1,720,998 research outputs found
New Controlled-Release Ibuprofen Tablets
No full textTablets containing two different doses of ibuprofen are realized. The first possesses very fast release kinetics, while the second has slow and linear release kinetics. This allows drug to produce a therapeutic effect quickly and to maintain it for a long time with only one administration unit. Such tablets are obtained by compression of a mixture of two very different kinds of granulates: an ibuprofen-starch granulate and an ibuprofen–Eudragit RS microsphere granulate. Specific proportions of mixtures of them give the described result after compression at particular tablet hardnesses
Interactions between Lonidamine and b- or hydroxypropyl -b- cyclodextrin
No full textThe possibility of obtaining inclusion complexes between lonidamine and β- or hydroxypropyl-β-cyclodextrin have been evaluated by phase solubility diagram, differential scanning calorimetry (DSC), and x-ray diffractometry. The applied complexation methods were spray-drying, kneading, and solid dispersion. DSC and x-ray analyses of the powders revealed an external interaction between lonidamine and cyclodextrins. Dissolution profiles of the obtained powders were also studied to define the most appropriate preparation method and molar ratio to use in attempts to increase lonidamine water solubility
Drug release from compressed Eudragit RS 30D coated beads
No full textTablets of different hardnesses and compositions were prepared with an original theophylline granulate previously coated with Eudragit RS 30D. Dissolution studies of each tablet formulation were performed to verify any kinetic variationfrom the dissolution profile. This was obtained by filling with the same coated granules in a hard gelatine capsule. While the dissolution profiles of the capsules possesses very good linearity, the tablet kinetics gradually deviate from this linearity with an increase in the percentage of the coated granules in the formulation. Tablet hardness has only a marginal influence on this kinetic deviation
Characterization and dissolution studies of PEG 4000/fenofibrate solid dispersions
No full textSolid dispersions of fenofibrate in PEG 4000 were prepared by the solvent and fusion methods. The binary systems are successively studied and characterized using differential scanning calorimetry. X-ray diffractometry and Fourie transform infrared spectroscopy. Dissolution studies of the solid dispersed powders were performed to verify the water solubility improvement of the fenofibrate present in the formulations
Rheological, mucoadhesive and release properties of carbopol gels in hydrophilic cosolvents
No full textCarbopol is one of the most common thickening agent for water phases. It is used after neutralisation and its rheological
properties in the aqueous medium are well known. The aim of this work was to investigate the gelation properties of Carbopol
971 e 974 polymeric systems in water-miscible cosolvents such as glycerine and PEG 400. Since in these cosolvents, carboxypolymethylene
precipitates after neutralisation with a base, then the attention was pointed out of the gelation properties of the
different systems at increasing temperature, in order to obtain Carbopols gels avoiding neutralisation and, at the same time,
making possible the dissolution in these gels of insoluble or poorly soluble water drugs. Rheological properties of PEG 400
and glycerine samples were compared with similar systems in water by performing oscillatory analyses and measuring the main
rheological parameters, G, G and δ. The results obtained showed that Carbopol 971 and 974 in PEG 400 gave rise after heating
to gels that show a satisfactory rheological behaviour. The elastic modulus is greater than the viscous one showing a remarkable
elastic character of these samples and the performed frequency sweeps show a typical spectrum of a “gel-like” structure. Being
Carbopols well-known mucoadhesive polymers, gels adhesive properties were studied using the ex vivo method. Then, the
possible cutaneous irritation were also tested using the in vivo method (Draize test). No signs of cutaneous irritation and good
mucoadhesive properties were obtained for the PEG 400 and water gels of Carbopol 974 prepared by heating.
After rheological and mucoadhesive properties were set, paracetamol as a model drug was then inserted in the composition of
the gels and the release characteristics were defined. Dissolution tests pointed out the greater release control properties of PEG
400-Carbopol 971 samples. These studies showed PEG 400-Carbopol systems as a first-rate alternative to traditional water gels
Inclusion complexation of Fenofibrate with beta-cyclodextrin and hydroxypropyl beta-cyclodextrin. Evaluation of interactions in solution and solid complex characterization
No full textInteractions between b-cyclodextrin or hydroxypropyl b-cyclodextrin, as well as the possibility of obtaining inclusion complexes, were evaluated by several methods: a phase solubility diagram, high-power liquid chromatography, differential scanning calorimetry and X-ray diffractometry. Solid inclusion complexes were prepared by spray-drying, kneading and solid dispersion. The dissolution profiles of the obtained powders were studied in order to define the most appropriate cyclodextrin, preparation method and molar ratio to use in the production of a fenofibrate inclusion complex. Finally, tablets were prepared with the powder of the complex and characterized by dissolution studies
Rheological, mucoadhesive and release properties of carbopol gels in hydrophilic cosolvents
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Emulsion/solvent evaporation as an alternative technique in pellets preparation
No full textParacetamol/Eudragit RS, paracetamol/ethylcellulose, and paracetamol/cellulose acetate pellets of different drug/polymer ratios (w/w) were prepared by the dissolution/solvent evaporation technique. These pellets were then characterized by particle size distribution analysis, ultraviolet (UV) spectroscopy, differential thermal analysis, and scanning electron microscopy (SEM). Hard gelatin capsules were filled with each particle size fraction of these pellets, and in vitro dissolution studies were performed to verify the capability of each series of pellets to control drug release. Pellets were spherical, presented a polynucleated microcapsule structure, and under certain experimental conditions, the yield of the preparation process reached very high values. The dissolution studies pointed out the slow paracetamol release from these pellets
Methoxybutropate microencapsulation by gelatin-acacia complex coacervation
No full textMicrocapsules of methoxybutropate solid particles or of an oily saturated solution of the same drug were prepared by complex coacervation between gelatin and acacia and dried with three different methods: isopropanol addition, spray-drying, and freeze-drying. Successively, microparticles were analyzed by infrared thermobalance, ultraviolet (UV) spectroscopy, optical and scanning electron microscopy, and sieves to find out parameters such as yield, moisture content, encapsulation percentage, morphology of solid particles, and particle size. Results highlighted that the most appropriate drying method for industrial purposes was spray-drying, particularly for oil-containing microcapsule formulations.
Read More: http://informahealthcare.com/doi/abs/10.1081/DDC-10010218
Spray-drying as a method for microparticulate controlled release systems preparation: advantages and limits. I. Water soluble drugs
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