Polymers are defined by patterns of repeating chemical structures called monomers. They are among the common constituents of both living and non-living matters on the planet. Perhaps, polymers are major inputs in pharmaceutical formulations and also in the new frontiers of nano-based drug/vaccine delivery systems. Most natural polymers, as such, are not however suitable for a number of applications unless their properties are tailored and tamed via certain modifications. Such modifications of polymers as part of developing robust pharmaceutical excipients have also traditionally targeted to reduce their noxious properties and annihilate in vivo toxicities. The book explored the fundamental aspects of starch-based polymeric cross-linking using food grade cross-linking agent. The cross-linked starch microparticles which were physico-chemically characterized and loaded with model drug demonstrated impressive drug-release-sustaining capability. Readers in the Pharmaceutical industry and researchers in the academia and specialized laboratories working on design and development of drug delivery systems are the main beneficieries of the this book.
Mucoadhisive microcapsules are proposed for the antidiabetic drug glipizide, to obtain controlled release. Glipizide microcapsules with a coat consisting of pectin was prepared by employing ionic gelation process and emulsification ionotropic gelation process. The microcapsules were evaluated for flow properties, Carr’s index, hausner ratio, micro encapsulation efficiency, drug release characteristics, surface characteristics; compatibility studies mucoadhesive properties. Pectin is a polysaccharide with a variable molecular weight. In the presence of calcium ions, pectin forms a gel of calcium pectinatethat are more resistant to disruption in the gut than alginate gel. Researchers have formulated oral controlled release products of glipizide by various techniques. Dosage forms that are retained in the stomach would increase the absorption, improve drug efficiency and decrease dose requirements. Thus, an attempt is made in the present investigation to use chitosan as a mucoadhesive polymer and prepare microspheres. The microspheres will be characterized by in-vitro and iv-vivo tests and factorial design will be employed to optimize the variables.
Microspheres is a novel drug delivery system which involves entrapment of a drug moiety in a polymeric membrane to alter the release profile of the drug. The present book provides a guide on development and evaluation methodology for microspheres for anticancer drug. Ethyl cellulose microsphere for anticancer drug 5-Flurouracil is selected as a model example. 5-FU is an antimetabolite and immunosuppressive agent. It is used in the treatment of breast, colon, stomach, pancreas, ovary, urinary bladder and lung cancers. But it has a rapid plasma clearance and a short half-life. The drug can be encapsulated in microspheres to prolong its residence time and thereby its action. The ethyl cellulose microspheres containing 5-FU were prepared by a w/o/w emulsification solvent evaporation technique. The process variables in the preparation of 5- FU loaded ethyl-cellulose microspheres were optimized.A factorial design was employed to evaluate the effect of the selected independent variables on some in-vitro attributes of microspheres. Accelerated stability studies of 5- FU loaded ethyl cellulose microspheres was performed.
Microparticles are one of the key novel drug delivery systems has been widely used to precisely modulate release rate. Microparticles based polymeric systems fabricated using suitable carrier has been extensively explored as an effective matrix for controlled and sustained release delivery of many drugs. With the controlled release systems, the rate of drug release matches the rate of drug elimination, and therefore the drug concentration is within the therapeutic window for the majority of the 24-hr period.The aim of this study was to prepare Eudragit microspheres containing Tramadol HCl by solvent evaporation method to achieve a controlled drug release profile. Investigation of the effect of various processing and formulation factors such as polymer type, drug: polymer ratio, stirring speed to obtain spherical particles. Then yield of production, shape, and mean particle size, particle size distribution, encapsulation efficiency, surface properties and release rate of drug from the microspheres were performed.
Microspheres made from lipids and polymers provide an interesting opportunity for use as drug delivery vehicles for numerous therapeutics that can range in size from small molecules to macromolecules like peptide/protein. In addition, cationization on the lipid-based microsphere systems has tremendous application for drug absorption enhancement and for ‘ferrying’ compounds across cell membranes. Surely excipients play an important role not only to make an acceptable microsphere product but also to minimize/prevent the degradation of the incorporated drug molecules. Special emphasis is being given particularly on various instability problems and investigated mechanistic ways to obviate the possible instability problems of peptide/protein drug during microsphere preparation as well as its release from the microspheres. This book surveys a comprehensive list of published examples of excipients relevant to currently or previously marketed drugs. With this coverage, this book enlists a myriad of excipients available for the formulation scientist to design the lipidic and polymeric microspheres.
Microsphere carrier systems made from the biodegradable polymers have attracted considerable attention for several years in sustained drug delivery. However, the short residence time at the site of absorption could be overcome by coupling bioadhesion characteristics to microspheres and developing bioadhesive microspheres with the help of bioadhesive polymers. Neostigmine Bromide – a cholinesterase inhibitor is widely used for the treatment of Myasthenia Gravis. It is presently marketed in conventional dosage form as a tablet in usual strength of 15-30 mg for peroral route. Extent of absorption of drug through oral route is only 1-2% of 30 mg of administered dose. Hence there is need of novel nasal drug delivery system for the treatment of Myasthenia Gravis. To overcome inherent drawbacks associated with conventional dosage forms of Neostigmine Bromide, an attempt is being made in the present research work to develop an alternative drug delivery system in the form of Nasal mucoadhesive microspheres to increase the rate and extent of absorption and to reduce the dosing frequency of the formulation.
This book initially provides a review of floating drug delivery systems. This system has a bulk density lower than the gastric content. They remain buoyant in the stomach for a prolonged period of time, with the potential for continuous release of drug. Gastric emptying is much more rapid in the fasting state and floating systems really heavily on the presence of food to retard emptying and provide sufficient liquid for effective buoyancy. When microspheres come in contact with gastric fluid the gel formers, polysaccharides, and polymers hydrate to form a colloidal gel barrier that controls the rate of fluid penetration into the device and consequent drug release. The air trapped by the swollen polymer lowers the density and confers buoyancy to the microspheres. However a minimal gastric content needed to allow proper achievement of buoyancy. Hollow microspheres of Acrylic resins 57, Eudragit, PMAA, floating granules are the recent developments in this field. The book then presents studies conducted on producing microspheres containing Antidiabetic drug. The book also discusses various formulation and processing parameters and in-vivo study in wistar rats.
In the recent years considerable attention has been focused on the development of new drug delivery systems. Recently, several new techniques for drug delivery are made which are capable of controlling the rate of drug delivery, sustaining the duration of therapeutic activity or targeting the delivery of the drug to a tissue. A basic concept in ophthalmic research and development is that the therapeutic efficacy of an ophthalmic drug can be greatly improved by prolonging its contact with the corneal surface. Ocular drugs and delivery systems are currently undergoing a process of design optimization due to inherent physiological and anatomical constraint of the eye leading to limited absorption of topically applied drugs. Eye being a most delicate organ, ocular drug delivery is a challenge for the formulator. Novel trend in ocular research is to formulate a dosage form which not only prolongs the residence of system in eye but also helps to reduce the elimination of the drug and side effects. This book describes design, development and evaluation of such novel vesicular system for sustained ocular delivery of antiglaucoma drug.
The present study deals with the design, development and evaluation of microspheres of an antidiabetic drug by using different polymers for entrapping the drug to give controlled release, minimize frequent dosing thus improving patient compliance. Two different methods were used for preparing the different formulation of microspheres viz. ionotropic gelation method and non-aqueous solvent evaporation method.
The present study was an attempt to develop microspheres for diltiazem HCl using three different polymers. Diltiazem HCl, being a hydrophilic drug was entrapped in the microspheres by w/o solvent evaporation method. To optimize the weight of polymer, totally five batches were prepared for each of the polymer and various evaluation parameters were studied. The ratio 1:2 (i.e. formulation ERS4) shows highest production yield, drug content and percentage entrapment among the all formulations. FTIR and XRD analysis was also carried out for pure drug and drug containing ethylcellulose, eudragit RS 100 and eudragit RL 100 microspheres, which shows there were no drug-polymer interaction. Based on these test, ERS4 was chosen as the best formulation. Then for all the formulations, in vitro release study was carried out for eight hrs. Which shows the formulation ERS4 and ERS5 having much prolonged release compare to remaining formulations. Dissolution data were fitted to different mathematical models, which follows the diffusion controlled release mechanism from all prepared batches.
Herbal formulation is one of the novel drug delivery systems which possesses various advantages, including increasing drug solubility, enhancing dissolution rate, bioavailability, etc. Piper betle leaves Linn. (Family: Piperaceae) have been used in Chinese and Indian folk medicine for centuries, and recently been proposed to be used as a chemoprevention agent because of its anti-oxidant activity. The cytotoxicity of the aqueous extract of PBL was carried out to find its anticancer properties. A 3-level full factorial design was employed to optimize the process conditions for formulating spherical shaped microspheres with higher encapsulation of drug. Formulation A1 to A9, B1 to B9 and C1 to C9 were prepared using three independent variables (drug-polymer ratio and stirring speed) and evaluated for dependent variables (shape, percentage yield, particle size, percentage drug loading and percentage cumulative release of drug in 24 h). The cytotoxicity studies on Hep-2 cell line of sodium alginate microspheres exhibited a mean CTC50 of 95.20 µg/ml. In case of BSA and chitosan microspheres this was found to be 90.00 and 94.00 µg/ml respectively.
The text book entitled “MATRIX TABLETS: AN APPROACH TOWARDS SUSTAINED RELEASE DRUG DELIVERY” emphasizes on the general introduction, approaches to sustained release drug delivery system, matrix tablets, method of preparation, drug release mechanism, evaluation of SRDDS and packaging of matrix tablets. An attempt has been made to cover various marketed preparation and patents related to of sustained release matrix tablets. The book may be beneficial for the pharmacy professional, students and research scholars for thorough knowledge, basics and updatation in the area till date.
Gastric Emptying is a complex process,which is highly variable and makes in-vivo performance of the drug delivery systems uncertain. In order to avoid this variability,efforts have been made to increase the retention time of the drug delivery systems for more than 12 hours. The floating or gastroretentive controlled drug delivery systems are useful in such applications. The present work adresses the physiology of the gastric emptying process with respect to gastroretentive drug delivery systems.
A Microsponge delivery system (MDS) is “Patented, highly cross-linked, porous, polymeric microspheres polymeric system consisting of porous microspheres that can entrap wide range of actives. It is a unique technology for the controlled release consists of micro porous beads, typically 10-25 microns in diameter, loaded with active agent. Aceclofenac belongs to a group of medicines called non-steroidal anti-inflammatory drugs (NSAIDs). It works by blocking the action of cyclooxygenase. The pharmacokinetic profile and intracellular metabolism of Aceclofenac provide a strong rationale for the development of a sustained release formulation. A Microsponge based drug delivery system of Aceclofenac was planned for development and characterization for in vitro performances. The effect of Eudragit RS100 and PVA on formulation of microsponges was determined by using 32 factorial design. Aceclofenac Microsponge were prepared using an Quasi emulsion solvent diffusion method by adding an organic internal phase containing Aceclofenac, Eudragit RS100, Tri ethyl citrate and solvent into a stirred aqueous phase containing polyvinyl alcohol.
The mucoadhesive drug delivery system has received great deal of attention over the past few decades. The major advantages of this system are to prolong the drug residence at a specific site of delivery and solve bioavailability problems. The major focus of this book is to explain the current research tools for designing of mucoadhesive microparticles of rabeprazole sodium and tolterodine tartrate by non-aqueous solvent evaporation technique using ethylcellulose and selected mucoadhesive polymers. The prepared microparticles of the above drugs were characterized for particle size, drug content, swelling index, mucoadhesive strength etc. In-vitro drug release study for both drugs suggested that formulation containing tolterodine tartrate with ethylcellulose based chitosan and rabeprazole sodium with ethylcellulose based HPMC K100M showed consistent drug release up to 24h. Accelerated stability study of optimized formulations such as F4 and F6c up to 6 and 3 months respectively.