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The contribution to the study of the swelling mechanism of aliphatic oligoesters
Faukner, Antonín ; Dittrich, Milan (advisor) ; Šnejdrová, Eva (referee)
This work deals with interaction of oligoester carriers based on DL-lactic-co-glycolic acid, with hydrophilic medium. The interaction results with phenomena of degradation, erosion and swelling of delivery system. The purpose of this work was to quantify water soluble, high osmotically active degradation products generated via hydrolysis in the matrices, and to find a connection between concentration of degradation products and changes of swelling in time. Experiments with two types of branched polymers were realized. The main difference between the both had origin in the concentration of tripenterythritol used as branching monomer and in the blending of this polymer with 20% triethylcitrate used as plasticizer. Matrices differ in size too. The method used included parallel gravimetric monitoring of erosion and swelling of matrices and alkalimetric quantifying of degradation acid hydrolysis products. The last mentioned parameter was obtained by the separation of hydrophilic and lipophilic fractions of matrices between organic and aqueous phase. Narrow correlation between matrices swelling rate and simultaneously proven concentration of hydrophilic oligoesters generated in matrices was established.
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The preparation of biocompatible silver nanodispersions by the reduction of their solutions
Ulahelová, Jana ; Dittrich, Milan (advisor) ; Kvítek, Libor (referee)
The aim of the thesis was focused into the range of factors influencing the size of silver nanoparticles usable as antimicrobials prepared by Tollens method. This method is based on reduction reaction of silver salts or silver complexes with reduction agents. Mono-, oligo-, and polysacharides are regarded as the most useful compounds for this purpose with regard to their minimal toxicity and high biocompatibility. It was concluded that various hydrodynamic conditions realized via usual stirring by laboratory stirrer, or microwaves source action, or in relatively static conditions, don't influence the condensation process in the different extent. Temperature rising to 85 řC didn't influence the size of nanoparticles also. Polymers and oligomers, as polyvinylalcohol, starches, and polydextroses has been found as the very appropriate reduction agents. The prepared samples consisted of very fine nanoparticles, the size characteristics represented by intensity and volume diameters were in the order of units of nanometers, the polydispersity indexes were of very low values.
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Carboxyl number as the degradation parameter of polyesters
Ťápalová, Lenka ; Dittrich, Milan (advisor) ; Šnejdrová, Eva (referee)
The rigorous work connects on the thesis from years 2007-2008. It deals with interaction of hydrophilic medium with three aliphatic oligoesters and polyesters synthesized at the pharmaceutical faculty from lactic acid and glycolic acid, which were branched either with dipentaerythritol in 2 % concentration or with tripentaerythritol in 3 % or 5 % concentrations. Samples with three various weights were prepared from polyesters branched with 3 % tripentaerythritol (150 mg, 500 mg, 1250 mg). The polyesters in the weight of 1250 mg was plasticized with triethylcitrate. There was observed a process of erosion kinetics and swelling of defined matrices from above mentioned oligoesters in aqueous medium at 37 řC in period of time 1 day, 3 days, 7 days, 14 days, 21 days and someone of them 28 days again. There was determined the concentration of carboxylic groups generated by hydrolysis of matrices in the water soluble fraction (carboxylic number) using alkalimetric method. The novel aspect of this work consists in the study of the matrices size and its plasticization on these characteristics. The time of erosion process beginning and the time of swelling degree peak achievement delays with the increasing of size of matrices. The time of peak of carboxylic number values as well as hysteresis manifests more...
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The adhesive properties of the oligoesters of lactic acid and glycolic acid branched with dipentaerythritol
Páblová, Sylva ; Šnejdrová, Eva (advisor) ; Dittrich, Milan (referee)
The theoretical part of this rigorous theses describes concept of bioadhesion in the drug administration and characterizes some of basal ways of the drug administration (oral, peroral, ophthalmic, nasal, vaginal). It also specifies the bioadhesive dosage forms in use. The aim of the experiment was to study the adhesiveness of with dipentaerythritol branched D,L-lactic and glycolic acid oligoesters using Material testing machine Zwick/Roell T1- FR050TH.A1K. The maximum force (Fmax) required to detaching the polymer systems from substrate was measured for determination of the adhesiveness of the oligoesters. Rheological properties were measured using Brookfield digital viscosimeter DV-E. It was found that Fmax of the branched oligoesters decreases with growing molecular weight and branch level. Adhesiveness of samples on the non-stick base: PLGA, 0,5D and 1D were approximately the same, 2D was of lower value. The numbers of on the pig ear base measurement were multiple lower. There was a decrease of viscosity of the adhesive polymers in the order: PLGA, 0,5D, 1D, 2D.
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The adhesive properties of the oligoesters branched with pentaerythritol and tripentaerythritol
Podzimková, Šárka ; Šnejdrová, Eva (advisor) ; Dittrich, Milan (referee)
Theoretic part deals with bioadhesion of peroral substances (concretely peptides and proteins), its limitations and improvement feasibilities. Next chapter describes today most used bioadhesives. Cytoadhesion is analysed in more detail; theoretic part is concluded with characterisation of endocytosis and transcytosis. Experimental part of thesis investigates rheologic and adhesive properties of plasticized oligoesters of D,L-lactic acid and glycolic acid in ratio 1:1 branched with pentaerythritol or tripentaerythritol. Adhesivity was measured on the Material testing machine T1- FR050TH.A1K Zwick/Roell as maximal force Fmax required to detache the polymer system from susbstrate. These values were converted to the size of the contact area and compared with values gained in diploma thesis. Viscosity of samples was measured using viscosimeter Brookfield DV-E with an adaptor for small sample amount by 37řC temperature with spindle 14. Measured values from both of the experiments were compared with values of plasticized linear oligoester formed by equimolar amount of L-lactic acid and glycolic acid measured during equal conditions. From the outcomes of made experiments ensues that samples branched with tripentaerythritol have higher adhesive force than carriers branched with pentaerythritol, adhesive...
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Image analysis of microparticles prepared by spray drying method
Sedláček, Petr ; Dittrich, Milan (advisor) ; Šnejdrová, Eva (referee)
ABSTRACT-EN In the thesis was demonstrated manitol as the proper model substance for optimization procedure of spray drying in Büchi Mini Spray Dryer B-290. Concentration of model polyol was in the range from 5 % to 15 %, the proper temperature in inlet part of device was 110 řC- 120 řC. The powder with low residual moisture was obtained, diameter of particles was around 5 micrometers. Effective were small concentrations of polydextrose and lecitine as additives in manitol.
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Oligoester matrices with antimicrobial drugs III.
Lazařová, Klára ; Šnejdrová, Eva (advisor) ; Dittrich, Milan (referee)
Klára Lazařová Diploma thesis 2008 The aim of this work was the study of the fluconazol and terbinafine release from oligoester carriers branched with various concentration of either mannitol (3M, 5M, 8M) or dipentaerythritol (3D, 5D, 8D) and plasticized with 30 % triethyl citrate (TEC). Theoretical part is occupied with drug delivery systems and the conditions of the coupling of the macromolecules with the biological substrates. The 150,0 mg matrices composed of carrier, drug of 4% and plasticizer TEC of 30% were prepared. They were put to the static dissolution test using phosphate citrate buffer pH 5,0 at 37řC. The drug release was determined spectrophotometricaly at 261 nm for Fluconazole and 283 nm for Terbinafine. Fluconazole release was the fastest from carrier 5D. The carriers 5D and 8D released the drug during three stages, after burst effect was observed constant liberation followed slowing the process. The carriers branched using mannitol released the drug depending of the concentration of the mannitol.
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Oligoester matrices with antimicrobial drugs II.
Kapiasová, Jana ; Šnejdrová, Eva (advisor) ; Dittrich, Milan (referee)
Jana Kapiasová Diploma Thesis 2006 The objective of this graduation thesis was a description of a liberation of acyclovir and terbinafine from plasticized oligoesters drug carriers. The terpolymers of D,L-lactic acid, glycolic acid and dipentaerythritol or mannitol [LA/GA/D(M)] were used as carriers of the drugs. Theoretic part is devoting to characteristics of the polyesters, mechanism of the hydrolytic degradation and importance of the citrate plasticizers. At the experimental section we used dissolution tests in order to obtain a concentration of released model drugs by spectrophotometer. Process of liberation was diagrammatized like a dependence of cumulative percentage of released drug at a time. The results indicate that fluconazol was released from carriers 3M and 8D fluconazol very fast, during 24 hours. On the other hand realising or the fluconazol from carriers 5M and 3D was very slow for the 8 days. Despite of the complete degradation the matrices during the dissolution test, there was no terbinafine determined in the dissolution liquid. It will be necessary to use different analytical method.
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Biodegradable nanoparticles formulation
Čermáková, Věra ; Dittrich, Milan (advisor) ; Šnejdrová, Eva (referee)
ABSTRAKT-EN Nanoparticles from poly(DL-lactic acid) were prepared by the using of disintegrator stator and rotor type. The intensity average diameter of these particles was 220 nanometers. Classical w/o emulsion-solvent distribution method was adopted for this purpose. Dichloromethane was used as more appropriate as chloroform. As emulsifying agent was tested polyvinylalcohol, better results were obtained with low-molecular weight compound, with Mw approx. 10,000.
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Thermal analysis of branched oligoesters
Volprechtová, Leona ; Dittrich, Milan (advisor) ; Šnejdrová, Eva (referee)
ABSTRAKT- EN Thermal characteristics of oligoesters with linear and branched constitution of molecule were studied.It was revealed the decreasing tendency of the both characteristics - specific heat of glass transition temperature and glass transition temperature values. The reason of this fact was in deterioration process of polyester molecule by hydrolysis. In the buffer solutions surroundings with pH above 7 end groups are ionized with consequences in increasing glass transition temperatures of oligoesters.
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