298 research outputs found
Dextran and its potential use as tablet excipient
No full textDextrans are a class of carbohydrate polymers extensively applied in pharmaceutical applications, particularly as drug conjugate macromolecular carriers or drug delivery systems. These polysaccharides improve the stability of the therapeutics enabling also the control of their release, via either the parenteral and or oral routes. In the latter case, due to their gel forming ability they may have potential as hydrophilic matrix tablets for sustained drug release.
In this paper, we investigated the behaviour of different molecular weight (1, 40, 500 and 2300 kDa) dextrans as tabletting excipients. Powder particle size and hygroscopic studies have been reported, together with tabletability, tablet stability and tablet swelling. Moreover we use tramadol as model compound to evaluate the ability of dextrans to control drug dissolution. The results suggest that dextrans with lower molecular weights may be a promising excipient to be used as filler for immediate release tablets, due to their good tabletability and fast dissolution rate, while dextrans with higher molecular weights could be an efficient disintegrant due to their swelling ability
Evaluation of Ethylcellulose-Coated pellets Optimized using the Approach of Taguchi
No full textSpherical granules of theophylline with microcrystalline cellulose and lactose were prepared in a high-speed granulator. An original experimental design based on the philosophy of Taguchi was applied to optimize the yield of the produced granules. Successively, the optimized pellets were coated with an ethylcellulose pseudolatex preparation (Surelease®) in a fluid bed coating machine using a bottom spray noule and a Wurster® column. Finally, these granules were c ompressed into tablets of different hardnesses. The chosen statistical approach proved efficient not only to find the optimal operating conditions for granulation but it also appeared to define the characteristics of a process that was robust and no sensitive to noise factors. Dissolution studies revealed a zero-order release of theophylline from the coated granules, but after the compression step, the ethyl cellulose film was damaged and the drug release was immediate
Acrylic Polymers as thickening agents for tetraglycol cosolvent
No full textThis article evaluated the thickening properties of two different Eudragits, L and RS, in tetraglycol cosolvent in order to obtain high viscosity systems characterized by controlled release properties. Tetraglycol was chosen for its ability to dissolve a wide range of water insoluble drugs, while Eudragit RS and L for their specific dissolution and permeability properties under physiological conditions. Study of the rheological properties was performed to characterize elastic and viscous properties of Eudragit/tetraglycol samples in function of frequency and temperature. For all systems, the results outlined a liquid like behavior, as observed for dilute polymer solutions. In fact the fitting of the log G′-log G′′ versus frequency curves showed a good agreement with the Rouse or Zimm models. So despite the increase in viscosity, samples still behaved like liquid systems. After the addition of paracetamol the release characteristics were defined pointing out the great release control properties of both Eudragit L and RS, which showed different release kinetics depending on the pH of the environment. Semisolid Eudragits/tetraglycol systems can be considered as a new alterative for the sustained release of insoluble or poorly water-soluble drugs
Evaluation of spray-drying as a method to prepare microparticles for controlled drug release
No full textThe possibility to obtain microcapsules or microspheres for controlled release by spray-drying is evaluated. Drugs of different solubilities like theophylline and sodium sulfamethazine, with Eudragit RS as coating polymer, are chosen.
The polymer is used, either dissolved in an hydroalcoholic solution or suspended (pseudolatex) in water, in different weight ratios with the drug. The obtained solution or suspension is spray-dried.
Scanning electron microscope analysis of the powders reveals no sign of microencapsulation. Moreover, only a fraction of the particles has a spherical shape.
For each spray-dried powder, a part of the obtained particles is compressed into tablets, and the rest is stored.
Dissolution studies in distilled water at 37 C are performed on powders and tablets.
While the uncompressed microparticles do not give any controlled release, the tablets show an ability in slowing down drug delivery greater than the one obtained with the traditional methods
Inclusione del metossibutropato in ß- ed idrossipropil ß-ciclodestrine: diverse metodiche di preparazione a confronto
No full textNon disponibil
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
The Taguchi's performance statistic to optimize Theophylline beads production in a high-speed granulator.
No full textAn original process using a simple procedure is developed to produce theophylline active pellets. In order to improve this process, an optimization approach is applied. But rather than only trying to bring the process to the target optimal values, attempt is made to find operating conditions leading also to stable and non-sensitive pellets characteristics. In this purpose, the classic experimental design approach and response surface methodology are completed by using Taguchi's philosophy
Coacervazione complessa gelatina-gomma arabica quale metodo di microincapsulazione del ketoprofene
No full textNon disponibil
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
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