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Viscoelastic properties of microcrystalline cellulose of Avicel PH 200
Skálová, Marie ; Řehula, Milan (advisor) ; Špaček, Vladimír (referee)
In this dissertation the viscoelasticity of the most common excipient microcrystaline celulose was valuated and viscoelasticite parametres were compared to three substances. Viscoelasticity was valuated by two methods..The first method is Creep test. In this analyze the compression force is constant and hold for 180s. During this time height of the tablet was lowered. The diffrences of tablet height was noted and used for calculation in Crčel test. Parameters of elasticity got by this method are FCT1,FCT2 and parameters of plasticity are PCT1,FP. When the parameters of elasticity increase the elasticity decrease. When the parameter FP increases the plasticity increases too. The higher the value of PCT1 is the lower is the plasticity. Stress relaxation is the second method. In this analyze hight of tablet is constant and decline compression force is recorded. In this analyze we noted the decline for 180 sec. In this way we get parameters of elasticity ESR1, ESR2, ESR3 and parameters of plasticity PSR1, PSR2, PSR3. The plasticity increases when parameter P increases. Comparing three substances the elasticity increases in-line Emcompress, Avicel, Flowlac and the elasticity decreases in-line Emcompress, Avicel, Flowlac.
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Determining the compression behaviour of hypromelloses.
Palounková, Zuzana ; Řehula, Milan (advisor) ; Špaček, Vladimír (referee)
The diploma work is concerned with a study of mechanical resistance which is assessed through the tablet crushing force and tensile strenght.In this work there was used tablet measuring method resulting from the recording of force - path, while the crushing process is assessed not only by crushing strenght but also by the path of crushing. Using the crushing force, crushing path and tablet crushing force is possible to compute next parameteres of crushing process detailing tablet properties as are volume crushing force, volume crushing energy and weight crushing energy. Assessed tablets were compacted of microcrystalline cellulose, hydroxypropylmethylcelulos, lactose and calcium hydrogen phosphate. From the result of work follows that crushing force (possibly tensile strenght) is decreasing in assessed adjuvants microcrystalline cellulose Ceolus, hydroxypropylmethycellulose HPMC K4, hydroxypropymethylcellulose HPMC K100, calcium hydrogen phosphate Emcompress, lactose Tablettosa respectively. Tablet breakage kinetics parameteres were decreasing with used substances in order microcrystalline cellulose Ceolus, hydroxypropymethylcellulose HPMC K100, hydroxypropylmethycellulose HPMC K4, and the lowest results were registered with lactose Tablettossa and calcium hydrogen phosphate Emcompress.
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Evaluation of compressibility of ibuprofen
Kolarczyková, Barbora ; Řehula, Milan (advisor) ; Svačinová, Petra (referee)
The aim of this study is to determine whether dissociation and a change of crystal modification of ibuprofen do not arise during the compression process. For this purpose an evaluation by means of equation of compression, evaluation by stress relaxation, evaluation by force-distance diagram and evaluation by differential scanning calorimetry is accomplished. The equation of compression developed by department of pharmaceutical technology describes the process of compression by parameters of three phases: phase before compression, phase elastic and plastic deformation. The test of stress relaxation was performed at compression force of 5, 10 and 15 kN. During the evaluation of a force-distance record phase of compression and relaxation of tablet was examined from energetic point of view at compression force of 5, 10, 15, 20, 25, 30, 35, 40 kN. These tablets were also evaluated by means of differential scanning calorimetry. Two basic conclusions arise out of the measured results: during the compression process dissociation or modification of crystal form if ibuprofen and simultaneously low plasticity of medicinal substance was found out (at compression force of 15kN plasticity was only 47 %).
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Determining the plasticity of lactose
Patočková, Simona ; Řehula, Milan (advisor) ; Špaček, Vladimír (referee)
The aim of this work was to take charakteristic of lactose and their influence on compressibility. Plastic properties ensuring better compressibility of material, whereas elastic properties make difficult for compressibility. Plasticity and elasticity are important characteristics of compacting materials. Several methods are commonly used for calculation of these parameters. One of the methods utilizes elastic recovery. On the base of relation between elastic recoveries and compression pressure, the Young's modul of elasticity is counted. Elastic and plastic energy is acquired from measurement force - displacement representing continuance of pressing process. Force - displacement curves are obtained from measurements of punch force and displacement. Energy is needed for the compression of material and formation of strong compacts. The properties of the compact are correlated with the energy input. The force - displacement profiles as such may be useful as a material charakteristic. Furthermore, the stress relaxation test is exploited for calculation of plasticity. By this test the parameters F min A, F min B, FPL and also characteristics of single parametric relation dependence of compacting pressure on time are counted. In this work, the lactose was evaluated by all mentioned methods. The basic...
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Evaluation of compressibility of acetylsalicylic acid
Pavelková, Petra ; Řehula, Milan (advisor) ; Svačinová, Petra (referee)
Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Student: Petra Pavelková Consultant: Doc. RNDr. Milan Řehula, CSc. Evaluation of compressibility of acetylsalicylic acid The aim of this thesis was evaluation of stability of acetylsalicylic acid from crystallographic aspect during compression process and to determine compressibility of this medical substance in the same time. For this purpose it was performed measurement of differential scanning calorimetry in range from - 30 žC to 220 žC by a speed of heating 10 žC/min. and cooling - 20 žC/min.. Further, the compaction equation, force-displacement record at compression forces ranging from 5 to 40 kN, and the stress relaxation at compression forces of 5, 10 and 15 kN were used. Measurement took place in specific conditions, which are described below. The experimental results showed following conclusions: The relation between the parameter E3 and compression force (LS) is non- linear and described by the equation: ESD3 = 0,086 LS + 0,013 LS2 - 0,211 R2 = 0,9999 The relation between plasticity and compression force (LS) is also non-linear and described by the equation: Pl = - 3,603 LS + 0,049 LS2 + 85,506 R2 = 0,9903 Values of the parameter PL show that ASA has a poor compressibility. At a...
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Evaluation and optimisation of a granulation process on a laboratory scale fluid bed granulator.
Stoniš, Jan ; Mužíková, Jitka (advisor) ; Řehula, Milan (referee)
The fluid bed granulation is a well-established method how to improve such properties of powders as flowability and increase content uniformity of the tablets. In this thesis, there was evaluated a granulation process on a lab scale fluid Glatt bed granulator and optimized for highest possible yield. Product yield in the size range of 80-90 % of granules and process reproducibility were stated as most effective. The product was analysed for its particle size distribution, the API distribution within the different particle size fractions and the flowability of the final granules. For process optimization, the most critical parameters such as spraying rate, particle size of raw materials and fluid bed pressure were identified and evaluated. As the highest-yielding dosage for the powder binder was found the spraying rate of 9 g/min. Changes in bed fluid pressure and nozzle pressure showed no significant improvement. Different grades of caffeine were compared for their impact on the granulation properties. Sieved caffeine enhanced yield of the product and reproducibility compared to bulk or disagglomerated caffeine.
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Determination of the Kinetics of the Crushing Process of Tablets Containing Isosorbide-5-mononitrate
Šulková, Petra ; Řehula, Milan (advisor) ; Musilová, Marie (referee)
Šulková Petra - diplomová práce - 2006 The diploma theses deal with the determination of optimal parameters for measurement of the kinetics of destruction on basis of force - displacement record. Theoretical part of the work discusses questions of fillers in direct tablet compression. It describes lactose in detail. Besides it describes the methods of evaluation of mechanical resistance of tablets and parameters destructive process. The aim of the experimental work was the evaluation of the destructive process by differential method without zero setting. The minimum value of preloading and cycle rate was to be determined. The tablets of Isosorbit-5-mononitrate were evaluated. The result of the work was the determination of the optimal parameters for the measurement of mechanical resistance of tablets by means of T1 - FRO 50. Minimum value of preloading is 0.1 N, cycle rate and preloading rate 1.0 mm/s. Simultaneously, it was found out that the decrease in force does not influence destructive force, displacement and energy.
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Determining the compression behaviour of microcrystalline cellulose and magnesium stearate
Smékalová, Petra ; Řehula, Milan (advisor) ; Špaček, Vladimír (referee)
This thesis deals with the characterisation of a specific compression process by monitoring the viscoelastic properties of pressed material. The theoretical part of the thesis describes the substances - microcrystalline cellulose and magnesium stearate. It also describes methods for the assessment of tablet viscoelasticity using the force-displacement diagram and factors influencing the viscoelasticity of tablets. The aim of the experimental part of the work is to characterise the viscoelastic properties of microcrystalline cellulose as well as a mixture of microcrystalline cellulose and magnesium stearate lubricant of various lubricant concentrations using the force-displacement diagram and calculation of tablet relaxation. Tablets were pressed from a mixture of aggregates of microcrystalline cellulose and magnesium stearate lubricant using a T1-FRO 50 machine at 11 molding pressures in the range of 1,9 -113,0 MPa with lubricant concentration in the range of 0 % - 2,50 %. The height and diameter of each tablet were measured immediately after pressing and the measurements were repeated 24 hours later. Measurements determined viscoelastic parameters E1, E2, E3, Elis, and P1, and the volumes of the tablets, both at time 0 and after 24 hours. The result of the study was to determine the effect of...
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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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Evaluation of compressibility of paracetamol
Šorf, Aleš ; Řehula, Milan (advisor) ; Ondrejček, Pavel (referee)
The objective of this work was to evaluate the compressibility of paracetamol by determination of compression and viscoelastic properties of the active substance and also to detect eventual changes in crystal modification of the substance during the compression process. The parameters of the compression equation were determined using tree-exponential equation developed at the Department of pharmaceutical technology. Mutual interactions between particles were also studied by stress relaxation test using compression forces 5, 10 and 15 kN, as well as energetic parameters of a force-distance record using compression forces from 5 to 40 kN. Tablets made in the last mentioned test were used as samples for DSC analysis to seek potential changes in the crystal structure of paracetamol when undergoing the compression process. The evaluation of the executed tests suggested that compression ability of paracetamol in basic form I is very poor and its plasticity when being compressed by commonly used pressures is about 50%, which is considered as very low. It was also found out that any crystal structure changes of the active substance did not occur during compression.
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