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Viscoelastic properties of calcium hydrogenphosphate dihydrate of Emcopress
Hořínková, Pavla ; Řehula, Milan (advisor) ; Špaček, Vladimír (referee)
The important condition for materials compression are their viscoelastic properties. Two methods are used in this work for determination viscoelastic parameters of calcium hydrogephosphate dihydrate - the Creep test and the Stress relaxation test. Both methods provide us with elastic and plastic constants. During the Creep test the compaction pressure is kept constant for 180s and a decrease of tablet height is measured. This tablet decreasing allows us to calculate viscoelastic parameters. The most important result is the factor of total plasticity FPC, which is equal to 0,89441. The greater this value is the better compaction properties the material has. A constant height of tablet is held for 180s in the Stress relaxation test and a decrease of pressure within the tablet is recorded. This pressure decrease is caused by three different processes. The third process is most important for the tablet plasticity and is expressed by the total parameter of third process PSR3C = 328,86916 MPas. Again, the greater this value is the better compaction properties the material has.
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Physico-chemical characteritazion of microcrystalline celluloses
Gregor, Stanislav ; Řehula, Milan (advisor) ; Špaček, Vladimír (referee)
Charles Univerzity in Prague, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical technology Student: Mgr. Stanislav Gregor Supervisor: Doc. RNDr. Milan Řehula, CSc. Physico-chemical characteritazion of microcrystalline celluloses Microcrystalline cellulose is very important pharmaceutical excipient. The aim of the study was to evaluate the different types by using physico-chemical charakteristics. Particle size was evaluated by optical microscopy. The flow properties were evaluated by flowability and by the angle of repose. Bulk and tapped properties were evaluated by bulk and tap density and by compressibility index. Temperatute and heat of fusion, glass transitive temperature and specific heat improvers were evaluated by DSC. Compaction process was evaluated by compaction equations, stress relaxation test and record the force-displacement. The compressed tablets were evaluated by kinetics crushing tablets and had fixed radial strength. Particle sizes correspond to the declared values stated by the manufacturer. The largest deviation was found for Avicel PH-200 (difference 20,0 mm). With increasing particle size reduces fiction between particles and increases the flowability. The tapped density is higher than the bulk density and the copies. From the results of three- exponential...
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Characterization of Compaction Process According to New Equation Parameters of Compaction
Rysl, Tomáš ; Řehula, Milan (advisor) ; Špaček, Vladimír (referee) ; Rabišková, Miloslava (referee)
Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department: Department of galenic pharmacy Candidate: Mgr. Tomáš Rysl Supervisor: doc. RNDr. Milan Řehula CSc. Title of Doctoral Thesis: Characterization of compaction process according to new equation parameteres of compaction. The thessis deals with comparation of excipients used for production of tablets using new equations of tablet compaction. A lot of mathematical interpretations exist for determination of excipient behaviour during compaction process of tablet production. Obtained parameters of them express more or less possible behaviour of these excipients during compaction. The new mathematical interpretation was proposed for crystallic and polymeric materials. It seems to be very exact method to express compation process very correctly. 40 materials was evaluated according to this new proposed equation of compaction. Zwick/Roell Z050 was used to obtain this equation. Different behaviour of polymeric and crystallic materials has been found out. Behaviour of crystallic materials is interpreted by 2 phases, expressed by biexpoinencial equation. Behaviour of polymeric materials is interpreted by 3 phases, expressed by triexponencial equation. According to obtained paramateres, excipients have been described in term of...
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Physico-chemical characteritazion of microcrystalline celluloses
Gregor, Stanislav ; Řehula, Milan (advisor) ; Špaček, Vladimír (referee)
Charles Univerzity in Prague, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical technology Student: Mgr. Stanislav Gregor Supervisor: Doc. RNDr. Milan Řehula, CSc. Physico-chemical characteritazion of microcrystalline celluloses Microcrystalline cellulose is very important pharmaceutical excipient. The aim of the study was to evaluate the different types by using physico-chemical charakteristics. Particle size was evaluated by optical microscopy. The flow properties were evaluated by flowability and by the angle of repose. Bulk and tapped properties were evaluated by bulk and tap density and by compressibility index. Temperatute and heat of fusion, glass transitive temperature and specific heat improvers were evaluated by DSC. Compaction process was evaluated by compaction equations, stress relaxation test and record the force-displacement. The compressed tablets were evaluated by kinetics crushing tablets and had fixed radial strength. Particle sizes correspond to the declared values stated by the manufacturer. The largest deviation was found for Avicel PH-200 (difference 20,0 mm). With increasing particle size reduces fiction between particles and increases the flowability. The tapped density is higher than the bulk density and the copies. From the results of three- exponential...
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Monosaccharides and disaccharides classification by Creep testing Mehod
Frýdlová, Dana ; Řehula, Milan (advisor) ; Špaček, Vladimír (referee)
- EN The name of study: Monosaccharides and disaccharides classification by Creep testing Method Student: Mgr. Dana Frýdlová Tutor: Doc. RNDr. Milan Řehula, CSc. Consultant: Mgr. Roman Adámek Department of Pharmaceutical Technology, Faculty of Pharmacy in Hradec Kralove, Charles University in Prague, Czech Republic Background: The whole process of tablet compression is depended on viscoelastic properties of fillers. Terms plasticity and elasticity are not clearly defined. In this area, their interpretation results from a method which is applied. Aim: In this study the Creep test was used for classification of viscoelastic properties of following fillers: sorbitol, manitol, saccharose, Tabletose and anhydrous lactose. Methods: Measurement was realized by a special apparature T1 - FRO 50 (producer: Zwick GmbH and Co, Ulm, Germany) and the compaction process was recorded by a special software, which was connected to the compressing device. Obtained data were processed by Origin Professional 7.5 and Microsoft Excel. Results: Monosaccharides were found to be more plastic and more pressable than disaccharides. The most plastic material was mannitol. Disacharides were more elastic than monosaccharides. Tabletose was the most elastic material. Anhydric form of lactose was more plastic than its monohydric...
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Influence of Skid Substances to Compression Equations Parameters
Linková, Markéta ; Řehula, Milan (advisor) ; Špaček, Vladimír (referee)
Mgr.Markéta Linková The rigorous assignment Influence of Skid Substances to Compression Equations Parameters Abstract The rigorous assignment engages in impact of skid substances on parameters of compression equations. Parameters of compression equations are used for compressed material characteristic and for study of compression process mechanism. The mostly used compression equations are described in the theoretic part. Additionally are analyzed factors, which have influence to the parameters of compression equations. (For example: particles size, material type, compression speed) Target of experiment was to prove influence of skid substances to parameters of compression equations. As a skid substances has been used magnesi stearat and talc. Compression process is possible to evaluate through parameters AR, LT, E, EP. For calculation of polymers on cellulose basis the three - exponential equation has been used. For crystallic substances two - exponential equation has been used. Final results prove that both skid substances had same impact to parameters of compression equations.
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Evaluation of Celluloses and Maize Starch by the Creep Test Method
Doležalová, Julie ; Řehula, Milan (advisor) ; Špaček, Vladimír (referee)
Evaluation of Celluloses and Maize Starch by the Creep Test Method The aim of this work was to consider the appropriateness of using the creep test for evaluation of visco-elastic characteristics of pharmaceutical fillers and to compare these properties. Pharmaceutical powders involved in this assessment were powdered cellulose (Vitacel A 300), hydroxyethylcellulose (HEC, Natrosol 250), hydroxypropylcellulose (HPC, Klucel EF), hydroxypropylmethylcellulose (HPMC, K 100) and maize starch. The powders were compressed with a material-testing machine T1-FRO 50 by compression forces of 0,25; 0,5; 1; 2; 3; 4; 5; 7,5; 10 and 15 kN. Compression data for each tablet were then recorded by a software connected to the compressing machine. The recorded data, such as die displacement and time, were transferred into relation between creep compliance (J) and time. Obtained values were then used for calculating the parameters such as immediate elasticity (E1), retarded elasticity (E2), plasticity (P1) and factor of plasticity (FP). To summarize all results, we can say that hydroxypropylcellulose has the highest values of elasticity and the lowest values of plasticity among all tested powders. Conversely hydroxypropylmethylcellulose shows the lowest elasticity and powdered cellulose presents the most plastic...
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The Viscoelasticity of Pharmaceutical Fillers for Direct Tabletting
Adámek, Roman ; Řehula, Milan (advisor) ; Rabišková, Miloslava (referee) ; Špaček, Vladimír (referee)
Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical technology Candidate: Mgr. Roman Adámek Supervisor: Doc. RNDr. Milan Řehula, CSc. Title of Doctoral Thesis: Viscoelasticity of fillers for direct tablet compacting Keywords: stress relaxation, viscoelasticity, Maxwell-Wischert model, hydrogen bond, van der Waals bond Important property of pharmaceutical fillers is viscoelasticity which can be evaluated in many ways. The Stress relaxation test is a method when a punch of compacting machine stops precisely in a moment of reaching set up pressure and decreasing pressure in a tablet during time is recorded. This action is mathematically described by a three-exponential equation which facilitates to separate the Stress relaxation test in three simultaneously running actions. Each of these actions is described by the moduli of plasticity and elasticity which point out in detail on viscoelastic properties of measured materials. The Stress relaxation test was used for 20 pharmaceutical fillers by 11 compacting pressures. To infer clearer conclusions, tablet strength, Young's modul of elasticity and elastic potential energy were determined. With help of above mentioned compacting parameters conclusions of viscoelasticity and compacting properties of used...
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Characterization of Compaction Process According to New Equation Parameters of Compaction
Rysl, Tomáš ; Řehula, Milan (advisor) ; Špaček, Vladimír (referee) ; Rabišková, Miloslava (referee)
Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department: Department of galenic pharmacy Candidate: Mgr. Tomáš Rysl Supervisor: doc. RNDr. Milan Řehula CSc. Title of Doctoral Thesis: Characterization of compaction process according to new equation parameteres of compaction. The thessis deals with comparation of excipients used for production of tablets using new equations of tablet compaction. A lot of mathematical interpretations exist for determination of excipient behaviour during compaction process of tablet production. Obtained parameters of them express more or less possible behaviour of these excipients during compaction. The new mathematical interpretation was proposed for crystallic and polymeric materials. It seems to be very exact method to express compation process very correctly. 40 materials was evaluated according to this new proposed equation of compaction. Zwick/Roell Z050 was used to obtain this equation. Different behaviour of polymeric and crystallic materials has been found out. Behaviour of crystallic materials is interpreted by 2 phases, expressed by biexpoinencial equation. Behaviour of polymeric materials is interpreted by 3 phases, expressed by triexponencial equation. According to obtained paramateres, excipients have been described in term of...
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