Permeation control

Membrane permeation-controlled system in which the drug permeation is controlled by a polymeric membrane Transderm-Scop (scopolamine Ciba-Geigy). 

K Ishihara, M Kobayashi, N Ishimaru, I Shinohara. Glucose induced permeation control of insulin through a complex membrane consisting of immobilized glucose oxidase and a poly(amine). Polym J 8 625-631, 1984. 

Plasma surface treatment of many polymers, including fabrics, plastics, and composites, often occurs. The production of ultra-thin films via plasma deposition is important in microelectronics, biomaterials, corrosion protection, permeation control, and for adhesion control. Plasma coatings are often on the order of 1 100 nm thick. 

SLM (poly-prop-ylene flat sheet) Analysis of permeation controlling steps from mass transfer model Membrane diffusion controlling [56]... 

Polymer membrane permeation-controlled drug delivery systems. 

Polymer Membrane Permeation-Controlled Drug Delivery Systems... 

Fig. 3 Release of drug from various shapes of pol5mer membrane permeation-controlled drug-delivery systems (A) sphere-type, (B) cylinder-type, and (C) sheet-type. In (D), the drug concentration gradients across the rate-controlling polymeric membrane and hydrodynamic diffusion layer exist in series. Both the polymer membrane, which is either porous or non-porous, and the diffusion layer have a controlled thickness and h, respectively).

Process Variable Diffusion Control Permeation Control... 

Membrane permeation-controlled transdermal drug delivery (Fig. 5.2) has been successfully applied in therapeutic systems for scopolamine (prevention of motion sickness for a 3-day period), nitroglycerin (prophylaxis against attack of angina pectoris over a 24-h period), clonidine (control of hypertension for a 7-day period), and fentanyl (control of constant pain for 72 h). 

The insoluble cellulose derivatives utilized for permeation control of various species (e.g. oxygen and water vapor transport in coated pharmaceuticals, contact lenses, packaging, or water and solute transport through semi-permeable membranes in reverse osmosis, as well as drug release from reservoir systems) differ considerably in their permeability characteristics according to the type and extent of substitution, as well as their molar mass. However, very few comparative data are available from the literature on the polymers actually used in biological applications. Recently, new results have been published. Thus, Sprockel et al. [142] determined the water vapor transmission through various CA, CAT, CAB and CAPr films at different relative humidities (Table 22). 

In order to avoid organic solvents for the coating of the osmotic cores, an aqueous CA dispersion has been developed (see Sect. 4.1) and its performance has been investigated as water permeation controlling membrane for potassium chloride tablets [133]. The release rate could be modulated by varying the type and amount of platicizer, the thickness of the membrane or the coating temperature (Fig. 24). 

K. Ishihara, N. Hamada, S. Kato and I. Shinohara, Photoresponse of the release behavior of an organic compound by a azoaromatic polymer device, J. Polym. Sci., Polym. Chem. Ed., 1984, 22, 881 K. Ishihara and I. Shinohara, Photoinduced permeation control of protein using amphiphilic azoaromatic polymer membrane, J. Polym. Sci., Polym. Lett. Ed., 1984, 22, 515-518 J. Matejka, M. Ilavsky, K. Dusek and O. Wichterle, Photochemical effects in cross-linked photochromic polymer, Polymer, 1981, 22, 1511. 

Shown in Fig. 6 is the dependence of molecular flux on polymer film thickness. The observed inverse correlation is characteristic of permeation-controlled transport. In other words, fluxes are limited by rates of diffusion through the film rather than partitioning from the solution to the film. Similar behavior has been observed for molecular aggregate films. 

Diffusion of atoms, molecules, and ions control many processes in glasses, including ionic diffusion, ion exchange, electrical conduction, chemical durability, gas permeation, and permeation-controlled reactions. Since the mechanisms underlying all of these processes are based on similar principles, a fundamental understanding of diffusion phenomena serves as the basis for understanding all diffusion-controlled properties of glasses. 

Permeation control through stimuli-responsive polymer membrane prepared by plasma and radiation grafting techniques... 

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