National Repository of Grey Literature 111 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Deformation index for tablets of microcrystalline cellulose
Myslivečková, Jana ; Řehula, Milan (advisor) ; Musilová, Marie (referee)
Myslivečková Jana - Rigorózní práce - 2006 This work deals with deformation index of tablets of microcrystalline cellulose. Theoretical part describes the theory of tablet formation by means of the record force - displacement. It also characterizes microcrystalline celluloses. The aim of the work was to find out the influence of a filler on the parameter E2 of the compression process and on the parameter DE of the destruction process. Further to asses the influence of the relation between parameters DE, D and E2,DE and effect of the filler type on new parameter DI. Six various fillers were tested. Ceolus KG 802 Avicel PH 102, Avicel PH 200, Pearlitol 100 SD, Tablettose 70, and Emcompress. The results show that polymeric microcrystalline celluloses accumulate less energy at compression than crystalline compounds. However, they have higher value of D. Microcrystalline celluloses have the highest values of the parameter DI. A semilogarithmic dependence was found between the parameters D and DE.
Determining the compression behaviour of celluloses.
Ondrejček, Pavel ; Řehula, Milan (advisor) ; Špaček, Vladimír (referee)
Mechanical resistance of tablets is usually described by crushing force, or by tensile strength. Method used in this thesis records crushing force and path of crushing. This force-path record can be used to calculate crushing energy. Crushing force, crushing path and crushing energy can be used to calculate other parameters that characterize tablet properties. This thesis uses crushing force, volume crushing force, tensile strength, crushing energy, volume crushing energy and crushing energy related to tablet weight to describe tablets compressed of powdered cellulose, microcrystalline cellulose, hydroxypropylcellulose and lactose monohydrate. Results of this thesis shows descent of tensile strength in this order: microcrystalline cellulose Avicel PH-112, microcrystalline cellulose Avicel PH-101, hydroxypropylcellulose, powdered cellulose and lactose monohydrate. Kinetic characteristics of tablets descent in this order: hydroxypropylcellulose, microcrystalline cellulose Avicel PH-101, microcrystalline cellulose Avicel PH-112, powdered cellulose and lactose monohydrate.
The use of DSC for assessment of content uniformity of metronidazol in suppositories
Maršálková, Lucie ; Musilová, Marie (advisor) ; Řehula, Milan (referee)
The aim of this work is the evaluation of extemporaneously prepared metronidazole-containing suppositories. Content uniformity, dispersion of the active ingredient, and the content in relation to the declared one was examined. The content of the active ingredient was determined by means of DSC. The preparations complied with the test of content uniformity. The content of the active ingredient was lower that the declared one.
Determination of the plasticity of lactose
Juhaňáková, Jana ; Řehula, Milan (advisor) ; Musilová, Marie (referee)
Juhaňáková Jana - Rigorózní práce - 2006 This work deals with the determination of tablet plasticity made of Tablettose 70 using stress relaxation method. Theoretical part of the work describes preparation and characterization of the tablets. It deals in detail with the determination of residual plasticity of Tablettose 70, determination of the influence of the dwell time on residual plasticity and on the dependence of residual plasticity on compression force. Plasticity was measured by means of T1 - -FRO 50 device. From the results of the work it follows that the increase in dwell time results in residual plasticity of Tablettose 70. Tablettose 70 has the parameter A 49.679 % and tangent B -13.712% kN-1 .
Determining the compression behaviour of microcrystalline cellulose and stearic acid
Šůrová, Eva ; Řehula, Milan (advisor) ; Adámek, Roman (referee)
This thesis is focused on characterization of a process of compression through finding viscoelastic properities of a pressed material. The theoretical part describes applicated substances, i.e. microcrystalic cellulose and stearic acid. Also elastic recovery measurement methods as well as factors which influence elastic recovery are described. The aim of the thesis was to determine viscoelastic properities of microcrystalic cellulose and mixture of microcrystalic cellulose and lubricant, acid stearic in diverse concentrations. To learn this, a force-displacement diagram and a calculation of a tablet relaxation was used. A machine T1 - FRO 50 pressed tablets by eleven various pressures within the range from 1,9 to 113,0 MPa. The tables were composed by a mixture of microcrystalic cellulose and lubricant acid stearic in a diverse concentration of lubricant within the range from 0% to 2,5%. After the tablets had been compressed, their high and their diameter were measured and 24 hours later this process of measurement was repeated. From this measurement we gaind viscoelastic parameters E1, E2, E3, Elis, Pl and tablet volumes in various time period (from 0 to 24 hours). In the research we found the influence of a pressed pressure and a concentration of lubricant upon the energy of compression and upon...
Effect of paracetamol on the parameters of compression equation
Mařanová, Lucie ; Řehula, Milan (advisor) ; Ondrejček, Pavel (referee)
Evaluation of the tableting mixtures containing the paracetamolum by the parameters of the equation of compression The diploma thesis deals with effect of paracetamol on the parameters of compression equation. These parameters characterize compression process in the individual phases of compression: precompression phase, phase of elastic deformation and phase of plastic deformation. Paracetamolum was studied in the five mixtures, where it occurred in different ratio with microcrystalline cellulose. Looseness, Carr's index and Hausner ratio were evaluated for each mixture. The sizes of reductions ai, sizes of energies Ei and Ri, "half-pressures" pHi and the velocity constants 1/ti were calculated using three-exponential equation of compression for the individual phases of pressing. The results showed poor flow properties of tableting mixtures and thus its unsuitability for direct compression. The results of the study have revealed that increasing amounts of paracetamolum in the mixture increase reduction of volume a1 and velocity of volume change 1/t1 in dependence on the amount of the extruded air and decrease the required energy due to the smooth surface and less friction during the precompression phase. Reduction of volume a2 decrease with the increase of content of paracetamol due to...
Determining the plasticity of calcium hydrogen phosphate
Hořínková, Pavla ; Řehula, Milan (advisor) ; Špaček, Vladimír (referee)
The essential condition for a compaction of materials are their viscoelastic properties. There are many methods how to determine them. During a compaction process we can obtain elastic and plastic energies or energy of particle friction from a force-displacement record. After compaction the Young's modul of elasticity can be calculated from the tablet dilatation's values. The stress relaxation test is used for working out the plasticity of a compacted material. Using this test we get values of the methods FminA, FminB, Fpl and parameters of first order equation describing the pressure decrease during the stress relaxation. The viscoelastic properties of calcium hydrogenphosphate dihydrate were evaluated in this work by above mentioned methods except for energies. The results obtained by these methods were 288,080 MPa for the Young's modul of elasticity and 700,5167 MPa.s for the total plasticity Pc. The greater this value is, the better compaction properties the material has.
Plasticity in Tablets from Microcrystalline Cellulose
Reich, Filip ; Řehula, Milan (advisor) ; Musilová, Marie (referee)
A study of parameters (power, speed), affect on force - displacement profile, microcrystalline celulose (AVICEL PH - 102® ) and other types of excipients in direct compression 2007, s. 1 - 73 Filip Reich Charles univerzity in Prague, Fakulty of Pharmacy, Institute of Pharmaceutical technology, Heyrovského street 1203, 500 05, Hradec Králové accepted 15th. may 2007 Abstract Compression behaviour, plasticity, of a direct compression excipient, microcrystalline celulose (AVICEL PH - 102), was studied in this work. The compaction property, plasticity, has been acquired with three methods,two procession with the "one-point" plotting, the last one with the "area" plotting. In this work avicel was tableting with slower and more even increase of the compacting power. Yielded results were compared with results from the studies of other laborers, who were solving the same problem by using different compaciton properties, including the speed of tableting 2 mm/s, and using also the same excipients. The acquired plasticity indicated, that these methods gave compareable results. In the force - plasticity profile we can find two apparent slots, the first characterize the phase before the start of compaction, the second one shows the phase of plastic deformation. The character of the force - plasticity curve in the phase...
Influence of compressing speed and time of constant load on the energy balance of tablets
Císařová, Daniela ; Řehula, Milan (advisor) ; Musilová, Marie (referee)
Císařová Dana - Rigorózní práce - 2006 This work deals with the influence of the compression rate and time of constant load on energy balance of tablets. Theoretical part characterizes microcrystalline celluloses, describes theory of tableting and theory of the force - displacement record. The aim of the work was to find out the influence cycle rate on the force Fmax , influence of the cycle rate and dwell time on parameters of energy balance, influence of the cycle rate on mechanical resistance of tablets. The determination was carried out with tablets of microcrystalline cellulose Avicel PH 200 using T1 - FRO 50 device. It follows from the results that the higher the cycles rate the higher values of parameters Emax and E1-3. Dwell time does not influence above-mentioned parameters. Radial strength des not change with the increase of cycle rate from 0.1 to 2 mm/s. Further increase in cycle rate brings about higher strength of tablets. Optimal cycle rate is 1 mm/s.
Calculation of elasticity and plasticity of microcrystalline cellulose Ceolus KG 802
Filipčíková, Michaela ; Řehula, Milan (advisor) ; Musilová, Marie (referee)
Calculation of Elasticity and Plasticity of Microcrystalline Cellulose Ceolus KG 802 Mgr. Michaela Filipčíková, 2007 Microcrystalline cellulose is an important pharmaceutical excipient. Ceolus KG 802 is one type of microcrystalline cellulose, which reduces addition amount of pharmaceutical powders. It also facilitates tableting of pressure - sensitive drugs such as enzymes, antibiotics etc. The aim of this Rigorous thesis was the calculation of elasticity and plasticity of microcrystalline cellulose Ceolus KG 802. The plasticity was determined from graphs showing the decreasing trend of force on the time. We used three methods. First one was based on identification of maximum and minimum forces, second used "one-parameter" evaluation of curve from graphs showing the relation of the force to the time and third "three-parameter" evaluation of these curves. We also determined Young's modulus which characterizes elasticity of system and equals 100,0287 MPa. We were able to distinguish two sections of the curve from graphs showing the relation of the plasticity to the compression force. These sections characterize particular phases of compression and changes of system. We distinguished phase of precompression, then phase of elastic and plastic deformation. This rigorous thesis deals with confrontation...

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