Download or read book Investigation of Microemulsions and Their Microstructures for Transdermal and Dermal Drug Delivery written by Ji Zhang and published by . This book was released on 2017 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: Drug delivery through the skin, transdermally and topically, offers many advantages including reduced systemic toxicity and side-effects, avoidance of the hepatic first pass metabolism, improved patient compliance, enabling sustained or controlled drug release, and enhanced delivery to local target tissues. However, there are many challenges for this route of administration, the major one is the skin barrier function to drug permeation. Many different approaches have been studied and used for enhancing the drug skin permeation. Among them, chemical permeation enhancers and microemulsion formulations are some of widely studied approaches. The thesis work focused on microemulsion (ME) formulations for enhancing transdermal or dermal drug delivery. Specifically, the ME microstructures were investigated and correlated with enhancement effects of drug skin permeation or skin deposition. The results showed that a critical factor influencing ME formulation behavior was the water content that also correlated to the formulation microstructure, and the drug skin permeation increased significantly corresponding to the microstructure change from W/O, to Bi-continuous, and to O/W. This was the first time that this phenomenon had been systematically studied and reported, the microstructure of a microemulsion affected both hydrophobic and hydrophilic model drugs' transdermal permeation. The extent of trandermal permeation enhancement effect was more significant for hydrophobic drugs than hydrophilic drugs as water content increased and the corresponding microstructure changed in the ME formulation. Furthermore, at fixed water content, increasing oil content would result in higher transdermal permeation enhancement. The model drugs used in the study were lidocaine, ketoprofen, and caffeine, which represented compounds of varied physical and chemical properties. The findings were of practical significance for microemulsion formulation design and development in transdermal drug delivery. Secondly, in the present study, a combination of analytical methodologies was utilized to examine microemulsion microstructures. It was found that the cooling thermogram generated by Differential Scanning Calorimetry (DSC) provided a simple approach for microstructure determination, which to the author's knowledge, had not been reported before. Extensive DSC cooling experiments had been conducted to analyze three ME systems that had their microstructure characterized and known in the literature. It was showed that DSC derived microstructure results were in complete concordance with literature reports, and thus demonstrated that the cooling DSC method was an effective analytical technique for ME microstructure assessment. The results also showed that the DSC method provided additional advantages over conventional methods for being sensitive, accurate, and versatile. The developed cooling DSC methodology for ME microstructure analysis would greatly facilitate ME formulation characterization and development in the future. Finally, dermal delivery of hydrophobic drugs by microemulsion (ME) formulations and effect from ME microstructures were studied. The antifungal drug, clotrimazole (CLOT), was used as the model compound. ME formulations of different microstructures were prepared along water dilution line at fixed oil/(surfactant and co-surfactant) ratio of 1/9 (w/w) using isopropyl myristate as oil, Labrasol and Cremophor EL as surfactant and co-surfactant, and water. Permeation experiments on human cadaver skin were conducted for ME and the control formulations of different CLOT loads. Dermal delivery of CLOT assessed by the dermal drug concentrations was found to be significantly higher for MEs when compared with the control formulation, and the highest concentration was observed with O/W ME, suggesting ME microstructure was an important formulation variable for enhancing dermal delivery. ME gel formulations prepared by incorporating 1.0% (w/w) of Carbopol 980 showed comparable dermal CLOT concentration to MEs but up to 2.4 fold higher than the commercial CLOT cream product, Lotrimin®. Furthermore, FITC used as a model compound for highly hydrophobic drugs, was also studied for its dermal delivery by MEs in porcine skin penetration experiments. Results showed a consistent ME microstructure effect, suggested by significantly higher FITC concentrations in all skin layers, stratum corneum, viable epidermis, and dermis, from O/W ME over Bi-continuous and W/O MEs. Results from the present study highlighted ME microstructure effect on ME dermal delivery of hydrophobic drugs, and provided insight to drug dermal retention and transdermal permeation enhancements and their interplay.
Download or read book Investigations of Pharmaceutical Oil in water o w Microemulsions as Drug Delivery Systems written by Chien-Ming Hsieh and published by . This book was released on 2009 with total page 554 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present study characterizes the physico-chemical and drug solubilisation properties of a range of oil-in-water (o/w) microemusions prepared using one of a number of C12 hydrophobic chain surfactants namely: (i) the zwitterionic surfactant dodecyldimethylammoniumpropylsulphate (DDAPS), (ii) the cationic surfactant dodecyltrimethylammonium bromide (DTAB) and (iii) the anionic surfactant sodium dodecylsulphate (SDS) and containing as oil, either of the ethyl esters, ethyl butyrate (EB) or ethyl caprylate (EC). -- A combination of physico-chemical techniques, including phase behaviour studies, drug solubilisation studies, surface tension measurements, viscometry, light scattering (dynamic and static) and small angle neutron scattering (SANS) in combination with contrast variation have been used to determine the detailed molecular architecture of the microemulsions formed by DDAPS. The microemulsions prepared using either DT AB or SDS were studied using in less detail using only phase behaviour and drug solubilisation studies and SANS in conjunction with contrast variation to determine their microstructure. For all surfactants studied, the effect of the solubilisation of the poorly-water drug, testosterone propionate, on the detailed structure of the microemulsions was examined using SANS in combination with contrast variation. -- The microemulsions formed by DDAPS were found from light scattering and viscometric studies to be ellipsoidal in nature, although neither technique was sensitive enough to allow the exact dimensions of the aggregates to be determined. SANS studies showed that the micelles and microemulsions formed by each of the C12 surfactants were prolate elliposoids and that the presence of drug did not alter their shape.
Download or read book Topical and Transdermal Drug Delivery written by Heather A. E. Benson and published by John Wiley & Sons. This book was released on 2012-02-03 with total page 393 pages. Available in PDF, EPUB and Kindle. Book excerpt: Practical drug development approaches presented by leading experts Designed to support the development of new, effective therapeutics, Topical and Transdermal Drug Delivery: Principles and Practice explains the principles underlying the field and then demonstrates how these principles are put into practice in the design and development of new drug products. Drawing together and reviewing the latest research findings, the book focuses on practical, tested, and proven approaches that are backed by industry case studies and the authors' firsthand experience. Moreover, the book emphasizes the mechanistic information that is essential for successful drug product development. Topical and Transdermal Drug Delivery: Principles and Practice is divided into two parts: Part One, Current Science, Skin Permeation, and Enhancement Approaches, offers readers a fundamental understanding of the underlying science in the field. It describes the principles and techniques needed to successfully perform experimental approaches, covering such issues as skin permeation, enhancement, and assessment. Part Two, Topical and Transdermal Product Development, guides readers through the complete product development process from concept to approval, offering practical tips and cautions from experts in the field. This part also discusses regulations that are specific to the development of dermal drug products. The final chapter explores current and future trends, forecasting new development techniques and therapeutics. Throughout the book, the authors clearly set forth the basic science and experimental procedures, making it possible for researchers to design their own experimental approaches and accurately interpret their results. With contributions from experienced drug researchers, this text is highly recommended for all researchers involved in topical and transdermal product development who need to know both the state of the science and the standards of practice.
Download or read book Topical and Transdermal Drug Delivery Systems written by Nayan A. Gujarathi and published by CRC Press. This book was released on 2023-02-06 with total page 353 pages. Available in PDF, EPUB and Kindle. Book excerpt: Topical and transdermal drug delivery systems (TDDs) have several advantages over traditional drug delivery methods, as they can be less invasive, more sanitary, more cost-effective, and may result in better patient compliance. TDDs play a significant role in therapeutics with a variety of preparations and approaches designed by expert formulation scientists. This volume integrates a wide variety of case studies, research, and theories to reveal their diversity and capture the novel approaches of transdermal and topical drug delivery employed by developers and content experts in the field. It provides an abundance of important information and state-of-the-art research on topical and transdermal drug delivery systems and addresses the basics of drug delivery systems, strategies to enhance permeation across membranes, and formulation and evaluation of diverse dosage forms. The volume presents an evaluation of the pros and cons of conventional drug delivery systems against TDDs and discusses the nuances of micro- and nano-systems in TDDs. The extraordinary packages of nano systems (vesicular systems, polymeric nanoparticles, nanoemulsion and dendrimers) are broadly discussed, and their applications are reviewed through a transdermal route. The book looks at TDDs and the main nanoparticles used in skin diseases and lesions of the aging, such as psoriasis, vitiligo, cancer, lesions of the aging and others. Chapters also discuss polymeric micelles in topical and transdermal delivery; microneedles; emulsion, nanoemulsion and microemulsion; TDDs in pulmonary drug delivery systems; nanoencapsulated nasal drug delivery systems; skin sensitivity and irritation testing for transposing transdermal drug delivery systems; and regulatory aspects of drug development for dermal products. Topical and Transdermal Drug Delivery Systems: Applications and Prospects will be a valuable resource for pharmaceutical scientists and researchers, industry professionals, and academicians and students of the pharmaceutical and biomedical sciences.
Download or read book Design Optimization and Characterization of Ibuprofen Microemulsions and Microemulsion based Gels written by Sujata Pandey and published by . This book was released on 2020 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transdermal and topical drug delivery has been used as an alternative approach to oral drug delivery due to the various benefits it offers, including avoidance of the hepatic first pass metabolism, improved patient compliance, sustained or controlled drug release, and enhanced delivery to local target tissues. However, the barrier function of the skin, especially the stratum corneum, is a major challenge of drug permeation. Many different formulation techniques and approaches have been studied for enhancing drug permeation into the skin. The use of chemical permeation enhancers and formulations approaches, such as microemulsions, are some of the effective techniques to increase drug permeation. This thesis work focused on the composition and microstructures of microemulsions for enhancing the dermal delivery of ibuprofen. The effect of the type and composition of microemulsions, and the type of permeation enhancers incorporated into the microemulsions on the permeation and release profile of ibuprofen were studied. Four microemulsions were formulated, which were selected based on the pseudo-ternary phase diagrams. Among the four microemulsions, in two microemulsions (F2 and F4), 2% Carbopol 940 was incorporated as a gelling agent to form a gel base. Although the water content of F1 and F2 - both containing oleyl alcohol as the penetration enhancer - was low compared to formulations containing Transcutol® (i.e., F3 and F4), a higher permeation was observed for F1 and F2. The results suggest that water content played an important role in the better permeation of F1 and F2. Specifically, the findings suggest that the role of water content in the formulation could be more crucial than other parameters depending upon the permeation enhancer used in the formulation. It could be that the performance of the permeation enhancer, Transcutol®, depended more upon the water content of the formulation compared to formulations rich in fatty acid derivatives. However, a detailed study with varying concentrations of water in the formulations is required to validate the findings. Transcutol® is an effective permeation enhancer but the water content of the formulation containing Transcutol® needs to be optimal to increase drug permeation. These results suggest that based on the type of permeation enhancer used, the water content in the formulation must be considered differently and optimized accordingly. It further suggests that although Transcutol® is an effective permeation enhancer, the optimization of the formulation is an important parameter affecting its action in the formulation. The high permeation from formulations containing oleic acid and oleyl alcohol could be due to the amount of fatty acid derivatives in the formulation. Fatty acids, such as oleic acid, and fatty alcohols, such as oleyl alcohol can interact with the lipids in the stratum corneum (SC) leading to a synergistic increase in the SC's fluidity, which also increases drug mobility. When comparing the DSC profiles of F1 and F2, two exothermic peaks were observed in the cooling thermogram while no exothermic peaks were obtained in F3 and F4.
Download or read book Biocompatible Nonionic Microemulsions written by Ljiljana Djekic and published by LAP Lambert Academic Publishing. This book was released on 2012 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rigorous regulations in pharmaceutical industry urge for more sophisticated approaches that could be used for design and characterisation of drug delivery systems. Microemulsions are promissing carriers of active pharmaceutical ingredients. Researchers in this field are focused on development of biocompatible microemulsions stabilised by nonionic surfactants mixtures. The efficiency of tensides mixtures for microemulsion formation, their microstructure, solubilisation capacity, and mechanisms of drug release are scarcely investigated. This book provides a new formulation strategy of microemulsions based on multicomponent surfactant mixtures by conducting phase behaviour study and developing arteficial neural network models suitable for microemulsion area modeling. There is also demenstrated evaluation of colloidal microstructure, drug solubilisation capacity, and in vitro drug release mechanism of a model drug ibuprofen. The comprehensive approach for nonionic microemulsion carriers design may be useful to formulators in pharmaceutical, cosmetic and food industries as well as for anyone else who are interested in research and application of such complex systems.
Download or read book Microemulsions written by Taylor Torres and published by Nova Science Publishers. This book was released on 2016-12 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this book, Chapter One summarizes novel observations regarding physicochemical properties, physical and chemical stability, and drug delivery potential of microemulsion hydrogel drug delivery systems, based on comprehensive reviews of the research results from relevant scientific publications. Chapter Two discusses the synthesis and investigation of the properties of hexaferrites obtained by microemulsion techniques. Chapter Three focuses on manufacturing solid lipid nanoparticle dispersions using a microwave assisted microemulsion approach.
Download or read book In situ Phase Transition from Microemulsion to Liquid Crystal with the Potential for Prolonged Parenteral Drug Delivery written by Xiazhong Ren and published by . This book was released on 2012 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: Background and Aim: Parenteral microemulsions (MEs) have been employed as delivery vehicles to solubilise both hydrophilic and lipophilic drugs. The spreadability of the delivery vehicle determines the total surface area available for drug release in a biological system. A faster spreading vehicle gives a more rapid drug release profile compared to the slower spreading vehicle. Upon addition of aqueous medium, the occurrence of a possible phase transition from a ME to a liquid crystal (LC) or to a coarse emulsion (CE) leads to differences in their spreadability and drug release. The aim of this study is to investigate and explore the potential of MEs as sustained release parenteral drug delivery systems, through their phase transition behaviour in an aqueous environment. Methods: The MEs were developed by constructing pseudoternary phase diagrams using biocompatible Miglyol 812N and a blend of surfactants (Solutol HS 15 and Span 80) and cosurfactant (ethanol). Following the addition of water, the two selected MEs and their derivatives (e.g. CEs or LCs) were subsequently characterised for their rheology, electroconductivity, volume diameter and microstructure. The in vitro phase transition of the MEs to an LC or a CE was monitored by visual observation of the spreadability in water and the microscopic observation for birefringence at the ME/water interface. The physical stability and release kinetics of the progesterone (a lipophilic model drug) loaded MEs were assessed, at three different temperatures (4 °C, 25 °C and 37 °C) and investigated with the use of Franz diffusion cells. The spreadability and drug release profile of the MEs labelled with 99mTc (a hydrophilic model drug) was confirmed using gamma-scintigraphy. Results and Discussion: LC and CE regions were found adjacent to the ME region in the water-rich areas of the phase diagram. Upon the addition of water, the MEs converted from a Newtonian flow with lower viscosities, low conductivities and small droplets (41.8 nm and 69.8 nm) to a pseudo-plastic flow with higher viscosities and altered conductivities and microstructures, suggesting a phase transition into an LC or a CE. The CE-forming ME dispersed rapidly in water, whereas the LC-forming ME remained in a contracted region with an 'LC-shell' forming at the ME/water interface. Owing to the semisolid structure, LC is able to modify the drug diffusion rate through the crystal shell and hence sustain the drug release. Both progesterone-loaded MEs were physically and chemically stable at 4 °C, 25 °C and 37 °C at least for three months. The studies of Franz diffusion cell showed that the LC forming ME resulted in a slower release of progesterone than the CE-forming ME. Gammascintigraphy studies demonstrated the formation of a 'depot' with a significantly slower release of 99mTc from the LC-forming ME than that of the CE-forming ME. Moreover, the gamma-scintigraphic images confirmed that the LC-forming ME spread less in the presence of water compared to the CE-forming ME. This evidence strongly demonstrated in-situ phase transformations from MEs to a CE or an LC upon contact with aqueous medium. Conclusion: From the same pseudoternary phase diagram, MEs can be transitioned into a CE or an LC depending on their composition and location in the phase diagram. Owing to its low viscosity, large solubilising capacity for both water-soluble and oil-soluble drugs, and the potential for an in-situ phase transition to an LC in an aqueous environment, the LC-forming ME could be a promising injectable vehicle for prolonged drug release.
Download or read book Surfactant Science and Technology written by Laurence S. Romsted and published by CRC Press. This book was released on 2014-05-05 with total page 580 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surfactant research explores the forces responsible for surfactant assembly and the critical industrial, medical, and personal applications, including viscosity control, microelectronics, drug stabilization, drug delivery, cosmetics, enhanced oil recovery, and foods. Surfactant Science and Technology: Retrospects and Prospects, "a Festschrift in ho
Download or read book Handbook of Microemulsion Science and Technology written by Promod Kumar and published by CRC Press. This book was released on 1999-07-21 with total page 872 pages. Available in PDF, EPUB and Kindle. Book excerpt: Demonstrating methods for overcoming stability issues in paints, wax dispersions, cosmetics, food products, and other industrial applications, this reference probes theoretical and practical issues surrounding microemulsion science and technology. Featuring the work of 51 international experts and containing almost 1000 instructive tables, equations, and illustrations, this book reviews the performance of, and prospects for, experimental methods such as X-ray diffraction, transmission electron microscopy (TEM), light scattering, small angle neutron scattering, viscosimetry, and nuclear magnetic resonance (NMR) to characterize various aspects of the dispersed phase of microemulsions.
Download or read book Linker based Lecithin Microemulsions as Transdermal Drug Delivery Systems written by Jessica Shuhong Yuan and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The interest in microemulsions as transdermal delivery systems have been motivated by their large surface area for mass transfer, their high solubilization capacity of hydrophobic actives, and their ability to improve skin penetration. Lecithins (mixtures of phospholipids similar to those find in the skin) have been proposed as ideal surfactants in microemulsions due to their skin compatibility. Unfortunately, their incorporation into microemulsions used to require toxic medium-chain alcohols or viscous polymeric co-surfactants. Recently, microemulsion-base "green solvents" were formulated with lecithin and linker molecules. The main objective of this dissertation was to test this concept of linker-based lecithin microemulsions in transdermal delivery. In the first part of this study, linker-based lecithin formulations were developed using soybean lecithin as main surfactant, sorbitol monooleate as lipophilic linker, and caprylic acid/sodium caprylate as hydrophilic linkers. These additives, at the suggested concentration, are safe for cosmetic and pharmaceutical applications. The low toxicity of these formulations was confirmed in cultured human skin tissues. The solubilization and permeation of a common anaesthetic, lidocaine, was evaluated. The concept of "skin" permeability was introduced to account for the differences in solvent-skin partition when comparing different delivery systems. The linker-based lecithin microemulsion produced a substantial absorption of lidocaine into the skin, when compared to a conventional pentanol-lecithin microemulsion. The second part of this study takes advantage of the lidocaine adsorbed in the skin with the linker-based lecithin microemulsion as reservoir for in situ skin patches. The in situ patches were able to release 90% of the lidocaine over 24 hours, which is comparable to the release profile obtained from conventional polymer or gel-based patches. In the third part of this work, the role of surfactant droplets on the transport of lidocaine was studied. A mass balance model that accounted for mass transfer and partition coefficients was introduced. The parameters generated from the model confirm that in most cases the transport through the skin limits the overall penetration of lidocaine. Besides the conventional diffusion mechanism, the results suggest that surfactant droplets, carrying lidocaine, also penetrate into the skin and contribute to the accumulation of the lidocaine in the skin.
Download or read book Microemulsions written by Reza Najjar and published by BoD – Books on Demand. This book was released on 2012-03-16 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: The rapidly increasing number of applications for microemulsions has kept this relatively old topic still at the top point of research themes. This book provides an assessment of some issues influencing the characteristics and performance of the microemulsions, as well as their main types of applications. In chapter 1 a short introduction about the background, various aspects and applications of microemulsions is given. In Part 2 some experimental and modeling investigations on microstructure and phase behavior of these systems have been discussed. The last two parts of book is devoted to discussion on different types of microemulsion's applications, namely, use in drug delivery, vaccines, oil industry, preparation of nanostructured polymeric, metallic and metal oxides materials for different applications.
Download or read book Linker based Lecithin Microemulsions as Transdermal Drug Delivery Systems written by Jessica Shuhong Yuan and published by . This book was released on 2009 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt: The interest in microemulsions as transdermal delivery systems have been motivated by their large surface area for mass transfer, their high solubilization capacity of hydrophobic actives, and their ability to improve skin penetration. Lecithins (mixtures of phospholipids similar to those find in the skin) have been proposed as ideal surfactants in microemulsions due to their skin compatibility. Unfortunately, their incorporation into microemulsions used to require toxic medium-chain alcohols or viscous polymeric co-surfactants. Recently, microemulsion-base "green solvents" were formulated with lecithin and linker molecules. The main objective of this dissertation was to test this concept of linker-based lecithin microemulsions in transdermal delivery.In the first part of this study, linker-based lecithin formulations were developed using soybean lecithin as main surfactant, sorbitol monooleate as lipophilic linker, and caprylic acid/sodium caprylate as hydrophilic linkers. These additives, at the suggested concentration, are safe for cosmetic and pharmaceutical applications. The low toxicity of these formulations was confirmed in cultured human skin tissues. The solubilization and permeation of a common anaesthetic, lidocaine, was evaluated. The concept of "skin" permeability was introduced to account for the differences in solvent-skin partition when comparing different delivery systems. The linker-based lecithin microemulsion produced a substantial absorption of lidocaine into the skin, when compared to a conventional pentanol-lecithin microemulsion. The second part of this study takes advantage of the lidocaine adsorbed in the skin with the linker-based lecithin microemulsion as reservoir for in situ skin patches. The in situ patches were able to release 90% of the lidocaine over 24 hours, which is comparable to the release profile obtained from conventional polymer or gel-based patches. In the third part of this work, the role of surfactant droplets on the transport of lidocaine was studied. A mass balance model that accounted for mass transfer and partition coefficients was introduced. The parameters generated from the model confirm that in most cases the transport through the skin limits the overall penetration of lidocaine. Besides the conventional diffusion mechanism, the results suggest that surfactant droplets, carrying lidocaine, also penetrate into the skin and contribute to the accumulation of the lidocaine in the skin.
Download or read book Application of Nanotechnology in Drug Delivery written by Ali Demir Sezer and published by BoD – Books on Demand. This book was released on 2014-07-25 with total page 556 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book collects reviews and original articles from eminent experts working in the interdisciplinary arena of nanotechnology use in drug delivery. From their direct and recent experience, the readers can achieve a wide vision on the new and ongoing potentialities of nanotechnology application of drug delivery. Since the advent of analytical techniques and capabilities to measure particle sizes in nanometer ranges, there has been tremendous interest in the use of nanoparticles for more efficient methods of drug delivery. On the other hand, this reference discusses advances in design, optimization, and adaptation of gene delivery systems for the treatment of cancer, cardiovascular, pulmonary, genetic, and infectious diseases, and considers assessment and review procedures involved in the development of gene-based pharmaceuticals.
Download or read book Gelled Bicontinuous Microemulsions written by Michaela Laupheimer and published by Springer. This book was released on 2014-06-20 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microemulsions and gels are well-known systems, which play a major role in colloidal and interfacial science. In contrast, the concept of gel microemulsions is still quite new. Gelled microemulsions are highly promising for microemulsion applications in which low viscosity is undesirable, such as administering a drug-delivering microemulsion to a certain area of the skin. It is essential to understand the properties of and structures formed in a system combining microemulsion components and a gelator. This PhD thesis by Michaela Laupheimer provides an in-depth discussion of the phase behavior and sol-gel transition of a microemulsion gelled by a low molecular weight gelator as well as the rheological behavior of a gelled bicontinuous microemulsion. Moreover, the microstructure of the gelled bicontinuous system is fully clarified using techniques like self-diffusion NMR and small angle neutron scattering (SANS). By comparing gelled bicontinuous microemulsions with corresponding non-gelled microemulsions and binary gels, it is demonstrated that bicontinuous microemulsion domains coexist with a gelator network and that the coexisting structures possess no fundamental mutual influence. Hence, gelled bicontinuous microemulsions have been identified as a new type of orthogonal self-assembled system.
Download or read book Handbook of Microemulsions written by Anthony Jenkins and published by . This book was released on 2015-02-25 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents an overview on the various aspects of fundamentals and applications of microemulsions. The increasing utility of microemulsions across various spheres has kept research work in this relatively older field of study to continue at a steady pace. Scientists across various domains are still extremely keen on research in this field. This book brings forth an evaluation of key factors that affect various traits and performance of the microemulsions, including their primary kinds of uses. Various facets and functions of microemulsions and modeling investigations on microstructure and phase behavior of these systems have been discussed. Discussions on uses of diverse kinds of microemulsions, namely, use in drug delivery, vaccines, oil industry, preparation of nanostructured polymeric, metallic and metal oxides materials for different applications have also been provided in this book.
Download or read book Porous Polymeric Materials Derived from Bicontinuous Microemulsions for Drug Delivery written by Fen Ye and published by . This book was released on 2007 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt: "During last decades, significant progress has been made in the field of drug delivery with the development in materials synthesis. Polymer drug delivery systems can realize the prolonged release of drugs, enhance effective drug solubility, protect drug from degradation by enzymes, and reduce drug toxicity. Recently porous materials have been developed as the controlled release host of bioactive reagents, and have shown better controlled release of reagents. Microemulsions are thermodynamically stable, isotropic and transparent dispersions of two normally immiscible fluids stabilized by surfactants and often cosurfactants. Microemulsions have been investigated in a wide range of application including enhanced oil recovery, detergents, bioreactors, drug delivery and to template polymerization. Polymerization of bicontinuous microemulsions can produce materials with defined porous structures. Various surfactants have been reports to form bicontinuous microemulsion for the polymerization of porous materials. Application of biocompaticle surfactants eliminate the need for residual surfactant removal after microemulsion polymerization, and the porous polymeric materials obtained can be used in drug delivery to improve the drug diffusion and enhance the deposition of drug within body. The objective of this study is to develop the biocompatible porous polymeric materials suitable for protein and lipids delivery using methyl methacrylate (MMA) as monomer and 2-hydroxyethyl methacrylate (HEMA) or acrylic acid (AA) as comonomer. Four biocompatible surfactants were tested for the capacity of forming single phase microemulsion at high aqueous content. The Winsor-IV microemulsions formulated with 3:1 HEMA to MMA and surfactant of L1695, T1307 or F127 were studied for the microstructure by viscosity and conductivity measurements. Conductivity and vicsocity measurements confirmed that microstructure of microemulsion was dependent on the aqueous content. With the increase of aqueous content, the structure progressed from W/O droplets, to bicontinuous networks, and finally to O/W droplets. The structure of polymerized microemulsions formulated with various surfactants was studied by scanning electron microscopy (SEM) and the non-invasive freezing point depression (FPD) method. Under SEM, nanopores were observed from the system formulated with 3:1 HEMA to MMA and surfactant of L1695, T1307 or F127. The FPD results were consistent with SEM morphology examination, and demonstrated that the radiuses of nanopores presented in these three systems were mostly in the range of 10-50 nm. Moreover, the nanopores had a distribution dependent on aqueous content. Micropores were observed in the SEM image of the stimuli-responsive partially neutralized 3:2 AA/MMA/10 % F77 system. The incorporation of drugs didn't change the microstructure of polymers. Polymers derived from microemulsions stabilized by four surfactants were applied to encapsulate drugs, and the drug release profiles were investigated. The nanoporous polymer particle suspension exhibited controlled release of Rhodamine B. The release rate was four times lower than the drug loaded to 10% F127 solution. Nanoporous monoliths derived from L1695 or T1307 stabilize microemulsions could realize the gradual release of B-galactosidase within 6 hours. The pH of precursor microemulsion stablized by T1307 was 8, and higher than that of the L1695 stabilized microemulsion. Enzymes released from L1695 system displayed higher apparent activity since lower pH favors enzyme catalysis when pH is larger than 5. The partially neutralized system demonstrated swelling behavior dependent on the pH of aqueous medium. Lipase lost activity in pH=1.2 medium, while lipase released from pH-sensitive system in pH=6.8 buffer showed increased activity over time. The release of lipase because stable after 6 hours. These release profiles suggested that the porous systems could achieve prolonged release of drugs, and all the systems are promising for the application in drug deliver."--Abstract.
