Open AccessJournal Article
Release of medroxyprogesterone acetate from a silicone polymer.
T. J. Roseman,William I. Higuchi +1 more
TLDR
In this paper, the physicochemical factors involved in the in vitro release of medroxyprogesterone acetate (MPA) a water-insoluble steroid embedded in a silicone rubber matrix was based upon a model system which considered the matric boundary diffusion layer.Abstract:
A study of the physicochemical factors involved in the in vitro release of medroxyprogesterone acetate (MPA) a water-insoluble steroid embedded in a silicone rubber matrix was based upon a model system which considered the matric boundary diffusion layer; extensive mathematical equations for the model are presented for planar and cylindrical cases. Initial and long-time release rates were obtained. Zones of MPA depletion were measured microscopically as a function of time and the partition coefficient of MPA was determined. Following relatively constant initial release rates a nonlinear dependence of release rates upon MPA concentration (3% 12% 24%) was found. As MPA diffused from the matrix well-defined zones of depletion developed and were photographed. Comparison of the present model to the T. Higuchi model of drug release (based on a purely matrix-controlled system) indicated that when boundary layer was considered a better fit of experimental data to theory was found. Findings suggest that the partition coefficient diffusion coefficients medroxyprogesterone acetate concentration within the polymer and agitation conditions play important roles in the release process. The applicability of the model to an in vivo system (in which slower release of MPA has been observed) is evaluated.read more
Citations
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Dissolution Mechanism of Diclofenac Sodium from Wax Matrix Granules
TL;DR: The results suggest that proper selection of rate-controlling agents based on their physicochemical properties (such as swelling ability and solubility) is important in designing WMGs with desired dissolution profiles.
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A model of dissolution-controlled, diffusional drug release from non-swellable polymeric microspheres
Ronald S. Harland,Catherine Dubernet,Jean-Pierre Benoit,Nicholas A. Peppas,Nicholas A. Peppas +4 more
TL;DR: In this paper, a new model was developed to account for the kinetics of drug release from porous, non-swellable polymeric microparticles in the case where both drug dissolution and diffusion mechanisms control the overall release process.
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Finite element analysis of diffusional drug release from complex matrix systems. I. Complex geometries and composite structures
Y. Zhou,Xiao Yu Wu +1 more
TL;DR: In this article, the authors applied the finite element method (FEM) to the problems of diffusion-controlled drug release from complex matrix systems, which consisted of complex geometries and composite structures with various boundary conditions.
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Historical perspective on advanced drug delivery: how engineering design and mathematical modeling helped the field mature.
TL;DR: Emphasis is given on the advances of biomaterials as drug delivery agents and on the use of design equations and mathematical modeling to achieve a wide range of successful systems.
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A silicone elastomer vaginal ring for HIV prevention containing two microbicides with different mechanisms of action
Susan M. Fetherston,Peter Boyd,Clare McCoy,Marcella McBride,Karen-Leigh Edwards,Stephen Ampofo,R. Karl Malcolm +6 more
TL;DR: The development of a combination antiretroviral silicone elastomer matrix-type vaginal ring for simultaneous controlled release of dapivirine, a non-nucleoside reverse transcriptase inhibitor, and maraviroc, a CCR5-targeted HIV-1 entry inhibitor is reported.
References
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Journal ArticleDOI
Mechanism of sustained‐action medication. Theoretical analysis of rate of release of solid drugs dispersed in solid matrices
TL;DR: The analyses suggest that for the latter system the time required to release 50% of the drug would normally be expected to be approximately 10 per cent of that required to dissolve the last trace of the solid drug phase in the center of the pellet.
Book
Membrane Technology and Applications
TL;DR: Overview of membrane science and technology membrane transport theory membrane and modules concentration polarization reverse osmosis ultrafiltration microfiltration gas separation pervaporation ion exchange membrane processes - electrodialysis carrier facilitated transport medical applications of membranes other membranes processed.
Journal ArticleDOI
A simple equation for description of solute release I. Fickian and non-fickian release from non-swellable devices in the form of slabs, spheres, cylinders or discs
TL;DR: In this paper, a simple exponential relation Mt/M∞ = ktn is introduced to describe the general solute release behavior of controlled release polymeric devices, where Mt is the fractional release, t is the release time, k is a constant, and n is the diffusional exponent characteristic of the release mechanism.