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Drug Delivery Strategies for Poorly Water-Soluble Drugs by Dionysios Douroumis,Alfred Fahr Pdf
Many newly proposed drugs suffer from poor water solubility, thus presenting major hurdles in the design of suitable formulations for administration to patients. Consequently, the development of techniques and materials to overcome these hurdles is a major area of research in pharmaceutical companies. Drug Delivery Strategies for Poorly Water-Soluble Drugs provides a comprehensive overview of currently used formulation strategies for hydrophobic drugs, including liposome formulation, cyclodextrin drug carriers, solid lipid nanoparticles, polymeric drug encapsulation delivery systems, self–microemulsifying drug delivery systems, nanocrystals, hydrosol colloidal dispersions, microemulsions, solid dispersions, cosolvent use, dendrimers, polymer- drug conjugates, polymeric micelles, and mesoporous silica nanoparticles. For each approach the book discusses the main instrumentation, operation principles and theoretical background, with a focus on critical formulation features and clinical studies. Finally, the book includes some recent and novel applications, scale-up considerations and regulatory issues. Drug Delivery Strategies for Poorly Water-Soluble Drugs is an essential multidisciplinary guide to this important area of drug formulation for researchers in industry and academia working in drug delivery, polymers and biomaterials.
Robert O. Williams III,Alan B. Watts,Dave A. Miller
Author : Robert O. Williams III,Alan B. Watts,Dave A. Miller Publisher : Springer Science & Business Media Page : 656 pages File Size : 41,5 Mb Release : 2011-12-04 Category : Medical ISBN : 9781461411444
Formulating Poorly Water Soluble Drugs by Robert O. Williams III,Alan B. Watts,Dave A. Miller Pdf
This volume is intended to provide the reader with a breadth of understanding regarding the many challenges faced with the formulation of poorly water-soluble drugs as well as in-depth knowledge in the critical areas of development with these compounds. Further, this book is designed to provide practical guidance for overcoming formulation challenges toward the end goal of improving drug therapies with poorly water-soluble drugs. Enhancing solubility via formulation intervention is a unique opportunity in which formulation scientists can enable drug therapies by creating viable medicines from seemingly undeliverable molecules. With the ever increasing number of poorly water-soluble compounds entering development, the role of the formulation scientist is growing in importance. Also, knowledge of the advanced analytical, formulation, and process technologies as well as specific regulatory considerations related to the formulation of these compounds is increasing in value. Ideally, this book will serve as a useful tool in the education of current and future generations of scientists, and in this context contribute toward providing patients with new and better medicines.
Poorly Soluble Drugs by Gregory K. Webster,Robert G. Bell,J. Derek Jackson Pdf
This book is the first text to provide a comprehensive assessment of the application of fundamental principles of dissolution and drug release testing to poorly soluble compounds and formulations. Such drug products are, vis-à-vis their physical and chemical properties, inherently incompatible with aqueous dissolution. However, dissolution methods are required for product development and selection, as well as for the fulfillment of regulatory obligations with respect to biopharmaceutical assessment and product quality understanding. The percentage of poorly soluble drugs, defined in classes 2 and 4 of the Biopharmaceutics Classification System (BCS), has significantly increased in the modern pharmaceutical development pipeline. This book provides a thorough exposition of general method development strategies for such drugs, including instrumentation and media selection, the use of compendial and non-compendial techniques in product development, and phase-appropriate approaches to dissolution development. Emerging topics in the field of dissolution are also discussed, including biorelevant and biphasic dissolution, the use on enzymes in dissolution testing, dissolution of suspensions, and drug release of non-oral products. Of particular interest to the industrial pharmaceutical professional, a brief overview of the formulation and solubilization techniques employed in the development of BCS class 2 and 4 drugs to overcome solubility challenges is provided and is complemented by a collection of chapters that survey the approaches and considerations in developing dissolution methodologies for enabling drug delivery technologies, including nanosuspensions, lipid-based formulations, and stabilized amorphous drug formulations.
Robert O. Williams III,Daniel A. Davis Jr.,Dave A. Miller
Author : Robert O. Williams III,Daniel A. Davis Jr.,Dave A. Miller Publisher : Springer Nature Page : 701 pages File Size : 49,9 Mb Release : 2022-05-19 Category : Medical ISBN : 9783030887193
Formulating Poorly Water Soluble Drugs by Robert O. Williams III,Daniel A. Davis Jr.,Dave A. Miller Pdf
The objective of this third edition is to consolidate within a single text the most current knowledge, practical methods, and regulatory considerations pertaining to formulations development with poorly water-soluble molecules. A pharmaceutical scientist’s approach toward solubility enhancement of a poorly water-soluble molecule typically includes detailed characterization of the compound’s physiochemical properties, solid-state modifications, advanced formulation design, non-conventional process technologies, advanced analytical characterization, and specialized product performance analysis techniques. The scientist must also be aware of the unique regulatory considerations pertaining to the non-conventional approaches often utilized for poorly water-soluble drugs. One faced with the challenge of developing a drug product from a poorly soluble compound must possess at a minimum a working knowledge of each of the above mentioned facets and detailed knowledge of most. In light of the magnitude of the growing solubility problem to drug development, this is a significant burden especially when considering that knowledge in most of these areas is relatively new and continues to develop.
Poorly Soluble Drugs by Gregory K. Webster,Robert G. Bell,J. Derek Jackson Pdf
This book is the first text to provide a comprehensive assessment of the application of fundamental principles of dissolution and drug release testing to poorly soluble compounds and formulations. Such drug products are, vis-à-vis their physical and chemical properties, inherently incompatible with aqueous dissolution. However, dissolution methods are required for product development and selection, as well as for the fulfillment of regulatory obligations with respect to biopharmaceutical assessment and product quality understanding. The percentage of poorly soluble drugs, defined in classes 2 and 4 of the Biopharmaceutics Classification System (BCS), has significantly increased in the modern pharmaceutical development pipeline. This book provides a thorough exposition of general method development strategies for such drugs, including instrumentation and media selection, the use of compendial and non-compendial techniques in product development, and phase-appropriate approaches to dissolution development. Emerging topics in the field of dissolution are also discussed, including biorelevant and biphasic dissolution, the use on enzymes in dissolution testing, dissolution of suspensions, and drug release of non-oral products. Of particular interest to the industrial pharmaceutical professional, a brief overview of the formulation and solubilization techniques employed in the development of BCS class 2 and 4 drugs to overcome solubility challenges is provided and is complemented by a collection of chapters that survey the approaches and considerations in developing dissolution methodologies for enabling drug delivery technologies, including nanosuspensions, lipid-based formulations, and stabilized amorphous drug formulations.
Teaches future and current drug developers the latest innovations in drug formulation design and optimization This highly accessible, practice-oriented book examines current approaches in the development of drug formulations for preclinical and clinical studies, including the use of functional excipients to enhance solubility and stability. It covers oral, intravenous, topical, and parenteral administration routes. The book also discusses safety aspects of drugs and excipients, as well as regulatory issues relevant to formulation. Innovative Dosage Forms: Design and Development at Early Stage starts with a look at the impact of the polymorphic form of drugs on the preformulation and formulation development. It then offers readers reliable strategies for the formulation development of poorly soluble drugs. The book also studies the role of reactive impurities from the excipients on the formulation shelf life; preclinical formulation assessment of new chemical entities; and regulatory aspects for formulation design. Other chapters cover innovative formulations for special indications, including oncology injectables, delayed release and depot formulations; accessing pharmacokinetics of various dosage forms; physical characterization techniques to assess amorphous nature; novel formulations for protein oral dosage; and more. -Provides information that is essential for the drug development effort -Presents the latest advances in the field and describes in detail innovative formulations, such as nanosuspensions, micelles, and cocrystals -Describes current approaches in early pre-formulation to achieve the best in vivo results -Addresses regulatory and safety aspects, which are key considerations for pharmaceutical companies -Includes case studies from recent drug development programs to illustrate the practical challenges of preformulation design Innovative Dosage Forms: Design and Development at Early Stage provides valuable benefits to interdisciplinary drug discovery teams working in industry and academia and will appeal to medicinal chemists, pharmaceutical chemists, and pharmacologists.
Emulsions and Nanosuspensions for the Formulation of Poorly Soluble Drugs by Rainer H. Müller,Simon Benita,Bernhard H. L. Böhm Pdf
Explore possible new approaches for overcoming poorly soluble drugs - a challenge to drug formulation work and an increasing problem. Many newly developed drugs are poorly soluble, very often simultaneously in aqueous and in organic media. Emulsions and Nanosuspensions for the Formulation of Poorly Soluble Drugs aims to: review the possibilities, limitations and future perspectives of emulsions as drug carriers considering technology from other than the phamaceutical industry (i.e food industry). show the production technology of nanosuspensions, explain the special dissolution properties (i.e. increased saturation solubility) and increased dissolution velocity (theory), and cover the possible applications. present the theory of high pressure homogenization and high pressure extrusion in dispersion techniques, including examples of applications and size measurements in concentrated dispersions.
Poorly Soluble Drugs by Gregory K. Webster,J. Derek Jackson,Robert G. Bell Pdf
This book is the first text to provide a comprehensive assessment of the application of fundamental principles of dissolution and drug release testing to poorly soluble compounds and formulations. Such drug products are, vis-à-vis their physical and chemical properties, inherently incompatible with aqueous dissolution. However, dissolution methods are required for product development and selection, as well as for the fulfillment of regulatory obligations with respect to biopharmaceutical assessment and product quality understanding. The percentage of poorly soluble drugs, defined in classes 2 and 4 of the Biopharmaceutics Classification System (BCS), has significantly increased in the modern pharmaceutical development pipeline. This book provides a thorough exposition of general method development strategies for such drugs, including instrumentation and media selection, the use of compendial and non-compendial techniques in product development, and phase-appropriate approaches to dissolution development. Emerging topics in the field of dissolution are also discussed, including biorelevant and biphasic dissolution, the use on enzymes in dissolution testing, dissolution of suspensions, and drug release of non-oral products. Of particular interest to the industrial pharmaceutical professional, a brief overview of the formulation and solubilization techniques employed in the development of BCS class 2 and 4 drugs to overcome solubility challenges is provided and is complemented by a collection of chapters that survey the approaches and considerations in developing dissolution methodologies for enabling drug delivery technologies, including nanosuspensions, lipid-based formulations, and stabilized amorphous drug formulations.
Oral Lipid-Based Formulations by David J. Hauss Pdf
Oral lipid-based formulations are attracting considerable attention due to their capacity to facilitate gastrointestinal absorption and reduce or eliminate the effect of food on the absorption of poorly water-soluble, lipophilic drugs. Despite the obvious and demonstrated utility of these formulations for addressing a persistent and growing problem of major significance, the pharmaceutical industry has been slow to apply and further develop this technology. This title provides a comprehensive summary of the theoretical and practical aspects of oral lipid-based formulations for use in industry, and provides further insights into a developing technology expected to assume increasing prominence in years to come.
Solubility is the property of a solid, liquid, or gaseous chemical substance called solute to dissolve in a solid, liquid, or gaseous solvent to form a homogeneous solution of the solute in the solvent. The solubility of a substance fundamentally depends on the solvent used as well as on temperature and pressure. The extent of solubility of a substance in a specific solvent is measured as the saturation concentration where adding more solute does not increase its concentration in the solution. Solubility also plays a major role for other dosage forms like parenteral formulations as well. Many newly proposed drugs suffer from poor water solubility, thus presenting major hurdles in the design of suitable formulations for administration to patients. Consequently, the development of techniques and materials to overcome these hurdles is a major area of research in pharmaceutical companies. This book provides a comprehensive overview of currently used formulation strategies for hydrophobic drugs discusses the main instrumentation, operation principles and theoretical background, with a focus on critical formulation features and clinical studies. It provides a comprehensive assessment of the application of fundamental principles of dissolution and drug release testing to poorly soluble compounds and formulations. Over 40% of new chemical entities developed in pharmaceutical industry are practically insoluble in water. These poorly water soluble drugs having slow drug absorption leads to inadequate and variable bioavailability and gastrointestinal mucosal toxicity. For orally administered drugs solubility is the most important one rate limiting parameter to achieve their desired concentration in systemic circulation for pharmacological response. Problem of solubility is a major challenge for formulation scientist. The improvement of drug solubility thereby its oral bioavailability remains one of the most challenging aspects of drug development process especially for oral-drug delivery system.
Properties and Formulation: From Theory to Real-World Application Scientists have attributed more than 40 percent of the failures in new drug development to poor biopharmaceutical properties, particularly water insolubility. Issues surrounding water insolubility can postpone or completely derail important new drug development. Even the much-needed reformulation of currently marketed products can be significantly affected by these challenges. More recently it was reported that the percentage increased to 90% for the candidates of new chemical entities in the discovery stage and 75% for compounds under development. In the most comprehensive resource on the topic, this third edition of Water-Insoluble Drug Formulation brings together a distinguished team of experts to provide the scientific background and step-by-step guidance needed to deal with solubility issues in drug development. Twenty-three chapters systematically describe the detailed discussion on solubility theories, solubility prediction models, the aspects of preformulation, biopharmaceutics, pharmacokinetics, regulatory, and discovery support of water-insoluble drugs to various techniques used in developing delivery systems for water-insoluble drugs. This book includes more than 15 water-insoluble drug delivery systems or technologies, illustrated with case studies and featuring oral and parenteral applications. Highlighting the most current information and data available, this seminal volume reflects the significant progress that has been made in nearly all aspects of this field. The aim of this book is to provide a handy reference for pharmaceutical scientists in the handling of formulation issues related to water-insoluble drugs. In addition, this book may be useful to pharmacy and chemistry undergraduate students and pharmaceutical and biopharmaceutical graduate students to enhance their knowledge in the techniques of drug solubilization and dissolution enhancement.
Oral Lipid-Based Formulations by David J. Hauss Pdf
Oral lipid-based formulations are attracting considerable attention due to their capacity to facilitate gastrointestinal absorption and reduce or eliminate the effect of food on the absorption of poorly water-soluble, lipophilic drugs. Despite the obvious and demonstrated utility of these formulations for addressing a persistent and growing problem
Solubility enhancement of poorly water-soluble drugs by solid dispersion by Adela Kalivoda Pdf
Summary Solid dispersions are a promising approach for controlled release drug delivery systems as both the bioavailability enhancement of poorly water-soluble drugs as well as the sustained release of water-soluble drugs are possible to optimize their in vivo performance. Different methods for the manufacture of solid dispersion systems have been introduced in literature. In the present work, two methods are compared: hot-melt extrusion and ultrasound-assisted compaction technique. Various carrier systems and drugs with different physicochemical properties are applied to investigate the feasibility of the technologies for pharmaceutical formulation. The formulations are compared to the corresponding untreated physical blends of the components regarding their solid state structure and dissolution behavior to assess the effect of the manufacturing technique. Ultrasound-assisted compaction technique improves the initial dissolution rate of fenofibrate, a poorly water-soluble model drug. The crystalline API is partially converted into its amorphous state. As equivalent results can be achieved if the polymers are added directly to the dissolution medium, the dissolution enhancement is attributed to an improved wettability of the drug. A statistical design of experiments is employed to investigate the effect of the process parameters on the results. Difficulties are encountered in the determination of process parameters which result in an optimal outcome. The process is very sensitive to the smallest changes of settings, for example of the position of the sonotrode. Additionally, the delivery of ultrasound energy is inhomogeneous. There is no or only insufficient user control of these parameters available. Furthermore, the duration of ultrasound energy delivery which is identified as a crucial parameter cannot be set by the user. The variable factors ultrasound energy, pressure of the lower piston and pressure of the upper piston affect the defined responses in the opposite direction. Hence, there are no settings which result in a satisfactory outcome. A strong influence of the material characteristics on the process is observed leading to a batch to batch variability. Due to an insufficient reproducibility of results, the application of the technology cannot be recommended in its current state in the pharmaceutical formulation development and/or production. Improvements in homogeneity of energy delivery, process monitoring, user control and amount of leakage are mandatory for an acceptable performance and a future application in the pharmaceutical sector. The polymers COP, HPMC and PVCL-PVAc-PEG are well suitable as carriers for hot-melt extruded formulations of fenofibrate. All three extrudates are amorphous one-phase systems with the drug molecularly dispersed in the polymer. The enhancement of the initial dissolution rate and the maximum concentration level achieved are dependent on the applied carrier system. Supersaturation levels of up to 12.1 times are reached which are not stable due to recrystallization processes. The application of blends of polymers as carriers reduces the decrease rate after cmax. Because of water absorption and polymer relaxation, the overall dissolution performance decreases with increasing storage times which can be avoided through an optimization of the packaging. If oxeglitazar is used as API, the initial dissolution rate of the extrudates is below that of the untreated drug, with the exception of the ternary blend of COP, HPMC and oxeglitazar which shows a substance-specific super-additive effect. In contrast to the other extrudates, the formulation of PVCL-PVAc-PEG and oxeglitazar does not form a molecularly dispersed solid solution of the drug in the carrier. Instead, an amorphous two-phase system is present. No changes are observed after storage, presumably due to higher glass transition temperatures of the hot-melt extruded systems which are considerably above those of the corresponding fenofibrate extrudates. With felodipine as API, the dissolution profile is enhanced with COP as single carrier. If HPMC or PVCL-PVAc-PEG is used as single or additional polymeric carriers, the dissolution is equivalent (HPMC) or lower (PVCL-PVAc-PEG) than that of the pure drug although molecularly disperse systems are present in all cases. Out of the two investigated methods only hot-melt extrusion is a suitable technology to manufacture solid dispersions with an improved dissolution behavior. The dissolution profile of the extrudates can be influenced by adding polymers with differing physicochemical characteristics. Predictions on the dissolution behavior of the extrudates with polymeric blends as carriers can be made if there is knowledge on the dissolution profiles of the corresponding single polymeric extrudates. Due to substance-specific effects, the results are not transferable from drug to drug. Even so, the data are promising as the release behavior of the manufactured extrudates can be easily modified and readily adapted to one's needs. Further research will have to be conducted to verify the concept and the relevance of the results in vivo. Zusammenfassung Feste Dispersionen sind ein vielversprechender Ansatz zur Herstellung von Drug Delivery-Systemen mit kontrollierter Wirkstofffreisetzung, da sie sowohl die Bioverfügbarkeit schlecht wasserlöslicher Arzneistoffe verbessern als auch die Freisetzung gut wasserlöslicher Arzneistoffe verzögern können und so deren in vivo Verhalten optimieren. Verschiedene Herstellungsmethoden wurden in der Literatur vorgestellt. In der vorliegenden Arbeit werden zwei Technologien miteinander verglichen: Schmelzextrusion und Ultraschall gestützte Verpressung (USAC). Verschiedene Trägersysteme und Arzneistoffe mit unterschiedlichen physikochemischen Eigenschaften werden untersucht, um die Einsatzmöglichkeit im pharmazeutischen Bereich zu überprüfen. Die Struktur der hergestellten Systeme und deren Freisetzungsverhalten werden mit den physikalischen Mischungen der Komponenten verglichen, um den Einfluss der Formulierung zu bestimmen. Durch USAC wird die initiale Freisetzungsrate von Fenofibrat, einem schlecht wasserlöslichen Modellarzneistoff, verbessert. Eine teilweise Umwandlung vom kristallinen in den amorphen Zustand tritt auf. Vergleichbare Ergebnisse werden bei einer Polymerzugabe zum Freisetzungsmedium erreicht; daher wird davon ausgegangen, dass vor allem eine verbesserte Benetzbarkeit des Arzneistoffs eine Rolle spielt. Mittels statistischer Versuchsplanung wird der Einfluss der verschiedenen Prozessparameter untersucht. Die Einstellung der Prozessparameter, um ein optimales Ergebnis zu erhalten, gestaltet sich schwierig. Der Prozess reagiert auf kleinste Veränderungen, zum Beispiel der Position der Sonotrode, überaus sensitiv. Außerdem wird die Ultraschallenergie nicht homogen übertragen. Die Kontrolle dieser Parameter durch den Anwender ist nicht oder nur unzureichend möglich. Ebenso kann die Dauer der Ultraschallapplizierung, die essentiell für den Prozess ist, nicht eingestellt werden. Die Prozessparameter Ultraschallenergie, Unterstempeldruck und Sonotrodendruck beeinflussen die Zielgrößen in entgegengesetzter Richtung. Daher gibt es keine Einstellung, die für alle Zielgrößen optimale Ergebnisse liefert. Zusätzlich ist der Prozess stark abhängig von den Eigenschaften des verwendeten Materials: Die Verwendung unterschiedlicher Polymerchargen macht eine Anpassung der Prozessparameter notwendig, um vergleichbare Ergebnisse zu erhalten. Eine ausreichende Reproduzierbarkeit der Ergebnisse für einen Einsatz dieser Technologie in Formulierungsentwicklung oder Produktion ist nicht gegeben. Eine homogene Ultraschallenergiezufuhr sowie Verbesserungen der Prozessüberwachung, der Benutzerkontrolle und eine Verminderung der austretenden Materialmenge sind für eine akzeptable Leistung und eine zukünftige Anwendung im pharmazeutischen Bereich zwingend erforderlich. Die Polymere COP, HPMC, PVCL-PVAc-PEG sind für eine Freisetzungsverbesserung von Fenofibrat mittels Schmelzextrusion geeignet. Es liegen einphasige, molekulardisperse feste Lösungen vor. Abhängig von der Trägersubstanz wird die initiale Freisetzungsrate unterschiedlich stark erhöht, ebenso die maximale Konzentration des Arzneistoffes in Lösung. Eine bis zu 12.1-fache Übersättigung wird erreicht, die aufgrund von Rekristallisationsprozessen nicht stabil ist. Der Einsatz von polymeren Mischungen reduziert die Geschwindigkeit des Konzentrationsabfalls. Die Absorption von Wasser und Relaxationseffekte vermindern die Freisetzungserhöhung mit zunehmender Lagerdauer; dieser Entwicklung kann durch eine Optimierung des Packmittels entgegengewirkt werden. Wird der ebenfalls schwer wasserlösliche Arzneistoff Oxeglitazar verwendet, so ist die initiale Freisetzungsrate der Extrudate der des reinen Arzneistoffs unterlegen, mit Ausnahme der ternären Mischung von COP, HPMC und Oxeglitazar, die einen substanzspezifischen überadditiven Effekt aufweist. PVCL-PVAc-PEG-Oxeglitazar-Extrudate bilden im Gegensatz zu den übrigen Formulierungen keine molekulardisperse feste Lösung, sondern ein amorphes Zwei-Phasen-System. Eine Veränderung während der Lagerzeit wird nicht beobachtet, vermutlich aufgrund der höheren Glasübergangstemperaturen dieser Systeme. Lediglich das Freisetzungsprofil von COP-Felodipin-Extrudaten ist verbessert. Gegenüber dem reinen Arzneistoff ist die Freisetzung der übrigen Extrudate vergleichbar (HPMC) oder verringert (PVCL-PVAc-PEG), obwohl auch hier molekulardisperse Systeme vorliegen. Von den beiden untersuchten Technologien ist lediglich die Schmelzextrusion geeignet, um feste Dispersionen mit einem verbesserten Freisetzungsverhalten herzustellen. Das Freisetzungsprofil der Extrudate kann durch den Zusatz von Polymeren mit unterschiedlichen Eigenschaften optimiert und vorhergesagt werden, wenn das Freisetzungsprofil der Einzelpolymer-Extrudate bekannt ist. Die Ergebnisse sind aufgrund von substanzspezifischen Effekten nicht von Arzneistoff auf Arzneistoff übertragbar. Nichtsdestotrotz sind die Erkenntnisse dieser Arbeit vielversprechend, da gezeigt wird, dass das Freisetzungsprofil der Extrudate leicht beeinflusst und an spezifische Anforderungen angepasst werden kann. Weitere Untersuchungen sind notwendig, um das Konzept und die Relevanz der Ergebnisse in vivo zu überprüfen.
Hot-melt extrusion with poorly soluble drugs by Jessica Albers Pdf
Hot-melt extrusion with poorly soluble drugs is a challenging method to enhance the solubility. The formation of solid dispersions, specifically of glassy solid solutions, wherein the drug is dispersed on a molecular basis in an inert carrier, leads to metastable systems that have advantageous dissolution behaviour but suffer from physical stability problems. To date, there is poor understanding of the solid state structure, the mechanism by which dissolution enhancement occurs, the stability on storage and in dissolution, and the processing to solid dosage forms. The hot-melt extrusion process is influenced by several parameters. The right coordination of these parameters is decisive for the production of solid dispersions and thus, the success in solubility enhancement. The solid state and the viscosity of the extrudates can be controlled by the temperature of the barrels. Besides the configuration of the screw and the temperature profile of the barrel, the design of the die plate represents the third important extrusion parameter. By keeping the dead storage capacity at a minimum, an early solidification and thus a blockage of the dies can be prevented. Due to shear forces evolving in the extruder barrel and the ability of the drug to dissolve in the molten carrier before reaching the melting temperature, the process temperature can be kept below the melting point of the substances. Basic butylated methacrylate copolymer is a suitable carrier to enhance the solubility of the poorly water-soluble drug celecoxib in a hot-melt extrusion process. The best solubility enhancement can be obtained by dispersing the drug in the molten carrier on a molecular basis and thus, to form glassy solid solutions. The solid state characteristics of the solid dispersion can be revealed by DSC analysis and interpretation of the corresponding glass transitions. Such systems may contain a drug load of up to 60% and are stable at increased temperature and humidity which is due to the very low water uptake of the components. Glassy solid solutions of celecoxib and basic butylated methacrylate copolymer have a fast dissolution rate and result in a 58 fold supersaturated solution. The mechanism of drug release from these glassy solid solutions is carrier-controlled and governed by dissolution. The enhancement of the dissolution rate is based on improved solubility and wettability. Basic butylated methacrylate copolymer interacts chemically with celecoxib in an acid-base reaction. The hot-melt extrusion process is highly dependent on the physicochemical properties of the compounds and their miscibility in the molten state. The use of basic butylated methacrylate copolymer as solubility enhancing carrier in hot-melt extrusion cannot be transferred easily to all drugs. Depending on the properties of the drug, specifically the melting point and the pKa, basic butylated methacrylate copolymer can be a useful carrier in glassy solid solution formation, but might be insufficient for solubility improvement. The formation of a glassy solid solution evolves from interactions between the drug and the carrier. Bonds can differ in their strength and can be advantageous or disadvantageous for a fast dissolution. Furthermore, decomposition processes can occur, when processing the drug at high temperatures. Thus, each formulation has to be analyzed separately. The interpretation of the chemical structure, the calculation of solubility parameters, the determination of melting temperatures and enthalpies, and the performance of molecular dynamics simulations are tools to predict the miscibility of drugs and carriers for the formulation of solid dispersions. A combined approach of tools predicting miscibility is highly appropriate, as no single technique may yield all the required information. Nevertheless, the evaluation of the melting behaviour via DSC has the highest impact. Hot-melt extruded glassy solid solutions can be processed into solid dosage forms. The mechanical energy input through milling and zabletting has no influence on the solid-state stability. The solution-state stability can be achieved by adding HPMC to the external phase. The filling of capsules with milled hot-melt extrudates is a promising technique to obtain solid dosage forms from glassy solid solutions. By the extensive analysis of the hot-melt extrusion process, the interactions of the compounds, the thermal characteristics, and the dissolution mechanism of the resulting systems, it is possible to predict the extrusion process in an early stage of development and to improve the dissolution of poorly soluble drugs.
Gordon Tiddy,Gordon J. T. Tiddy,Reginald B. H. Tan
Author : Gordon Tiddy,Gordon J. T. Tiddy,Reginald B. H. Tan Publisher : Royal Society of Chemistry Page : 283 pages File Size : 44,7 Mb Release : 2012 Category : Science ISBN : 9781849733786
NanoFormulation by Gordon Tiddy,Gordon J. T. Tiddy,Reginald B. H. Tan Pdf
NanoFormulation covers advances in research, development and applications of innovative formulation technologies where nanomaterials play an essential role.
