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Release Study (release + study)
Selected AbstractsHydrophobic Functional Group Initiated Helical Mesostructured Silica for Controlled Drug Release,ADVANCED FUNCTIONAL MATERIALS, Issue 23 2008Lei Zhang Abstract In this paper a novel one-step synthetic pathway that controls both functionality and morphology of functionalized periodic helical mesostructured silicas by the co-condensation of tetraethoxysilane and hydrophobic organoalkoxysilane using achiral surfactants as templates is reported. In contrast to previous methods, the hydrophobic interaction between hydrophobic functional groups and the surfactant as well as the intercalation of hydrophobic groups into the micelles are proposed to lead to the formation of helical mesostructures. This study demonstrates that hydrophobic interaction and intercalation can promote the production of long cylindrical micelles, and that the formation of helical rod-like morphology is attributed to the spiral transformation from bundles of hexagonally-arrayed and straight rod-like composite micelles due to the reduction in surface free energy. It is also revealed that small amounts of mercaptopropyltrimethoxysilane, vinyltrimethoxysilane, and phenyltrimethoxysilane can cause the formation of helical mesostructures. Furthermore, the helical mesostructured silicas are employed as drug carriers for the release study of the model drug aspirin, and the results show that the drug release rate can be controlled by the morphology and helicity of the materials. [source] Antibacterial polyvinyl chloride/antibiotic films: The effect of solvent on morphology, antibacterial activity, and release kineticsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2010Martha Merchan Abstract Medical-grade polyvinyl chloride was modified with sodium ampicillin in a concentration range from 0 to 5 wt % by solvent casting technique using cyclohexanone and N,N -dimethylformamide. The obtained polymeric systems were characterized by optical microscopy, tensile test, and scanning electron microscopy. In addition, in vitro antibacterial activity against Gram-negative and Gram-positive bacteria was determined by an agar diffusion test. Antibiotic release experiments were performed in distilled water and physiological saline solution, which were monitored by UV-vis spectroscopy. The results showed a crucial role of the solvent on the morphology, antibacterial activity, and releasing characteristic of the ampicillin. Furthermore, a mathematical model was applied to data obtained from release study, to characterize the release kinetics of the ampicillin from the polyvinyl chloride-antibiotic systems. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Preparation and in vitro evaluation of new pH-sensitive hydrogel beads for oral delivery of protein drugsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010I. M. El-Sherbiny Abstract New biodegradable pH-responsive hydrogel beads based on chemically modified chitosan and sodium alginate were prepared and characterized for the controlled release study of protein drugs in the small intestine. The ionotropic gelation reaction was carried out under mild aqueous conditions, which should be appropriate for the retention of the biological activity of an uploaded protein drug. The equilibrium swelling studies were carried out for the hydrogel beads at 37°C in simulated gastric (SGF) and simulated intestinal (SIF) fluids. Bovine serum albumin (BSA), a model for protein drugs was entrapped in the hydrogels and the in vitro drug release profiles were established at 37°C in SGF and SIF. The preliminary investigation of the hydrogel beads prepared in this study showed high entrapment efficiency (up to 97%) and promising release profiles of BSA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Chemo-Enzymatic Synthesis of Degradable PTMC- b -PECA- b -PTMC Triblock Copolymers and their Micelle Formation for pH-Dependent Controlled ReleaseMACROMOLECULAR BIOSCIENCE, Issue 6 2009Sachiko Kaihara Abstract A series of degradable triblock copolymers, poly(trimethylene carbonate)- block -poly[poly(ethylene glycol)- co -cyclic acetal]- block -poly(trimethylene carbonate) (PTMC- b -PECA- b -PTMC), were chemo-enzymatically synthesized. Cyclic acetal was introduced into a poly(ethylene glycol) segment as a degradable segment to impart a pH-dependent degradation nature and to prevent the production of acidic degradation products. Amphiphilic polymeric micelles were successfully prepared, and the properties of the micelles were significantly affected by their chemical compositions and the molecular weights. A drug release study showed that the release rate increased as the pH of the buffer decreased due to the degradation of the cyclic acetal segments, indicating its high utility for pH-sensitive controlled release. [source] Preparation, characterization and preliminary calcium release study of floating sodium alginate/dextran-based hydrogel beads: part IPOLYMER INTERNATIONAL, Issue 1 2008Sunil Kumar Bajpai Abstract Ionically crosslinked calcium alginate/dextran-based floating beads were prepared using NaHCO3 as porogen. Various micrometric properties such as tapped density, apparent density, compressibility index, etc., were determined for beads with different compositions. The beads were also evaluated for their mechanical strength. The percent buoyancy of the beads was measured as a function of time in simulated gastric fluid (pH = 1.2 at 37 °C). The beads prepared with higher concentrations of NaHCO3 porogen and CaCl2 crosslinker possessed 100% buoyancy and remained buoyant for nearly 20 h, or even more. Finally, the release of calcium from the beads was observed to follow diffusion-controlled Higuchi kinetics. Copyright © 2007 Society of Chemical Industry [source] Preparation and characterization of tetracycline-loaded interpenetrating polymer networks of carboxymethyl cellulose and poly(acrylic acid): water sorption and drug release studyPOLYMER INTERNATIONAL, Issue 10 2005Anil Kumar Bajpai Abstract Tetracycline (TC)-loaded ionic interpenetrating polymer networks (IPNs) of carboxymethyl cellulose (CMC) and crosslinked poly(acrylic acid) (PAA) were prepared and characterized by infrared spectral analysis, differential scanning calorimetry and scanning electron microscopy techniques. The prepared IPNs were evaluated for in vitro blood compatibility by clot formation and hemolysis methods and their water imbibitions capacity was determined. Fractional release dynamics of tetracycline was also investigated from loaded IPNs of CMC and PAA. The entrapped drug was examined for antibacterial activity and structural integrity and effects of various parameters such as percentage loading of the drug, chemical composition of the carrier IPN, pH and temperature of the release medium were investigated on the release profiles of TC. The drug was also released in different simulated biological fluids. Copyright © 2005 Society of Chemical Industry [source] | ||||||||||