Download or read book Relaxation Dynamics and Crystallization Kinetics of Glass forming Drugs written by Guadalupe Natalia Ruiz and published by . This book was released on 2018 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt: Glassy phases play an important role in our daily life and in many industries such as the food, pharmaceutical, and construction and are responsible for certain vital mechanisms in living species. Whereas crystals are solid phases that show periodicity of the constituent atoms or molecules, glasses are disordered solids that lack long-range positional order but behave mechanically like solids. Chapter 1 of the current thesis presents an introduction to the characteristics and dynamics of glassy phases. How they are derived from the liquid phase, and how they transform into the crystalline solid phase, thermodynamically more stable. The temperature at which a liquid transforms to the amorphous (glassy) phase is called the glass transition temperature, Tg. Along this thesis the relaxation dynamics of prilocaine (PLC) and stiripentol (STP), and the isothermal crystallization process of the latter have been experimentally studied. Both PLC and STP are drugs used in medical applications mainly as anesthesia and for the treatment of epilepsy, respectively. The studied materials have been analyzed by Broadband Dielectric Spectroscopy (BDS), Differential Scanning Calorimetry, X-Ray diffraction, Raman and I.R spectroscopy and confocal microscopy. The physical principles of BDS, the main experimental tool employed, are presented in Chapter 2. The details of the experimental set-ups are stated in Chapter 3. In the case of a pharmaceutical product, being able to control and foresee the aggregation phase and dissolution rate of the substance is vital. Many drugs are poorly soluble in water and thus, in biological media. The glass state of a drug is a non-equilibrium state that presents higher free energy than the crystal. This implies, that a glassy drug dissolves more rapidly and can be absorbed in larger amounts. Nevertheless, the higher free energy of glassy phases represents at the same time a major problem for shelf-life, since metastable phases are prone to spontaneously transforming into the stable crystalline state. This is a major problem, since wrong dosage or agglomeration of a drug could render it useless or toxic for the human body. Understanding the glass and crystallization dynamics of drugs, and their interaction with water is key to develop more efficient products. Water is the universal biological solvent. For most materials the addition of water leads to a decrease in viscosity, or equivalently, an increase of molecular mobility, resulting in a lower glass transition temperature Tg (the higher the water content the lower the Tg). This is referred to as the plasticizing effect of water. Chapter 4 presents a detailed analysis of both pure and hydrated prilocaine. Results show that the addition of water to PLC leads to the formation of PLC-water complexes, possibly water-bridged monomers or dimers that increase Tg. This antiplasticizing effect of water on the molecular mobility of a simple glass former represents a significant exception to the alleged universality of water as drug plasticizer. The physico-chemical origins of this behavior have been confirmed by studying the effect of confinement of the pure and hydrated drug in the pores of a nonporous structure (Chapter 5). In the case of STP, not only the glassy dynamics were studied, but also the crystallization process (Chapter 6). A sublinear correlation between the characteristic crystal-growth time and the relaxation time of the cooperative relaxation dynamics of stiripentol was found. This correlation was observed also in other substances, which suggests that it is a general correlation at temperatures above Tg. This may allow predicting a substance's crystallization time as a function of temperature. The results of this thesis provide valuable insight into the kinetics and relaxation dynamics, as well as the phase stability, of both studied drugs that could be general to other amorphous drugs. Global conclusions are outlined in Chapter 7.
Download or read book Crystallization and Relaxation Kinetics in Metallic Glass forming Systems written by Mark Stringe and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Amorphous Drugs written by Marzena Rams-Baron and published by Springer. This book was released on 2018-02-09 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book explains theoretical and technological aspects of amorphous drug formulations. It is intended for all those wishing to increase their knowledge in the field of amorphous pharmaceuticals. Conversion of crystalline material into the amorphous state, as described in this book, is a way to overcome limited water solubility of drug formulations, in this way enhancing the chemical activity and bioavailability inside the body. Written by experts from various fields and backgrounds, the book introduces to fundamental physical aspects (explaining differences between the ordered and the disordered solid states, the enhancement of solubility resulting from drugs amorphization, physical instability and how it can be overcome) as well as preparation and formulation procedures to produce and stabilize amorphous pharmaceuticals. Readers will thus gain a well-funded understanding and find a multi-faceted discussion of the properties and advantages of amorphous drugs and of the challenges in producing and stabilizing them. The book is an ideal source of information for researchers and students as well as professionals engaged in research and development of amorphous pharmaceutical products.
Download or read book Fast Scanning Calorimetry written by Christoph Schick and published by Springer. This book was released on 2016-06-28 with total page 796 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the past decades, the scan rate range of calorimeters has been extended tremendously at the high end, from approximately 10 up to 10 000 000 °C/s and more. The combination of various calorimeters and the newly-developed Fast Scanning Calorimeters (FSC) now span 11 orders of magnitude, by which many processes can be mimicked according to the time scale(s) of chemical and physical transitions occurring during cooling, heating and isothermal stays in case heat is exchanged. This not only opens new areas of research on polymers, metals, pharmaceuticals and all kinds of substances with respect to glass transition, crystallization and melting phenomena, it also enables in-depth study of metastability and reorganization of samples on an 1 to 1000 ng scale. In addition, FSC will become a crucial tool for understanding and optimization of processing methods at high speeds like injection molding. The book resembles the state-of-the art in Thermal Analysis & Calorimetry and is an excellent starting point for both experts and newcomers in the field.
Download or read book The Glass Transition written by Ernst-Joachim Donth and published by . This book was released on 2014-09-01 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Glass Transition written by E. Donth and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 433 pages. Available in PDF, EPUB and Kindle. Book excerpt: Describes and interrelates the following processes: cooperative alpha processes in a cold liquid, structural relaxation in the glass near Tg, the Johari-Goldstein beta process, the Williams-Götze process in a warm liquid, fast nonactivated cage rattling and boson peak, and ultraslow Fischer modes.
Download or read book Amorphous Solid Dispersions written by Navnit Shah and published by Springer. This book was released on 2014-11-21 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume offers a comprehensive guide on the theory and practice of amorphous solid dispersions (ASD) for handling challenges associated with poorly soluble drugs. In twenty-three inclusive chapters, the book examines thermodynamics and kinetics of the amorphous state and amorphous solid dispersions, ASD technologies, excipients for stabilizing amorphous solid dispersions such as polymers, and ASD manufacturing technologies, including spray drying, hot melt extrusion, fluid bed layering and solvent-controlled micro-precipitation technology (MBP). Each technology is illustrated by specific case studies. In addition, dedicated sections cover analytical tools and technologies for characterization of amorphous solid dispersions, the prediction of long-term stability, and the development of suitable dissolution methods and regulatory aspects. The book also highlights future technologies on the horizon, such as supercritical fluid processing, mesoporous silica, KinetiSol®, and the use of non-salt-forming organic acids and amino acids for the stabilization of amorphous systems. Amorphous Solid Dispersions: Theory and Practice is a valuable reference to pharmaceutical scientists interested in developing bioavailable and therapeutically effective formulations of poorly soluble molecules in order to advance these technologies and develop better medicines for the future.
Download or read book Disorder Effects on Relaxational Processes written by Ranko Richert and published by . This book was released on 1994 with total page 776 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Crystallization Dynamics in Glass forming Systems written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Crystallization under far-from-equilibrium conditions is investigated for two different scenarios: crystallization of the metallic glass alloy Cu50Zr50 and solidification of a transparent organic compound, o-terphenyl. For Cu50Zr50, crystallization kinetics are quanti ed through a new procedure that directly fits thermal analysis data to the commonly utilized JMAK model. The phase evolution during crystallization is quantified through in-situ measurements (HEXRD, DSC) and ex-situ microstructural analysis (TEM, HRTEM). The influence of chemical partitioning, diffusion, and crystallographic orientation on this sequence are examined. For o-terphenyl, the relationship between crystal growth velocity and interface undercooling is systematically studied via directional solidification.
Download or read book Molecular Dynamics and Relaxation Phenomena in Glasses written by Thomas Dorfmüller and published by Springer. This book was released on 1987-04-23 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the proceedings of a workshop on glass-forming liquids held at the University of Bielefeld in 1985. The aim of the meeting was to seek unifying interpretations which may apply to all glass-forming materials like inorganic and polymer glasses. Also, new data was presented and modern interpretations were applied which represent the state-of-the-art knowledge about the unusual physical properties of these chemically-diverse glass-forming materials. The book should be of interest to specialists in the subject, to polymer scientists, glass technologists and materials scientists, but also - and most importantly - to researchers and teachers who wish to become informed on some of the most recent fundamental research in the fields.
Download or read book Molecular Dynamics and Relaxation Phenomena in Glasses written by Thomas Dorfmüller and published by . This book was released on 1987 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the proceedings of a workshop on glass-forming liquids held at the University of Bielefeld in 1985. The aim of the meeting was to seek unifying interpretations which may apply to all glass-forming materials like inorganic and polymer glasses. Also, new data was presented and modern interpretations were applied which represent the state-of-the-art knowledge about the unusual physical properties of these chemically-diverse glass-forming materials. The book should be of interest to specialists in the subject, to polymer scientists, glass technologists and materials scientists, but also - and most importantly - to researchers and teachers who wish to become informed on some of the most recent fundamental research in the fields.
Download or read book Stability of Amorphous Pharmaceuticals Prediction of Onset of Crystallization Using Experimental Relaxation Times written by Chandan Bhugra and published by . This book was released on 2007 with total page 275 pages. Available in PDF, EPUB and Kindle. Book excerpt: Onset times to crystallization were coupled with dielectric relaxation times in the above Tg temperature range for all compounds (indomethacin, felodipine and flopropione) except nifedipine. Good quantitative agreement between predicted and experimental crystallization onset times was obtained for two compounds (indomethacin and flopropione) at two temperature points below Tg. Crystallization growth rates also coupled with the measured dielectric relaxation times. Though the above protocol may be used as a first step in developing the stability testing protocol for crystallization from amorphous state, clearly compound specific characteristics and critical processing conditions play a significant role in successful use of the protocol.
Download or read book Inhalation Aerosols written by Anthony J. Hickey and published by CRC Press. This book was released on 2019-03-21 with total page 546 pages. Available in PDF, EPUB and Kindle. Book excerpt: Inhalation aerosols continue to be the basis for successful lung therapy for several diseases, with therapeutic strategies and the range of technology significantly evolving in recent years. In response, this third edition takes a new approach to reflect the close integration of technology with its application. After briefly presenting the general considerations that apply to aerosol inhalation, the central section of the book uses the focus on disease and therapeutic agents to illustrate the application of specific technologies. The final integrated strategies section draws the major points from the applications for disease targets and drug products.
Download or read book Introduction to Glass Science and Technology written by James E Shelby and published by Royal Society of Chemistry. This book was released on 2015-11-06 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a concise and inexpensive introduction for an undergraduate course in glass science and technology. The level of the book has deliberately been maintained at the introductory level to avoid confusion of the student by inclusion of more advanced material, and is unique in that its text is limited to the amount suitable for a one term course for students in materials science, ceramics or inorganic chemistry. The contents cover the fundamental topics of importance in glass science and technology, including glass formation, crystallization, phase separation and structure of glasses. Additional chapters discuss the most important properties of glasses, including discussion of physical, optical, electrical, chemical and mechanical properties. A final chapter provides an introduction to a number of methods used to form technical glasses, including glass sheet, bottles, insulation fibre, optical fibres and other common commercial products. In addition, the book contains discussion of the effects of phase separation and crystallization on the properties of glasses, which is neglected in other texts. Although intended primarily as a textbook, Introduction to Glass Science and Technology will also be invaluable to the engineer or scientist who desires more knowledge regarding the formation, properties and production of glass.
Download or read book Drug Delivery Aspects written by Ranjita Shegokar and published by Academic Press. This book was released on 2020-03-27 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt: Drug Delivery Aspects reviews additional features of drug delivery systems, along with the standard formulation development, like preclinical testing, conversion into solid dosage forms, roles of excipients and polymers used on stability and sterile processing. There is a focus on formulation engineering and related large scale (GMP) manufacturing, regulatory, and functional aspects of drug delivery systems. A detailed discussion on biologics and vaccines gives insights to readers on new developments in this direction. The series Expectations and Realities of Multifunctional Drug Delivery Systems examines the fabrication, optimization, biological aspects, regulatory and clinical success of wide range of drug delivery carriers. This series reviews multifunctionality and applications of drug delivery systems, industrial trends, regulatory challenges and in vivo success stories. Throughout the volumes discussions on diverse aspects of drug delivery carriers, such as clinical, engineering, and regulatory, facilitate insight sharing across expertise area and form a link for collaborations between industry-academic scientists and clinical researchers. Expectations and Realities of Multifunctional Drug Delivery Systems connects formulation scientists, regulatory experts, engineers, clinical experts and regulatory stake holders. The wide scope of the book ensures it as a valuable reference resource for researchers in both academia and the pharmaceutical industry who want to learn more about drug delivery systems. Encompasses engineering and large-scale manufacturing of nanocarriers Considers preclinical, regulatory and ethical guidelines on nanoparticles Contains in-depth discussions on delivery of biologics, vaccines and sterilisation Industrial view on solid dispersions, milling techniques
Download or read book Rapidly Quenched Metals written by S Steeb and published by Elsevier. This book was released on 2012-12-02 with total page 1163 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rapidly Quenched Metals, Volume I covers the proceedings of the Fifth International Conference on Rapidly Quenched Metals, held in Wurzburg, Germany on September 3-7, 1984. The book focuses on amorphous and crystalline metals formed by rapid quenching from the melt. The selection first covers the scope and trends of developments in rapid solidification technology, rapid solidification, and undercooling of liquid metals by rapid quenching. Discussions focus on experimental method, powders, strip, particulate production, consolidation, and alloys and alloy systems. The text then examines the solidification of undercooled liquid alloys entrapped in solid; crystallization kinetics in undercooled droplets; and grain refinement in bulk undercooled alloys. The manuscript tackles the undercooling of niobium-germanium alloys in a 100 meter drop tube; influence of process parameters on the cooling rate of the meltspinning process; and the mechanism of ribbon formation in melt-spun copper and copper-zirconium. The formation and structure of thick sections of rapidly-solidified material by incremental deposition and production of ultrafine dispersions of rare earth oxides in Ti alloys using rapid solidification are also mentioned. The selection is a valuable reference for physicists, chemists, physical metallurgists, and engineers.
Download or read book Disordered Pharmaceutical Materials written by Marc Descamps and published by John Wiley & Sons. This book was released on 2016-08-08 with total page 542 pages. Available in PDF, EPUB and Kindle. Book excerpt: A one-stop resource for researchers, developers, and post graduate students in pharmaceutical science. This handbook and ready reference provides detailed, but not overloaded information -- presenting the topic without unnecessarily complex formalism. As such, it gives a systematic and coherent overview of disordered materials for pharmaceutical applications, covering fundamental aspects, as well as preparation and characterization techniques for the target-oriented development of drug delivery systems based on disordered crystals and amorphous solids. Special attention is paid to examine the different facets and levels of disorder in their structural and dynamic aspects as well as the effect of disorder on dissolution and stability. Chapters on processing induced disorder and on patenting issues round off the book. As a result the book helps overcoming the challenges of using these materials in the pharmaceutical industry. For pharmaceutical and medicinal chemists, materials scientists, clinical physicists, and pharmaceutical laboratories looking to make better and more potent pharmaceuticals.
