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Surface active compounds and evaluation of its properties
Lanzendorfová, Jana ; Holas, Ondřej (advisor) ; Paraskevopoulos, Georgios (referee)
Charles University, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Mentor: PharmDr. Ondřej Holas, PhD. Consultant: PharmDr. Jan Marek, PhD. Student: Jana Heinrichová Title of Thesis: Surface active compounds and evaluation of its properties The theoretical part of the thesis is focused on the properties of surfactants, their distribution, and their use. In this part, micelles, critical micelle concentration, methods of its determination and factors influencing it are also characterized. In the experimental part, the critical micelle concentration (CMC) of two homologous series of quaternary ammonium salts (benzalkonium chlorides and benzoxonium chlorides) was evaluated by a conductometric method. Several parameters (side chain length, temperature, pH) and their influence on the critical micelle concentration value were monitored. Furthermore, the critical micelle concentration of these substances was measured using a Wilhelmy plate to compare the two methods. The relationship between decreasing critical micelle concentration value and increasing alkyl chain length was verified. At the same time, the dependence of CMC on temperature and pH change was verified. Finally, the conductometric method of CMC determination was compared with the Wilhelmy plate method, and their...
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The evaluation of the effect of PAMAM dendrimers in the solubility of lmiquimod
Micková, Thu Thao ; Paraskevopoulos, Georgios (advisor) ; Paraskevopoulou, Anna (referee)
Charles University, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Supervisor: Dr. Georgios Paraskevopoulos, Ph.D. Consultant: Eleni Panoutsopoulou Author: Mgr. Thu Thao Truongová Title of the thesis: The evaluation of the effect of PAMAM dendrimers in the solubility of Imiquimod Dendrimers are highly branched polymeric compounds with defined properties. They are used as a nanoparticle delivery system, however concurrently they have significant potential in enhancing the solubility of poorly water soluble drugs. Dendrimers work as drug carriers either by encapsulating the drug in their branched internal structure or they create interactions with the drug in the outer layer via terminal functional groups. The aim of this work was to evaluate the effect of polyamidoamine (PAMAM) dendrimers on the solubility of the hydrophobic drug imiquimod. Solutions of zero, first, second and third generation dendrimers were prepared at six different concentrations. During the experiment, the pH of the solutions was measured before and after addition of excess amount of imiquimod. Subsequently, analysis was performed by high-performance liquid chromatography. The measured results show that the first generation of PAMAM dendrimers is able to increase the solubility of imiquimod in...
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2-hydroxyethyl cellulose gels with novel polyamidoamine dendrimers for the skin application of Imiquimod
Prokopová, Michaela ; Paraskevopoulos, Georgios (advisor) ; Kováčik, Andrej (referee)
Charles University, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Supervisor: Dr. Georgios Paraskevopoulos, Ph.D. Author: Michaela Prokopová Title of the thesis: 2-hydroxyethyl cellulose gels with novel polyamidoamine dendrimers for the skin application of Imiquimod Imiquimod (IMQ) is a medicinal substance used in the therapy of skin diseases (carcinomas). IMQ's hydrophobicity does not allow its incorporation in hydrophilic gels, which are the most used gel formulations for topical application. Dendritic molecules, which are highly branched polymers, could potentially increase the solubility of IMQ in hydrophilic formulations for the preparation of more concentrated hydrophilic dosage forms. The purpose of this work was to increase the concentration of IMQ in hydrophilic formulations using dendritic molecules. First, aqueous solutions containing IMQ were prepared, in the presence or absence of different generations and concentrations of dendritic molecules. The pH of the solutions was adjusted to 5,5, which corresponds to the pH of the skin. After that, 2-hydroxyethyl cellulose was used as gelling agent to prepare hydrophilic gels as preferable formulations for topical application. Selected solutions and gel formulations, were used for permeation experiments on human...
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2-hydroxyethyl cellulose gels with novel polyamidoamine dendrimers for the skin application of Imiquimod
Prokopová, Michaela ; Paraskevopoulos, Georgios (advisor) ; Kováčik, Andrej (referee)
Charles University, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Supervisor: Dr. Georgios Paraskevopoulos, Ph.D. Author: Michaela Prokopová Title of the thesis: 2-hydroxyethyl cellulose gels with novel polyamidoamine dendrimers for the skin application of Imiquimod Imiquimod (IMQ) is a medicinal substance used in the therapy of skin diseases (carcinomas). IMQ's hydrophobicity does not allow its incorporation in hydrophilic gels, which are the most used gel formulations for topical application. Dendritic molecules, which are highly branched polymers, could potentially increase the solubility of IMQ in hydrophilic formulations for the preparation of more concentrated hydrophilic dosage forms. The purpose of this work was to increase the concentration of IMQ in hydrophilic formulations using dendritic molecules. First, aqueous solutions containing IMQ were prepared, in the presence or absence of different generations and concentrations of dendritic molecules. The pH of the solutions was adjusted to 5,5, which corresponds to the pH of the skin. After that, 2-hydroxyethyl cellulose was used as gelling agent to prepare hydrophilic gels as preferable formulations for topical application. Selected solutions and gel formulations, were used for permeation experiments on human...
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Surface active compounds and evaluation of its properties
Heinrichová, Jana ; Holas, Ondřej (advisor) ; Paraskevopoulos, Georgios (referee)
Charles University, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Mentor: PharmDr. Ondřej Holas, PhD. Consultant: PharmDr. Jan Marek, PhD. Student: Jana Heinrichová Title of Thesis: Surface active compounds and evaluation of its properties The theoretical part of the thesis is focused on the properties of surfactants, their distribution, and their use. In this part, micelles, critical micelle concentration, methods of its determination and factors influencing it are also characterized. In the experimental part, the critical micelle concentration (CMC) of two homologous series of quaternary ammonium salts (benzalkonium chlorides and benzoxonium chlorides) was evaluated by a conductometric method. Several parameters (side chain length, temperature, pH) and their influence on the critical micelle concentration value were monitored. Furthermore, the critical micelle concentration of these substances was measured using a Wilhelmy plate to compare the two methods. The relationship between decreasing critical micelle concentration value and increasing alkyl chain length was verified. At the same time, the dependence of CMC on temperature and pH change was verified. Finally, the conductometric method of CMC determination was compared with the Wilhelmy plate method, and their...
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Formulation, characterization and skin application of Imiquimod loaded liposomes in combination with dendrimers
Trecáková, Viktória ; Paraskevopoulos, Georgios (advisor) ; Holas, Ondřej (referee)
Charles University, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Supervisor: Dr. Georgios Paraskevopoulos, Ph.D. Consultant: Eleni Panoutsopoulou Author: Viktória Trecáková Title of thesis: Formulation, characterization, and skin application of Imiquimod loaded liposomes in combination with dendrimers The skin barrier formed in the uppermost skin layer by the stratum corneum - among many functions - restricts the penetration of drugs through the epidermis. Nanoparticles such as liposomes and dendrimers, used for (trans) dermal drug delivery, offer a solution how to overcome this limitation. Conventional liposomes with an encapsulated drug have proven increased effectiveness and prolonged drug release for local drug delivery across intact skin in comparison to free drug. In order to increase the effectiveness of liposomes, their combination with different delivery systems has been suggested. In this study, Imiquimod was loaded to liposomes in the presence of different generations of in-house synthesized dendrimers forming novel advanced drug delivery nanosystems (aDDnSs). After an ex vivo permeation experiment on human skin, the lower generation of dendrimers was found to act synergistic with liposomes and delivered more active substance to the epidermis, while...
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Formulation, characterization and skin application of Imiquimod loaded liposomes in combination with dendrimers
Trecáková, Viktória ; Paraskevopoulos, Georgios (advisor) ; Holas, Ondřej (referee)
Charles University, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Supervisor: Dr. Georgios Paraskevopoulos, Ph.D. Consultant: Eleni Panoutsopoulou Author: Viktória Trecáková Title of thesis: Formulation, characterization, and skin application of Imiquimod loaded liposomes in combination with dendrimers The skin barrier formed in the uppermost skin layer by the stratum corneum - among many functions - restricts the penetration of drugs through the epidermis. Nanoparticles such as liposomes and dendrimers, used for (trans) dermal drug delivery, offer a solution how to overcome this limitation. Conventional liposomes with an encapsulated drug have proven increased effectiveness and prolonged drug release for local drug delivery across intact skin in comparison to free drug. In order to increase the effectiveness of liposomes, their combination with different delivery systems has been suggested. In this study, Imiquimod was loaded to liposomes in the presence of different generations of in-house synthesized dendrimers forming novel advanced drug delivery nanosystems (aDDnSs). After an ex vivo permeation experiment on human skin, the lower generation of dendrimers was found to act synergistic with liposomes and delivered more active substance to the epidermis, while...
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Active encapsulation of imiquimod in liposomes with dendrimers
Manna, Dina Faeq Mohd Said ; Paraskevopoulos, Georgios (advisor) ; Paraskevopoulou, Anna (referee)
Charles University, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Supervisor: Dr. Georgios Paraskevopoulos, Ph.D. Consultant: Eleni Panoutsopoulou Author: Dina Manna Title of the thesis: Active Encapsulation of Imiquimod in Liposomes with Dendrimers One of the main obstacles to tackle when dealing with drug delivery systems such as liposomes is efficiently loading adequate concentration of active ingredient. Drug encapsulation in liposomes occurs in two possible methods: passive and active loading. Passive drug loading involves the capture of drugs into the liposome whilst it is being prepared. Active loading however is the passage of drug through liposome's phospholipid bilayer after the liposome is fully formed. This method has been shown to be effective for low molecular weight ionizable active components and it was hypothesized to be an effective method of encapsulation of imiquimod. IMQ is an imidazole quinolone drug known for its extreme hydrophobicity and basicity and have been used for skin diseases (e.g. skin cancer). During our approach, liposomes were prepared using the classical thin layer method while the lipids were hydrated with aqueous solution of in-house synthesized first-generation dendrimer of two different concentrations (5 mM and 10 mM). Once...
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Rheological properties of silicone gels for scar treatment
Khorsand, Ghazal ; Šnejdrová, Eva (advisor) ; Paraskevopoulos, Georgios (referee)
Charles University, Faculty of Pharmacy in Hradci Králové Department of Pharmaceutical Technology Supervisor: PharmDr. Eva Šnejdrová, Ph.D. Student: Ghazal Khorsand Title thesis: Rheological properties of silicone gels for scar treatment The thesis is focused on testing of the flow and viscoelastic properties of the scar treatment silicone-based gels, either commercially available or newly formulated gels under development. The theoretical part deals with the scar formation, silicone in scar treatment, and characterization of the gels. In the experimental part, rotational and oscillation tests were performed using a rotational rheometer. The obtained flow curves were fitted by Newton or Power law models. The shear viscosity, coefficient of consistency, and index of flow behaviour were used for gel characterization and comparison. The highest viscosity revealed in the ScarEsthetique cream, followed by RejuvaSil gel. Surprisingly, the Stratamed scar gel and Scar gel Dr. Max showed the lowest viscosity, even lower than the formulations at the development stage. Despite the name "gel", they behave as Newtonian fluids. The elastic modulus G', viscous modulus G'', and complex modulus G*, phase angle , the gel point, and linear viscoelastic region LVER were selected to describe the viscoelastic behaviour...
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Effect of the generation of amino-decorated polyamidoamine dendrimers with ethylenediamine core at the (trans)dermal delivery of 5-fluorouracil
Houšková, Denisa ; Paraskevopoulos, Georgios (advisor) ; Holas, Ondřej (referee)
Charles University, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Supervisor: Dr. Georgios Paraskevopoulos, Ph.D. Consultant: Mgr. Anna Nová ková Author: Denisa Houšková Title of thesis: Effect of the generation of amino-decorated polyamidoamine dendrimers with ethylenediamine core at the (trans)dermal delivery of 5-fluorouracil. Dendrimers can be defined like highly branched, star-shaped macromolecules with nanometer-scale dimensions and unlimited applications in both biological and materials sciences. Polyamidoamine (PAMAM) dendrimers have been used to effectively enhance the (trans)dermal drug delivery of several active substances. Inspired by the structure of PAMAM dendrimers, a new class of dendrimers was designed having amino-functionalized periphery and ethylenediamine core. A repeating motif of bis(2-aminoethyl)glycine was used for generation growth up to the third generation. The new dendritic molecules of zero, first, second and third generation were tested for their ability to enhance the deposition of 5-fluorouracil in the different layers of human skin ex vivo by using Franz diffusion cells. The results suggest that the new dendrimers, at a concentration of 20 mg/mL in 60 % propylene glycol in water as vehicle, are able to deliver 5-fluorouracil at the...
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