Sustained release from inert matrices I. Effect of macrocrystalline cellulose on aminophylline and theophylline release

Said, S. A.; Al-Shora, H. I.

doi:10.1016/0378-5173(80)90025-3

Cited by 12 publications

(3 citation statements)

References 6 publications

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“…However, the release kinetics was found to be greatly dependent on the compaction properties of the polymer-drug granules. [6][7][8][9] Other alternatives include the design of matrix drug delivery systems in which the drug particles are dispersed in a melted polymeric phase. A common example is the compression of drug-filled polymeric compounds above the melting point of the polymer to form a solid part containing the drug.…”

Section: Introductionmentioning

confidence: 99%

“…The most conventional way to make matrix drug delivery systems is based on the compression of polymer−drug mixtures into a compact form (e.g., slabs and tablets). − Alternatively, the drugs can be previously granulated with the polymer so that the drug particles are covered with a layer aiming at retarding the respective release process. , In other studies, drugs have also been incorporated into the polymer granulates using techniques such as (i) solvent evaporation, (ii) polymer solution granulation, (iii) melt granulation, and (iv) sintering . The obtained granulates were then compressed into slabs or tablets.…”

Section: Introductionmentioning

confidence: 99%

“…The obtained granulates were then compressed into slabs or tablets. However, the release kinetics was found to be greatly dependent on the compaction properties of the polymer−drug granules. − Other alternatives include the design of matrix drug delivery systems in which the drug particles are dispersed in a melted polymeric phase. A common example is the compression of drug-filled polymeric compounds above the melting point of the polymer to form a solid part containing the drug. − In this type of device, the release kinetics is controlled by the polymer bulk properties and not by the porosity of the system.…”

Section: Introductionmentioning

confidence: 99%

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Soy Matrix Drug Delivery Systems Obtained by Melt-Processing Techniques

et al. 2003

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The aim of this study was to develop new soy protein drug delivery matrix systems by melt-processing techniques, namely, extrusion and injection moulding. The soy matrix systems with an encapsulated drug (theophylline, TH) were previously compounded by extrusion performed at two different pH values, (i) pH 4 (SIpDtp) and (ii) pH 7 (SIDtp), and further injection-moulded into a desired shape. During the extrusion process the matrixes SIDtp were also cross-linked with glyoxal (0.6X-SIDtp) and reinforced with a bioactive filler, hydroxylapatite (SI-HADtp). The obtained mouldings were used to study the drug-release mechanisms from the plastic soy-TH matrixes. In an isotonic saline solution (ISS) buffered at pH 5.0 (200 mM acetate buffer), the resulting release kinetics could be described using the Fick's second law of diffusion. Because the diffusion coefficients were found to be constant and the boundary conditions to be stationary, these systems are drug-diffusion controlled. Conversely, the dominant phenomena in an isotonic saline solution buffered at pH 7.4 (200 mM Tris/HCl buffer) are more complex. In fact, because of the higher polymer solubility, the resulting matrix is time-variant. So, the drug release is affected by swelling, drug diffusion, and polymer dissolution, being faster when compared to ISS-200 mM acetate buffer, pH 5.0. The changes in the formulation composition affecting the correspondent release rates were also investigated. At pH 7.4, increasing the cross-linking degree of the polymer matrix (via reaction with glyoxal or heat treatment) or decreasing the net charge (extruding at pH near its isoelectric point) led to lower release rates. The incorporation of ceramic filler caused the opposite effect. Because of the low solubility of the matrix at pH 5.0, no significant variations were detected with variations in the selected formulations. These systems, based on a nonstandard protein-based material, seem to be very promising to be used as carriers for drug delivery.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Soy Matrix Drug Delivery Systems Obtained by Melt-Processing Techniques

et al. 2003

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Molecular and supramolecular interactions in systems based on microcrystalline cellulose and trichlorophene

et al. 2005

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It is shown that the interaction between components of the microcrystalline cellulose -trichlorophene (MCC -TCP) system can proceed via the formation of intermolecular (hydrogen) bonds and even covalent bonds, depending on the intensity of treatment and the method of mixing. These interactions have predominantly a topochemical character. For this reason, various hypotheses concerning the possible formation of new chemical substances possessing certain molecular and chemical structure and definite physicochemical properties are not valid. This conclusion is confirmed by the data of IR spectroscopy, x-ray diffraction, and electron microscopy. Therefore, such MCC -TCP reaction products may possess no specific biological activity different from that of the system components. Only the formation of a relatively small number of bonds between MCC and TCP preserves the chemical activity of TCP at a significantly increased drug release time.

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Sustained release of nitrofurantoin from inert wax matrixes

El-Shanawany

1993

Journal of Controlled Release

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Sustained release from inert matrices I. Effect of macrocrystalline cellulose on aminophylline and theophylline release

Cited by 12 publications

References 6 publications

Soy Matrix Drug Delivery Systems Obtained by Melt-Processing Techniques

Soy Matrix Drug Delivery Systems Obtained by Melt-Processing Techniques

Molecular and supramolecular interactions in systems based on microcrystalline cellulose and trichlorophene

Sustained release of nitrofurantoin from inert wax matrixes

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