Percolative drug diffusion from cylindrical matrix systems with unsealed boundaries

Brohede, Ulrika; Valizadeh, Sima; Strömme, Maria; Frenning, Göran

doi:10.1002/jps.20915

Cited by 6 publications

(6 citation statements)

References 57 publications

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“…This is consistent with the fact that the pore sizes also decreased with increasing Al/Si ratio (see Fig. 4); it is logical that drug diffusion through the geopolymer, and therefore also drug release, is slower in a system of smaller pores [30]. Increasing aluminum content resulted in a more linear release profile, and this linear release should also be attributed to the shift towards smaller pores in the aluminum rich compositions, since it has been shown that polymeric systems with pore diameters in a range comparable with the size of the drug molecules enables zero order release [31].…”

Section: Resultssupporting

confidence: 87%

Synthetic Geopolymers for Controlled Delivery of Oxycodone: Adjustable and Nanostructured Porosity Enables Tunable and Sustained Drug Release

et al. 2011

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In this article we for the first time present a fully synthetic mesoporous geopolymer drug carrier for controlled release of opioids. Nanoparticulate precursor powders with different Al/Si-ratios were synthesized by a sol-gel route and used in the preparation of different geopolymers, which could be structurally tailored by adjusting the Al/Si-ratio and the curing temperatures. In particular, it was shown that the pore sizes of the geopolymers decreased with increasing Al/Si ratio and that completely mesoporous geopolymers could be produced from precursor particles with the Al/Si ratio 2∶1. The mesoporosity was shown to be associated with a sustained and linear in vitro release profile of the opioid oxycodone. A clinically relevant release period of about 12 h was obtained by adjusting the size of the pellets. The easily fabricated and tunable geopolymers presented in this study constitute a novel approach in the development of controlled release formulations, not only for opioids, but whenever the clinical indication is best treated with a constant supply of drugs and when the mechanical stability of the delivery vehicle is crucial.

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Section: Resultssupporting

confidence: 87%

Synthetic Geopolymers for Controlled Delivery of Oxycodone: Adjustable and Nanostructured Porosity Enables Tunable and Sustained Drug Release

et al. 2011

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“…In addition, an upper threshold was observed, above which the matrix no longer remained intact after drug release. Subsequent work in this field has focused on aspects such as the fractal dimensions of pore networks (Bonny and Leuenberger, 1993), particle size and drug/excipient particle size ratio (Caraballo et al, 1996;Millán et al, 1998) and three-dimensional release (Brohede et al, 2007).…”

Section: Percolation Effectsmentioning

confidence: 99%

Modelling drug release from inert matrix systems: From moving-boundary to continuous-field descriptions

Frenning

2011

International Journal of Pharmaceutics

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The purpose of this review is to provide a comprehensive overview of mathematical procedures that can be used to describe the release of drugs from inert matrix systems. The review focuses on general principles rather than particular applications. The inherent multiscale nature of the drug-release process is pointed out and multiscale modelling is exemplified for inert porous matrices. Although effects of stagnant layers and finite volumes of release media are briefly discussed, the systematic analysis is restricted to systems under sink conditions. When the initial drug loading exceeds the drug solubility in the matrix, Higuchi-type moving-boundary descriptions continue to be highly valuable for obtaining approximate analytical solutions, especially when coupled with integralbalance methods. Continuous-field descriptions have decisive advantages when numerical solutions are sought. This is because the mathematical formulation reduces to a diffusion equation with a nonlinear source term, valid over the entire matrix domain. Solutions can thus be effortlessly determined for arbitrary geometries by using standard numerical packages.

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“…It is therefore important to analyze and understand these interactions also with respect to identifying possible ways to alter the nanostructure of cellulose in order to achieve better control over the drug release process. Recently, a series of experimental studies – investigated the mechanisms at work in the drug release process. In these studies, NaCl was commonly used as a stand-in model for the polar drug components.…”

Section: Introductionmentioning

confidence: 99%

Binding Strength of Sodium Ions in Cellulose for Different Water Contents

2008

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The interaction strength of sodium ions (Na(+)) with cellulose is investigated from first principles for varying degrees of water content. We find that the interaction of water molecules and Na(+) can be studied independently at the various OH groups in cellulose which we categorize as two different types. In the absence of water, Na(+) forms strong ionic bonds with the OH groups of cellulose. When water molecules are anchored to the OH groups via hydrogen bonds, Na(+) can eventually no longer bind to the OH groups, but will instead interact with the oxygen atoms of the water molecules. Due to the rather weak attachment of the latter to the OH groups, Na(+) becomes effectively more mobile in the fully hydrated cellulose framework. The present study thus represents a significant step toward a first-principles understanding of the experimentally observed dependence of ionic conductivity on the level of hydration in cellulose network.

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Percolative drug diffusion from cylindrical matrix systems with unsealed boundaries

Cited by 6 publications

References 57 publications

Synthetic Geopolymers for Controlled Delivery of Oxycodone: Adjustable and Nanostructured Porosity Enables Tunable and Sustained Drug Release

Synthetic Geopolymers for Controlled Delivery of Oxycodone: Adjustable and Nanostructured Porosity Enables Tunable and Sustained Drug Release

Modelling drug release from inert matrix systems: From moving-boundary to continuous-field descriptions

Binding Strength of Sodium Ions in Cellulose for Different Water Contents

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