in low exuding wounds.
    Full-text · Article · May 2015 · BioMed Research International
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    D. Sabadková · A. Franc · J. Muselík · D. Neumann · D. Vetchý
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    ABSTRACT: This review is focused on the basic principles of the delivery systems with a pulsatile release pattern. Such systems are designed according to the circadian rhythm of the body. Time-controlled, stimuli-induced and externally regulated pulsatile drug delivery systems are recognized. The drug release of time-controlled systems occurs after a predefined time lag. Stimuli-induced systems release the drug as a reaction to changeable conditions in the body (pH, glucose level). The drug release of externally regula¬ted systems is controlled via external stimulus (magnetism, ultrasound). Pulsatile drug delivery systems rank among modern dosage forms which provide many therapeutic benefits. © 2015, Czech Society of Chemical Engineering. All Rights Reserved.
    Full-text · Article · May 2015 · Chemicke Listy
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    ABSTRACT: Flavonol (−)-epicatechin and its derived dimer procyanidin B2, present in high amounts in cocoa products, have been shown to exert beneficial effects on the heart and cardiovascular system; however, their mechanism of action has not been fully elucidated. We studied effects of (−)-epicatechin and procyanidin B2 on the oxidative phosphorylation of isolated rat heart mitochondria. (−)-Epicatechin and procyanidin B2 had stimulating effect (up to 30% compared to control) on substrate-driven (State 2) mitochondrial respiration. Their effect was dependent on the respiratory substrates used. (−)-Epicatechin at higher concentrations (from 0.27 µg/mL) significantly decreased (up to 15%) substrate- and ADP-driven (State 3) mitochondrial respiration in case of pyruvate and malate oxidation only. Procyanidin B2 (0.7–17.9 ng/mL) inhibited State 3 respiration rate up to 19%, the most profound effect being expressed with succinate as the substrate. (−)-Epicatechin at concentrations of 0.23 µg/mL and 0.46 µg/mL prevented loss of the cytochrome c from mitochondria when substrate was succinate, supporting the evidence of membrane stabilizing properties of this flavonol. Thus, both (−)-epicatechin and procyanidin B2 directly influenced mitochondrial functions and the observed effects could help to explain cardiometabolic risk reduction ascribed to the consumption of modest amounts of cocoa products.
    Full-text · Article · Feb 2015
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    E. Mašková · K. Kubová · D. Vetchý
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    ABSTRACT: Eudragit® polymers are widely used acrylic pharmaceutical excipients. Over recent years, they have often been applied in matrix tablets with controlled drug release to improve the therapeutic activity and patient compliance. Eudragit® polymers can be used alone or combined with other poly(meth)acrylates or cellulose derivatives (hypromellose, ethylcellulose). Generally, Eudragit® matrices contain a soluble (lactose) or an indifferent filler (microcrystalline cellulose). Eudragit/s® is incorporated into matrix tablets to achieve a drug dissolution profile close to zero-order kinetics or the pH-independent release of a drug with pH-dependent solubility. Properties and dissolution behavior of Eudragit® matrices can be influenced by their thermal treatment. © 2015, Czech Society of Chemical Engineering. All rights reserved.
    Full-text · Article · Jan 2015 · Chemicke Listy
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    ABSTRACT: Abstract The main objective of this study was to evaluate the influence of the formulation and process parameters on PLGA microparticles containing a practically insoluble model drug (ibuprofen) prepared by the o/w solvent evaporation method. Multivariate data analysis was used. The effects of altered stirring speed of a mechanical stirrer (600, 1000 rpm), emulsifier concentrations (PVA concentration 0.1 %, 1 %) and solvent selection (dichloromethane, ethyl acetate) on microparticle characteristics (encapsulation efficiency, drug loading, burst effect) were observed. It was found that with increased stirring speed, the PVA concentration or the use of ethyl acetate had a significantly negative effect on encapsulation efficiency. In addition, ethyl acetate had an adverse effect on the burst effect, while increased stirring speed had the opposite effect. Drug load was not affected by any particular variable, but rather by the interactions of evaluated variables.
    Full-text · Article · Dec 2014 · Acta Pharmaceutica
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    ABSTRACT: Hypoglycemic episodes are a frequent and serious complication in both types of diabetes mellitus. The risk of hypoglycemic conditions can be managed by a coated pellet dosage form, which can release glucose in a delayed regime to achieve the maximum estimated effect of antidiabetics. The pellet cores, intended for coating with ethylcellulose, were prepared consisting of four osmotically active excipients: crosscarmellose (Ac-Di-Sol®), a mixture of microcrystalline cellulose and carmellose sodium (Avicel® RC 591), carboxymethyl starch sodium (Vivastar® P 5000) and macrogol 6000, respectively. The aim of this study was to increase the glucose content in the pellets to minimize their volume and to improve the administration to the patients. The content of glucose in the pellet cores was increased from 45 to 75 or 80%, respectively, for all compositions. All pellet samples had satisfactory mechanical and flow properties required for the coating process. The highest values of sphericity were achieved in the lower mean particle size sample containing 80% of glucose, 15% of Avicel® PH 101 and 5% of carboxymethyl starch sodium and the higher mean particle size sample containing 75% of glucose and 25% of Avicel® RC 591.Key words: hypoglycemia - delayed release - glucose.
    Full-text · Article · Oct 2014 · Ceská a Slovenská farmacie: casopis Ceské farmaceutické spolecnosti a Slovenské farmaceutické spolecnosti
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    ABSTRACT: This experimental study describes the preparation of a veterinary medicated premix containing tetracycline hydrochloride for oral administration to aquatic animals. For the manufacture of the premix, commercially produced animal feed is used, which is intended for consumption in the form of pellets that were coated with a mixture of chlortetracycline hydrochloride and other excipients. Feed pellets were combined with a mixture of an active substance and excipients with a large specific surface (colloidal silica - Aerosil® 200) allowing an easy adhesion to the surface of the pellets, and a solid polymer with a low glass transition point (Eudragit® E) which ensures the formation of a hard coat. A mixture of these substances has been applied to the surface of the pellets either A) in the solid state simply by dry adhesion; B) by coating the pellets with the mixture and additional impregnation with ethanol; or C) the polymer was subsequently applied in solution. In the final stage, the pellets were heated in order to achieve the glass transition point of the polymer to create a solid and mechanically resistant coating. Coated pellets prepared by three methods described above are almost identical in their physical properties. With this technology it is possible to produce a feed mixture with a very low content of the active substance in situ without the need for a complex technological equipment.Keywords: medicated feed premix pellets impregnation adhesion fish.
    No preview · Article · Oct 2014 · Ceská a Slovenská farmacie: casopis Ceské farmaceutické spolecnosti a Slovenské farmaceutické spolecnosti
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    ABSTRACT: Liphophilic formulations of pharmaceuticals are very promising methods of drug solubility improvement. Four types of the formulations are available: Self-emulsifying drug delivery systems (SEDDS) consist of oils, surfactants and cosolvents where the pharmaceutical ingredient are dissolved. These systems form o/w emulsions which can be administered in tablets, soft or hard gelatin capsules. The effectivity of SEDDS depends on many parameters, such as excipients or emulsion droplet size. © 2014 Czech Society of Chemical Engineering. All rights reserved.
    No preview · Article · Oct 2014 · Chemicke Listy
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    ABSTRACT: Oral mucosa is an attractive region for the local and systemic application of many drugs. Oral mucoadhesive films are preferred for their prolonged time of residence, the improved bioavailability of the drug they contain, their painless application, their protection against lesions, and their nonirritating properties. This work was focused on preparation of nonmedicated carmellose-based films using both solvent casting and impregnation methods, respectively. Moreover, a modern approach to evaluation of mucoadhesive films applying analysis of texture and subsequent multivariate data analysis was used. In this experiment, puncture strength strongly correlated with tensile strength and could be used to obtain necessary information about the mechanical film characteristics in films prepared using both methods. Puncture work and tensile work were not correlated in films prepared using the solvent casting method, as increasing the amount of glycerol led to an increase in the puncture work in thinner films. All measured texture parameters in films prepared by impregnation were significantly smaller compared to films prepared by solvent casting. Moreover, a relationship between the amount of glycerol and film thickness was observed, and a greater recalculated tensile/puncture strength was needed for an increased thickness in films prepared by impregnation.
    Full-text · Article · Jul 2014 · BioMed Research International
  • Barbora Vraníková · Jan Gajdziok · David Vetchý
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    ABSTRACT: Abstract Context: Liquisolid systems are modern formulations used to increase the bioavailability of poorly water-soluble drugs. Their preparation is based on the sorption of a drug in liquid state onto a carrier with a high adsorption capacity. The carrier particles are subsequently coated with material having a large surface area to form free-flowing powder. The main principle of bioavailability increasing is based on the presence of the dissolved drug, which is ready for immediate absorption in GI tract. Objective: Determination of capability of aluminometasilicate carrier Neusilin® US2 to adsorb different solvents. Materials and methods: The maximum amounts of polyethylene glycol 200 (PEG 200), polyethylene glycol 400 and propylene glycol (PG), which can be sorbed by Neusilin® US2, while maintaining an acceptable flowability of the powder mixture, were evaluated using determination of the flowable liquid retention potential. Results and discussion: From the evaluation of liquisolid powder mixtures, it could be observed that 1 g of Neusilin® US2 can retain up to 1.00 g of PG, 1.16 g of polyethylene glycol 400 and 1.48 g of PEG 200, while maintaining acceptable flowing properties. Conclusion: Large specific surface area in combination with a high absorption capacity makes Neusilin® US2 suitable carrier for liquisolid system preparation.
    No preview · Article · Jun 2014 · Pharmaceutical Development and Technology
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    ABSTRACT: Essential oil of the Siberian fir (Abies sibirica Ledeb.) ranks among the substances with potential use in prevention and treatment of oral candidiasis. Therefore, the aim of the study was the formulation, preparation and evaluation of an oral gel containing 0.3% of this essential oil. Carbopol 974P NF in 1% concentration was used as the gelling agent, some samples were additionally stabilized by an addition of polysorbate 80 (0.1-0.5%). Xylitol in concentrations of 10% or 20% was added with the aim to modify the taste properties of the gel. Following microscopic evaluation (mean oil droplet size, degree of dispersity) immediately after preparation and after 6-month storage, it has been found that the optimal concentration of polysorbate 80 is 0.3%. The results of the experiment also demonstrated that xylitol was not only an excipient adjusting the organoleptic properties of the preparation - its use enabled significant improvement of the quality parameters and stability.
    Full-text · Article · Jun 2014 · Ceská a Slovenská farmacie: casopis Ceské farmaceutické spolecnosti a Slovenské farmaceutické spolecnosti
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    ABSTRACT: The aim of this experimental study was to optimize a preparation of microspheres from high viscosity chitosan by external ion gelation and to evaluate selected aspects of their preparation. For drug-free microparticles, the concentration of chitosan dispersions was chosen as a formulation variable; the position of instrument for a dispersion extrusion (horizontal vs. vertical) was evaluated as a process variable. On the basis of sphericity and equivalent diameter results, three different concentrations of chitosan dispersions were used for 5-aminosalicylic acid (5-ASA) encapsulation with the extrusion instrument in horizontal position, which was considered as the optimal. In consequent drug-loaded microparticle preparation, the influence of the concentration of chitosan dispersions and composition of hardening solution (10% sodium tripolyphosphate (TPP) vs. 10% TPP containing drug) was evaluated. In prepared 5-ASA microspheres it was found that the equivalent diameter increased with increasing chitosan concentration. In the case of sphericity, significant differences were not found. Samples prepared with the drug in both chitosan dispersion and hardening solution had a higher drug content, a smaller equivalent diameter and they showed a faster in vitro drug release in comparison with the samples prepared with the drug in chitosan dispersion only.
    Full-text · Article · Jun 2014 · Ceská a Slovenská farmacie: casopis Ceské farmaceutické spolecnosti a Slovenské farmaceutické spolecnosti
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    ABSTRACT: Unlabelled: This study aimed to prepare high molecular weight chitosan blank and drug-loaded microparticles using 5-aminosalicylic acid (5-ASA) as the model active substance by an external ionic gelation. Formulation and process variables included the chitosan concentration and presence of drug in the polymer solution, and/or in hardening solution during the microparticles preparation. The effect of different preparation conditions on the properties of the microparticles was observed with a view to increase drug content in microparticles. For both types of microparticles (with and without the drug), it was found that their sphericity and equivalent diameter increased with increasing chitosan concentration. The drug content of drug-loaded microparticles was the highest in the case of the sample prepared from 1.75% chitosan dispersion, when the drug was present both in the chitosan dispersion and the hardening solution. Maximum six times higher drug content was achieved by change of the placement of 5-ASA during preparation (1.25% chitosan concentration). Keywords: microparticles external ionotropic gelation chitosan 5-ASA encapsulation efficiency.
    Full-text · Article · Apr 2014 · Ceská a Slovenská farmacie: casopis Ceské farmaceutické spolecnosti a Slovenské farmaceutické spolecnosti
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    ABSTRACT: A new simple and sensitive detection tube to detect hydrogen cyanide in the air has been developed. The detection tube is based on the reaction of hydrogen cyanide with 4-nitrobenzil to form a violet colored product. The reaction takes place on a carrier made of a composite material, which was prepared by pelletization of a mixture of microcrystalline cellulose and MgO. The detection tube can detect hydrogen cyanide in the air in the range of concentrations 0.1-100 mg m-3 based on visual evaluation (by naked eye) of the change of indication layer coloring and comparison with etalon. The detection limit is 0.05 mg m-3. The detection tube is highly selective and sufficiently stable during storage.
    Full-text · Article · Apr 2014 · Chemical Industry and Chemical Engineering Quarterly
  • D. Vetchý · M. Kopecká · M. Vetchá · A. Franc
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    ABSTRACT: Many experiments were performed to obtain in vitro - in vivo correlations for different drugs and formulations. Most of the correlations involve orally administered medical forms and those with prolonged release of the drug. Most of the informative and recommendable in vitro - in vivo correlations are those at level A. If the correlation is not possible, a multiple correlation at level C is performed, then those at levels C and B and finally the correlation at level D. The drug dissolution data correlate well with those of drug absorption in the case of establishing the correlation at level A. Although many correlations at levels B and C were weak, good correlations could be also obtained. For immediate release preparations, correlation at level A is recommended. Correlations at level C are appropriate providing especially for preparations with immediate release of the drug, where it is difficult to establish a correlation at level A. Multiple correlations at level C are acceptable and comparable with those at level A IVIVC, but are not suitable for products with immediate release of the drug.
    No preview · Article · Jan 2014 · Chemicke Listy
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    ABSTRACT: Texture analysis as a versatile tool for testing the inner structure of materials have been widely used. Though being also used in pharmaceutical industry, it has not been included in standard procedures for evaluation of drug dosage forms. The aim of this study is to measure the thickness of gel layer using texture analysis for the prediction of dissolution profile of very soluble drugs based on hydrophilic and hydrophilic-lipophilic matrix tablets. For the evaluation of the correlation between the thickness of the gel layer as an independent variable and the amount of a released drug as a dependent variable at given time intervals, the multivariate method of partial least squares – PLS-2 regression was used. For the prediction of dissolution characteristics of matrix tablets, a PLS-2 model validated by full cross-validation was developed. A PLS-2 model validated by full cross-validation was developed.
    Full-text · Article · Jan 2014 · Chemicke Listy
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    ABSTRACT: Mucoadhesive films represent the most developed medical form of buccal application. Despite the intense focus on buccal film-based systems, there are no standardized methods for their evaluation, which limits the possibility of comparison of obtained data and evaluation of the significance of influence of formulation and process variables on properties of resulting films. The used principal component analysis, together with a partial least squares regression provided an unique insight into the effects of in vitro parameters of mucoadhesive buccal films on their in vivo properties and into interdependencies among the studied variables. In the present study eight various mucoadhesive buccal films based on mucoadhesive polymers (carmellose, polyethylene oxide) were prepared using a solvent casting method or a method of impregnation, respectively. An ethylcelullose or hydrophobic blend of white beeswax and white petrolatum were used as a backing layer. The addition of polyethylene oxide prolonged the in vivo film residence time (from 53.24 ± 5.38 - 74.18 ± 5.13 min to 71.05 ± 3.15 - 98.12 ± 1.75 min), and even more when combined with an ethylcelullose backing layer (98.12 ± 1.75 min) and also improved the film's appearance. Tested non-woven textile shortened the in vivo film residence time (from 74.18 ± 5.13 - 98.12 ± 1.75 min to 53.24 ± 5.38 - 81.00 ± 8.47 min) and generally worsened the film's appearance. Mucoadhesive buccal films with a hydrophobic backing layer were associated with increased frequency of adverse effects.
    No preview · Article · Dec 2013 · European journal of pharmaceutics and biopharmaceutics: official journal of Arbeitsgemeinschaft fur Pharmazeutische Verfahrenstechnik e.V