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Controlled Drug Delivery (controlled + drug_delivery)
Selected AbstractsMagnetically Triggered Reversible Controlled Drug Delivery from Microfabricated Polymeric Multireservoir DevicesADVANCED MATERIALS, Issue 40 2009Kaiyong Cai The pulsed reversible release of dual drugs from biodegradable polymeric multireservoir devices is successfully demonstrated. The controlled release is achieved by incorporating magnetic particles in the devices as switch carriers. It is possible to intentionally switch on/off the drug release at any desired time for a chosen duration. [source] Preparation and characterization of interpenetration polymer network films based on poly(vinyl alcohol) and poly(acrylic acid) for drug deliveryJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008Yu-Mei Yue Abstract A series of full interpenetrating polymer network (full-IPN) films of poly(acrylic acid) (PAA)/poly (vinyl alcohol) (PVA) were prepared by radical solution polymerization and sequential IPN technology. Attenuated total reflectance-Fourier transform infrared spectroscopy, swelling properties, mechanical properties, morphology, and glass transition temperature of the films were investigated. FTIR spectra analysis showed that new interaction hydrogen bonds between PVA and PAA were formed. Swelling property of the films in distilled water and different pH buffer solution was studied. Swelling ratio increased with increasing PAA content of IPN films in all media, and swelling ratio decreased with increasing PVA crosslink degree. Tensile strength and elongation at break related not only to the constitution of IPNs but also to the swelling ratio of IPNs. Mechanical property of glutaraldehyde (0.5%) for poly(vinyl alcohol) crosslinking was better than that of glutaraldehyde (1.0%). DSC of the IPN films showed only a single glass transition temperature (Tg) for each sample, and Tg data showed a linear relationship with network composition. Morphology was observed a homogeneous structure, indicating the good compatibility and miscibility between PAA and PVA. Potential application of the IPN films in controlled drug delivery was also examined using crystal violet as a model drug. The release rate of the drug was higher at 37°C than 25°C for all IPNs and also increased slightly with decreasing of poly(acrylic acid) content. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Self-assembly of drug,polymer complexes: A spontaneous nanoencapsulation process monitored by atomic force microscopy,JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 1 2003Mireia Oliva Abstract Since hydrophilic matrices were proposed for controlled drug delivery, many polymeric excipients have been studied to make drug release fit the desired profiles. It has been pointed out that ,-carrageenan, a sulfated polymer from algae, can suitably control the release rate of basic drugs from hydrophilic matrices. Furthermore, the relevance of hydrophobic interactions in drug,polymer aqueous systems has already been demonstrated, although no references to morphological features as well as to the kinetics of the interaction complexes formation have been published to date. In this work, we propose a method to monitor the topographical evolution of the interaction between ,-carrageenan and dexchlorpheniramine maleate, in order to determine how the release profiles can be so easily controlled. For this purpose, solutions of both polymer and drug were prepared at very low concentration. Solutions were mixed and small volumes were taken every hour for over a period of 24 h and subsequently analyzed. The characterization technique used, atomic force microscopy, provides a high resolution, allowing plotting of three-dimensional images of the sample morphology within the nanometric scale. The results demonstrate that ,-carrageenan is able to nanoencapsulate spontaneously dexchlorpheniramine maleate molecules, which offers the possibility of controlling the release rate of the drug with no need of complex technological processes. Moreover, this work demonstrates the suitability of atomic force microscopy for the specific case of the on-time monitoring of interaction processes that occur in pharmaceutical systems. © 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 92:77,83, 2003 [source] Preparation and characterization of a customized cellulose acetate butyrate dispersion for controlled drug deliveryJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 6 2002Siva Vaithiyalingam Abstract The purpose of the present experiment was to prepare and characterize the aqueous-based pseudolatex system of cellulose acetate butyrate (CAB) for controlled drug delivery. Aqueous pseudolatex systems are advantageous over organic-based coating systems because these systems are devoid of criteria pollutants such as carbon monoxide, nitrogen oxides, nonmethane volatile organic compounds, and sulfur dioxide. Pseudolatex was prepared with CAB and polyvinyl alcohol (stabilizer) by a polymer emulsification technique. The stability of pseudolatex was evaluated. Particle size was measured and rheological experiments were conducted. The glass transition temperature, microscopic free volume, permeation coefficient, and mechanical properties of plasticized pseudolatex films were estimated. Surface roughness of coating on inert Nu-Pareil® beads (Ingredient Technology Corp., Mahwah, NJ) was measured as a function of coating weight gain. The CAB Pseudolatex was found to be stabilized by steric forces. From intrinsic viscosity, the thickness of the stabilization layer was estimated. An increase in polymeric particles proportionately decreased the thickness of the stabilization layer. All the essential properties of a coating membrane such as microscopic free-volume fraction, permeability coefficient, mechanical properties, and glass transition temperature were fairly controllable as a function of plasticizer concentration. The pseudolatex dispersion of CAB was stable with negligible sedimentation volume and a particle size of 300 nm. Because CAB is water insoluble and non-ionizable, this pseudolatex can be used for pH-independent coating. The films obtained were strong and flexible for controlled drug delivery applications. Coating with the CAB dispersion reduced the surface roughness of beads but it remained stable as a function of increase in coating weight gain. © 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91:1512,1522, 2002 [source] From thermoplastic elastomers to designed biomaterialsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 14 2005Joseph P. Kennedy Abstract This highlight is about my metamorphosis from a cationic polymerization chemist to a biomaterialist (no pun intended) and some of the main events on the road. My earlier career faded away with the discovery of living cationic polymerizations, chronicled in my 1999 highlight, but it also put me on the road to designed biomaterials. My new career started with, and still focuses on, the creation of new polymeric architectures, mainly by cationic techniques, for toughened bone cements, injectable intervertebral discs, nonclogging artificial blood vessels, and amphiphilic networks for controlled drug delivery and immunoisolatory membranes. The enormous complexities of immunoisolation of pancreatic islets are now center stage, and lately we have been using all kinds of techniques to make unique membranes to correct type 1 diabetes. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2951,2963, 2005 [source] Encapsulation and Controlled Release of a Hydrophobic Drug Using a Novel Nanoparticle-Forming Hyperbranched Polyester,MACROMOLECULAR BIOSCIENCE, Issue 7 2005Jianhua Zou Abstract Summary: An amphiphilic, hyperbranched polymer suitable for use in controlled drug delivery is reported. This polymer was obtained by modification of the hyperbranched aliphatic polyester BoltornÔ H20 (H20) with succinic anhydride and then glycidyl methacrylate, and formed nanoparticles in aqueous solution. The critical association concentration was 7.4,×,10,3 g,·,L,1, as determined by fluorescence spectroscopy using pyrene as a molecular probe. A static/dynamic laser light scattering (LLS) study revealed that the average particle size was 39.4 nm with a low particle size distribution (PDI = 0.04), and that each particle was composed of about 350 amphiphilic molecules. Daidzein, a hydrophobic traditional Chinese medicine, was encapsulated during particle formation and the release properties were determined. The optimal feeding concentration of daidzein to hyperbranched polyester was 4.9,×,10,5 g,·,mL,1 to 5.0,×,10,3 g,·,mL,1 with a loading efficiency of 76.1%. In the presence of the enzyme Lipase PS, the drug loaded nanoparticles degraded in a random one-by-one manner and released the drug over a few days. This system is therefore a novel controlled drug release system based on nanoparticles formed of hyperbranched polyester. Encapsulation of daidzein by hyperbranched polyester particles. [source] High-pressure NMR characterization of triacetyl-,-cyclodextrin in supercritical carbon dioxideMAGNETIC RESONANCE IN CHEMISTRY, Issue 2 2009G. I. Ivanova Abstract Cyclodextrins are used in many drug formulations since their cavities provide microenvironments where drug molecules can enter and form inclusion complexes for controlled drug delivery. Supercritical carbon dioxide (scCO2) is an alternative to organic solvents and a very attractive medium for the preparation of these inclusion complexes. The potential ability of triacetyl-,-cyclodextrin (TA-,-CD) to form inclusion complexes in addition to its high miscibility in liquid and scCO2 could offer a chance for an economical and environmental friendly chemical processing. In this work, high-pressure NMR studies were performed in order to obtain information on the molecular structure and dynamics of TA-,-CD in scCO2 at 313.15 K and 20 MPa and its ability to form inclusion complexes under these conditions was studied. The influence of scCO2 on a number of NMR spectral parameters, such as chemical shifts, spin-spin coupling constants, nuclear Overhauser effect (NOE) and spin-lattice relaxation (T1) has been studied. We unequivocally show for the first time structural changes of TA-,-CD in scCO2, like acetyl chain orientation and overall shape distortions that can affect its inclusion capability in this medium. The possibility of cavity self-closure is discussed and the results of two inclusion studies that support cavity self-closure, with the angiotensin-converting enzyme inhibitor, captopril, and the nonsteroid anti-inflammatory drug, flufenamic acid, are presented. Copyright © 2008 John Wiley & Sons, Ltd. [source] | |||||||||||||