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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PHARMACEUTICAL TECHNOLOGY Combined Application of Extrusion-Spheronization and Hot-Melt Coating Technologies for Improving Moisture-Proofing of Herbal Extracts
TL;DR: The Higuchi model was the best fit for the moisture sorption of the hot-melt coating in all formulations whereas the Opadry AMB coating fitted the Nuttanan model.
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Hollow Polyaniline and Indomethacin Composite Microspheres for Controlled Indomethacin Release
Lijuan Zhang,Zhiming Zhang,Zhiming Zhang,Paul A. Kilmartin,Jadranka Travas-Sejdic,Jadranka Travas-Sejdic +5 more
TL;DR: In this article, PANI/IND composite hollow microspheres consisting of polyaniline (PANI) and indomethacin (IND) are prepared through a self-assembly process in a mixed methanol/water solutions.
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Progesterone-releasing vaginal rings for use in postpartum contraception. I. In vitro release rates of progesterone from core-loaded rings.
TL;DR: Rings of a suitable core diameter were selected to give initial release of 5 mg/24 h progesterone and sterile batches of these rings, prepared for WHO-sponsored clinical studies in post-partum, lactating women, were shown to give highly consistent and reproducible rates of in vitro drug delivery.
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Diffusion in Vitro and in Vivo of 1-(2-Chloroethyl)-3-(trans-4-methylcyclohexyl)-1-nitrosourea from Silicone Rubber Capsules, a Potentially New Mode of Chemotherapy Administration
TL;DR: Diffusion of drugs from silicone rubber capsules is a potentially new mode of chemotherapy administration that is applicable to other chemotherapeutic agents, especially those that are non-ionized and lipid soluble.
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.