Drug Release Analysis Research Articles

Finite element analysis of diffusional drug release from complex matrix systems. I.: Complex geometries and composite structures

The finite element method (FEM) was applied to the problems of diffusion-controlled drug release from complex matrix systems. These systems consisted of complex geometries and composite structures with various boundary conditions. The finite element procedures were first verified using analytical solutions for simple geometries, i.e., spherical, planar, and cylindrical geometries, under the perfect sink condition and in a well-stirred finite volume. The finite element solutions agreed very well with the exact solutions. The procedures were then used to analyze drug release into a finite volume from matrix devices of complex geometries including a convex tablet, a hollow cylinder, a doughnut-shaped ring, and an inward-release hemisphere. The effect of mixing on the release kinetics was studied by comparison of release profiles in a well-stirred finite volume with those in a poorly-stirred finite volume. Variation of drug concentration distribution with time within the matrix devices and in the dissolution medium was illustrated. The effect of composite structure on the release kinetics was also investigated using the devices made of two or more materials, such as composite pessaries, coated elastomer rings, and multi-layered tablets.

Interpenetrating hydrogel networks based on gelatin and polyacrylamide: Synthesis, swelling, and drug release analysis

AbstractInterpenetrating hydrogel network has been synthesized from gelatin and polyacrylamide by cross‐linking with their respective cross‐linking agents. The swelling behavior of this Interpenetrating polymer network (IPN) system was analyzed in water and in citric acid‐phosphate buffer solution at various pH. The effect of temperature on swelling behavior of these gels has been analyzed by variation from 25 to 60°C at physiological pH. The drug release behavior of these gels was also analyzed with temperature variation at physiological pH. © 1994 John Wiley & Sons, Inc.

Mathematical analysis of drug release from a coated particle

The release of a drug from a coated spherical particle into a well-stirred extraction medium has been analyzed exactly in dimensionless forms and the results have been discussed over wide ranges of variables. Concentration profiles in the matrix, coating and extraction medium have been computed and illustrated for various diffusivity ratios, relative thicknesses of coating, and volume of extraction medium. The change that may be expected in dimensionless cumulative release curves is finite for all diffusivity ratios. The magnitudes of diffusivity ratio that may cause substantial changes in the cumulative release curve are greater for thicker coating. Special cases have been derived from the general solutions and the results are compared with those available in the literature.