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1
Authors: Luangtana-anan, M., Catellani, P.L., Colombo, P., Dinarvand, R., Fell, J.T., Santi, P.
تاریخ: 2012
keywords: article, binding kinetics, dispersion, energy, liquid, mathematical parameters, physical chemistry, surface tension, tablet disintegration, temperature
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[No abstract available]
2
Authors: Dinarvand, R., D'Emanuele, A.
تاریخ: 2012
keywords: article, controlled study, device, drug delivery system, drug release, environmental temperature, heat sensitivity, hydrogel, pharmaceutics, priority journal
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Two responsive delivery devices are described from which the release of molecules is dependent on the temperature of the milieu. The devices utilise thermoresponsive hydrogels which possess a lower critical solution temperature (LCST). A novel thermoresponsive device based on the use of a thermoresponsive valve is described from which significant release of molecules only occurs at temperatures above the LCST of the hydrogel. Thermoresponsive hydrogel discs were also prepared from which significant release of molecules only occurs at temperatures below the LCST of the hydrogel. It was found that the release of molecules from both devices, the thermoresponsive valve-based device and the discs, could be controlled by changing the environmental temperature. © 1995.
3
Authors: Dinarvand, R., Wood, B., D'Emanuele, A.
تاریخ: 2012
keywords: article, diffusion coefficient, hydrogel, nuclear magnetic resonance, priority journal, temperature
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[No abstract available]
4
Authors: D'Emanuele, A., Dinarvand, R.
تاریخ: 2012
keywords: article, drug release, hydrogel, particle size, pharmaceutics, polymerization, priority journal, scanning electron microscopy, temperature
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An emulsion polymerisation method for the preparation of thermoresponsive hydrogel microspheres based on N-isopropylacrylamide is described in this paper. It was found that microsphere size distribution could be altered by varying the rate of stirring during the polymerisation process and also by modifying the concentration of lecithin. Microspheres were imaged in the fully hydrated state using environmental scanning electron microscopy (ESEM). Thermoresponsive release of a model drug from the microspheres was found to be a function of microsphere size, with improved control as microsphere size increased. © 1995.
5
Authors: D'Emanuele, A., Dinarvand, R.
تاریخ: 2012
keywords: erratum, error, priority journal
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[No abstract available]
6
Authors: Dinarvand, R., Zainali, B.
تاریخ: 2012
keywords:
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[No abstract available]
7
Authors: Dinarvand, R., Zainali, B., Atyabi, F.
تاریخ: 2012
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Preparation and characterization of nifedipine microspheres using ethylcellulose as matrix polymer is described. Nifedipine microspheres were prepared by solvent evaporation technique. The influence of different parameters such as the effect of the concentration of internal and externat phases, the amount of drug and the rate of stirring of the medium on the size distribution of microspheres were studied. The effect of drug/polymer ratio and mean particle size on the drug release pattern were also evaluated. Drug release from nifedipine microspheres was studied in a medium, which simulated the change in pH of the pathway of the microspheres from stomach to intestine. It was found that with increase in the concentration of the internal phase, the size of microspheres became larger. Increasing the amount of polyvinyl alcohol in the external phase reduced the size of microspheres. Dissolution was found to be inversely related to the pH, in a way that drug release decreased at higher pH: Drug release from microspheres with small mean particle size was faster than those with large mesh particle size and followed Higuchi model of kinetics.
8
Authors: Bolourtchian, N., Nokhodchl, A., Dinarvand, R.
تاریخ: 2012
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Physical characteristics of carbamazepine crystals grown from pure ethanol or acetone under different conditions were studied for the morphology of crystals by scanning electron microscope, x-ray powder diffraction and FT-IR, and for thermodynamic properties by differential scanning calorimeter. Also the dissolution behavior and compaction properties of crystals were studied. The results showed that crystallization of carbamazepine using watering-out method produced needle shape crystals while by the other methods such as reducing temperature or solvent evaporation produced polyhedral crystals in alcohol and thin plate-like crystals in acetone. The crystals which were grown from acetone were larger than those from alcohol. Differential scanning calorimetery and x-ray powder diffraction showed no evidence of polymorphism for carbamazepine crystallized by reducing the temperature or by the solvent evaporation in contrast with the crystals produced by the watering out technique. Crystallization of carbamazepine by different methods especially watering-out technique improved its dissolution rate and compatibility and produced high crushing strength compacts without capping.
9
Authors: Dinarvand, R., Mirfattahi, S., Atyabi, F.
تاریخ: 2012
keywords: article, concentration (parameters), controlled study, drug analysis, drug formulation, drug release, drug synthesis, electron microscopy, emulsion, human, morphology, particle size, prediction, scanning electron microscopy, surface property, technique
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Microspheres of isosorbide dinitrate (ISDN) were prepared using the emulsification/solvent evaporation method. The impacts of different factors such as stirring rate, concentration of ethyl cellulose (EC) as matrix polymer, poly vinyl chloride (PVA) as stabiliser and ISDN on the characteristics of the microspheres were investigated. The morphology of microspheres was studied using optical and scanning electron microscopy and it was shown that microspheres had a spherical shape and smooth surface. The particle size distribution of microspheres, analysed by a sieving method, was affected by stirring rate and concentrations of EC, PVA and ISDN. Larger microspheres showed greater drug loading and smaller microspheres showed a faster drug release. The in vitro drug release from microspheres was predictable and reproducible, conforming to the Higuchi model of release kinetics.
10
Authors: Atyabi, F., Koochak, M., Dinarvand, R.
تاریخ: 2012
keywords: acidity, article, complex formation, controlled drug release, drug solubility, intestine fluid, ionic strength, pH measurement, simulation, stomach juice
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Drugs can be loaded on ion exchange resins in order to control their release Loading of diclofenac sodium on the resin beads not only sustain its release but also reduce its gastrointestinal mucosal injury. In this study the effect of loading solution and concentration of diclofenac in loading solution on total amount of drug loaded on the resin beads (Amberlite IRA-900) and the release characteristic of drug in different media were examined. Results showed that diclofenac resin complex did not release their drug content in simulated gastric fluid but released it in simulated intestinal fluid independent of exposure time in acidic conditions. The effect of a number of parameters such as ionic strength and pH on the release characteristc of drug-resin complexes were also examined. Results showed that although ionic strength is an important factor, drug release is more affected by the pH of the media.

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