Characterization of the Drug Release Process by Investigation of Its Temperature Dependence

Brohede, Ulrika; Frenning, Göran; Strömme, Maria

doi:10.1002/jps.20095

Cited by 11 publications

(11 citation statements)

References 16 publications

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“…Especially in the first case, the ability of the cellulose to transport charges in a humid environment is important for the drug release process. In earlier work of ours 2,3 we have, in fact, shown that the average diffusion coefficient for the release process of Na + and Clions from the interior of compacted cellulose granules is of the same order of magnitude as the diffusion coefficient of the current carrying species in a humid (22% relative humidity) cellulose matrix where no ions have been intentionally introduced.…”

Section: Introductionmentioning

confidence: 69%

Electrodynamic Investigations of Conduction Processes in Humid Microcrystalline Cellulose Tablets

Nilsson

Strömme

2005

J. Phys. Chem. B

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The conduction mechanism in microcrystalline cellulose (MCC) tablets at varying relative humidity (RH) has been investigated by using the techniques of low frequency dielectric spectroscopy and transient current analysis at room temperature. The dependence on RH on the measured conductivity and charge carrier density indicates that a high-power-law-exponent percolation process of cations being conducted on water molecules occupying available 6-OH units on the cellulose chains is the dominating dc conduction mechanism at RH below 3 wt % of moisture content. The experimentally observed decrease in charge carrier mobility with increasing moisture content shows that protons and H3O+ ions that are being blocked at empty 6-OH sites also contribute to the charge transport process in cellulose at low moisture contents.

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Section: Introductionmentioning

confidence: 69%

Electrodynamic Investigations of Conduction Processes in Humid Microcrystalline Cellulose Tablets

Nilsson

Strömme

2005

J. Phys. Chem. B

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“…New controlled drug delivery systems in response to changes in environmental conditions, e.g., temperature [1][2][3], pH [4][5][6], and electric field [7][8][9], are being explored. Such systems which are potentially useful for various biomedical and bioengineering fields experience changes in either their structures or their intra-/intermacromolecular interactions due to external stimuli, as previously mentioned.…”

Section: Introductionmentioning

confidence: 99%

Novel pH-sensitive polyelectrolyte carboxymethyl Konjac glucomannan-chitosan beads as drug carriers

Dai

Liu

et al. 2006

Reactive and Functional Polymers

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“…In earlier work of the present authors group [2,5] it was shown that the diffusion coefficient for Na + and Cl -ions, for the release process from the interior of compacted cellulose granules is of the same order of magnitude as the diffusion coefficient of the current carrying species in a humid (22% RH) cellulose matrix, where no ions have been intentionally introduced. Brohede et al [5] suggested that the drug-release process is dominated by diffusion via a hydration shell surrounding the drug ions, due to the longer lifetime for the water molecules surrounding the small positive ions like Na + [6].…”

Section: Introductionmentioning

confidence: 89%

“…Brohede et al [5] suggested that the drug-release process is dominated by diffusion via a hydration shell surrounding the drug ions, due to the longer lifetime for the water molecules surrounding the small positive ions like Na + [6]. The lifetime for a bond between Na + and water is two orders of magnitude larger than for a bond between two water molecules [7].…”

Section: Introductionmentioning

confidence: 99%

Conductance phenomena in microcrystalline cellulose

Nilsson

2006

Phys. Status Solidi (c)

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We have investigated the conduction phenomena in compacted tablets of cellulose with varying relative humidity (RH) with techniques such as Low Frequency Dielectric Spectroscopy (LFDS) and Transient Current (TC) at room temperature. Two exponential decaying regions in the transient current measurements indicate two ionic species contributing to the conduction mechanism. A high power-law exponent of ~9 for the conductance with moisture content has been found. The mobility initially decreases with RH up to monolayer coverage, and further water vapor increases the mobility, indicating a blocking of available positions for the charge carrier ions. When the amount of water molecules present in the tablet increases one order of magnitude, the number of charge carriers increases 5-6 orders of magnitude, suggesting a transition from a power-law increase to a linear effective medium theory for the conduction. The charge carrier dependence on RH suggests that a percolating network of water molecules adsorbed to 6-OH units on the cellulose chain span through the sample. The conductivity mechanisms in cellulose are still not clear.

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Characterization of the Drug Release Process by Investigation of Its Temperature Dependence

Cited by 11 publications

References 16 publications

Electrodynamic Investigations of Conduction Processes in Humid Microcrystalline Cellulose Tablets

Electrodynamic Investigations of Conduction Processes in Humid Microcrystalline Cellulose Tablets

Novel pH-sensitive polyelectrolyte carboxymethyl Konjac glucomannan-chitosan beads as drug carriers

Conductance phenomena in microcrystalline cellulose

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