Performance of three-layer controlled release devices with uniform or non-uniform material properties: Experiment and computer simulation

Soulas, Dimitrios N.; Sanopoulou, M.; Papadokostaki, Kyriaki G.

doi:10.1016/j.memsci.2010.12.049

Cited by 5 publications

(6 citation statements)

References 33 publications

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“…Multilayer, composite, or coated devices, either in the form of films and tablets [1][2][3][4], or of beads and microspheres [5][6][7][8][9], are frequently considered in drug release formulations in order to control the amount and the time of administration of bioactive compounds. Moreover, these systems can be used to reduce the undesired initial burst release effect [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Lag Time in Diffusion-Controlled Release Formulations Containing a Drug-Free Outer Layer

Kalosakas

Panagopoulou

2022

Processes

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Theoretical considerations along with extensive Monte Carlo simulations are used to calculate the lag time before the initiation of diffusion-controlled drug release in multilayer planar devices with an outer layer containing no drug. The presented results are also relevant in formulations coated by a drug-free membrane as well as in other reservoir systems. The diffusion of drug molecules through the outer layer towards the release medium is considered, giving rise to the observed lag time. We have determined the dependence of lag time on the thickness and the diffusion coefficient of the drug-free outer layer, as well as on the initial drug concentration and the surface area of the planar device. A simple expression, obtained through an analytical solution of diffusion equation, provides an approximate estimate for the lag time that describes the numerical results reasonably well; according to this relation, the lag time is proportional to the squared thickness of the outer layer over the corresponding diffusion coefficient and inversely proportional to the logarithm of the linear number density of the drug that is initially loaded in the inner layer.

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Section: Introductionmentioning

confidence: 99%

Lag Time in Diffusion-Controlled Release Formulations Containing a Drug-Free Outer Layer

Kalosakas

Panagopoulou

2022

Processes

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“…The model, briefly outlined above, can be parametrized on the basis of data pertaining to the fundamental sorption and diffusion properties of the polymer–solute–solvent system, derived from literature or independent experimental measurements. In this way, it has been successfully applied to experimental data of model three-layer matrices consisting of inner cellulose layers loaded with sodium chloride and solute-free outer layers of cellulose or cellulose acetate . The cellulosic layers were loaded by equilibration to salt solutions, and release performance was studied under conditions of initially fully swollen matrices.…”

Section: Model For Mcr Systemsmentioning

confidence: 99%

“…The higher impact of C WB o , as compared to the other two parameters, is a consequence of its effect on both the solute diffusivity (eq 5) as well as the C NS o (eq 4). Note that the effect of C WB o is expected to be even more intense in systems where the functional dependence of D N on C W is stronger (see, for example, ref ).…”

Section: Theoretical Studiesmentioning

confidence: 99%

“…Accordingly, theoretical calculations pertaining to the ABA-7 and ABA-15 experimental systems, to be noted as trials II-7 and trial II-15, were performed (i) with geometrical characteristics L A / L equal to 1/2.4 (for trial II-7) and 1/2.9 (for trial II-15), based on the experimental values of Table and (ii) all other input parameters, pertaining to transport properties of both layers A and B, identical to those of trial I (Table ), except for the value of C WA o . Previous work has shown that results are very sensitive to the water uptake of the outer layers. , On the other hand, the experimental ABA matrices used in this work consist of supersaturated inner layer B, prepared by adding theophylline in the polymer mixture prior to curing, and of solute-free outer layers A cured in the absence of solute. The different preparation conditions of layers A and B are possibly responsible for the observed difference in equilibrium water uptake determined at the end of the release experiments from B-7 and B-15 matrices ( C WB o = 1.02 g/g) and upon equilibration with water of single A layers ( C WA o = 0.65 g/g).…”

Section: Theoretical Studiesmentioning

confidence: 99%

“…In this way, it has been successfully applied to experimental data of model three-layer matrices consisting of inner cellulose layers loaded with sodium chloride and solutefree outer layers of cellulose or cellulose acetate. 50 The cellulosic layers were loaded by equilibration to salt solutions, and release performance was studied under conditions of initially fully swollen matrices. The system studied here concerns drug loadings above saturation and is more complex, mainly because release experiments from initially dry matrices are studied, and thus ingress of water occurs concurrently to drug release.…”

Section: Model For Mcr Systemsmentioning

confidence: 99%

See 2 more Smart Citations

Drug Release from Poly(dimethylsiloxane)-Based Matrices: Observed and Predicted Stabilization of the Release Rate by Three-Layer Devices

Soulas

Papadokostaki

Panou

et al. 2012

Ind. Eng. Chem. Res.

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Realistic mathematical modeling can greatly facilitate the optimum design of matrix-controlled release (MCR) devices. Here, we present a practical example of a relevant methodology, based on a previously developed model for symmetrical, three-layer MCR devices. The experimental system is based on PDMS matrices incorporating 10% of poly(ethylene glycol) and loaded with theophylline. The matrices were either single-layer devices uniformly loaded with theophylline or symmetrical threelayer devices with a uniformly loaded inner layer and theophylline-free outer layers. The theophylline loads, and the geometrical characteristics of the multilayer matrices, were chosen according to general guidelines for improved uniformity of rate, previously formulated by model calculations. As anticipated, these devices were found to effectively stabilize the rate of release, as compared to the corresponding single-layer system. The main kinetic characteristics of the experimental systems were then successfully reproduced theoretically by a set of input parameters (pertaining to the transport properties of the polymer−solute−solvent system), derived mainly from the release experiments in monolithic matrices. Finally, the same input parameters were used for exploring theoretically the range of the three-layer device parameters that are expected to preserve the observed improved performance of the experimental systems.

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Proxyphylline release kinetics from symmetrical three-layer silicone rubber matrices: Effect of different excipients in the outer rate-controlling layers

Soulas

Sanopoulou

Papadokostaki

2012

International Journal of Pharmaceutics

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Performance of three-layer controlled release devices with uniform or non-uniform material properties: Experiment and computer simulation

Cited by 5 publications

References 33 publications

Lag Time in Diffusion-Controlled Release Formulations Containing a Drug-Free Outer Layer

Lag Time in Diffusion-Controlled Release Formulations Containing a Drug-Free Outer Layer

Drug Release from Poly(dimethylsiloxane)-Based Matrices: Observed and Predicted Stabilization of the Release Rate by Three-Layer Devices

Proxyphylline release kinetics from symmetrical three-layer silicone rubber matrices: Effect of different excipients in the outer rate-controlling layers

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