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Ethylene vinyl acetate membranes

Several authors have discussed the ion exchange potentials and membrane properties of grafted cellulose [135,136]. Radiation grafting of anionic and cationic monomers to impart ion exchange properties to polymer films and other structures is rather promising. Thus, grafting of acrylamide and acrylic acid onto polyethylene, polyethylene/ethylene vinyl acetate copolymer as a blend [98], and waste rubber powder [137,138], allows... [Pg.512]

RATE-CONTROLLII ETHYLENE-VINYL ACETATE COPOLYMI MEMBRANES... [Pg.521]

The hormone-releasing devices have a closer resemblance to standard methods of sustained release because they involve the release of a steroid compound by diffusion [198,199]. The Progestasert, a reservoir system, is shown in Fig. 16. Progesterone, the active ingredient, is dispersed in the inner reservoir, surrounded by an ethylene/vinyl acetate copolymer membrane. The release of progesterone from this system is maintained almost constant for 1 year. The effects of release are local, with none of the systematic side effects observed with orally administered contraceptives [200-207]. [Pg.524]

Gas permeation properties of ethylene vinyl acetate-silica nanocomposite membranes./. Membr. Sd., 322 (2), 423 28. [Pg.350]

Nondegradable polymers are also useful as matrices for ocular implants. This application requires the polymer to be hydrophilic, to minimize local tissue irritation. Need for ocular implants stems from the challenges posed to conventional ocular medicines (i.e., eye drops) such as rapid dilution, tear washout, poor patient compliance, and limited bioavailability. Ocular implants from hydrophilic polymer matrices that provide localized sustained release may overcome the above limitations. The first polymeric sustained release product to reach the market was Ocusert , a pilocarpin sustained release ocular implant developed by Alza. Ocusert has the drug reservoir as a thin disc of pilocarpine-alginate complex sandwiched between two transparent discs of microporous membrane fabricated from ethylene-vinyl acetate copolymer. The microporous membranes permit the tear fluid to penetrate into the drug reservoir compartment to dissolve pilocarpine from the complex. Pilocarpine molecules are then released at a constant rate of 20 or 40 pg/hr for a four- to seven-day management of glaucoma. [Pg.353]

The most current method of nitroglycerin application is a transdermal device or skin patch. A cross section of such a patch is illustrated in Figure 6. The patch is actually a multi-layered polymer stack. The semipermeable membrane which comes in contact with the skin is usually composed of an ethylene-vinyl acetate copolymer or polypropylene. The reservoir contains the drug in a hydrogel or polymer matrix or solvent (the material must be chosen to insure uniform delivery). Examples of some solvents used include dimethyl sulfoxide (DMSO), sodium lauryl sulfate (SDS - a detergent) and propylene glycol/oleic acid. [Pg.28]

Rate-controlling ethylene-vinyl acetate copolymer membranes... [Pg.370]

Ethylene/vinyl acetate membrane — Pilocarpine-core reservoir —Titanium dioxide-white ring... [Pg.1084]

In this controlled-release ocular insert, the drug reservoir is a thin disc of pilocarpine-alginate complex sandwiched between two transparent discs of micro-porous membrane fabricated from ethylene-vinyl acetate copolymer (Fig. 5). The microporous membranes permit the tear fluid to penetrate into the drug... [Pg.1084]

In fact, a few polymers can satisfy all the above conditions. Table 7 shows the polymer materials for ratecontrolling membranes and their suitability for TDS. Among them, PE and ethylene vinyl acetate (EVA) membranes are the most commonly used for reservoir systems. [Pg.2932]

Ethylene vinyl acetate copolymers are used as membranes and backings in laminated transdermal drug delivery systems. They can also be incorporated as components in backings in transdermal systems. Ethylene vinyl acetate copolymers have been shown to be an effective matrix and membrane for the controlled delivery of atenolol triprolidine, and furose-mide. The system for the controlled release of atenolol can be further developed using ethylene vinyl acetate copolymers and plasticizers. ... [Pg.285]

Ethylene vinyl acetate is mainly used in topical pharmaceutical applications as a membrane or film backing. Generally it is regarded as a relatively nontoxic and nonirritant excipient. [Pg.285]

Shin SC, Lee HJ. Controlled release of triprolidine using ethylene-vinyl acetate membrane and matrix systems. Eur J Pharm Biopharm 2002 54(2) 201-206. [Pg.286]

Performance improvement of polysulfone ultrafiltration membrane has been achieved by blending with PANI-NFs [457]. Conducting blends of nanostruetured PANI and PANI-clay nanocomposites with ethylene vinyl acetate as host matrix have been prepared [458]. A new conducting hybrid biocompatible composite material of PANI-NFs well dispersed in a collagen matrix was fabricated with various PANI-NFs/eoUagen ratios [459]. PANI-NFs doped by protonic acids can be efficiently dispersed in vinylidene fluoride-trifluoroethylene copolymers [460]. Fabrication of MWCNTs/PANI-NF nanocomposites via electrostatic adsorption in aqueous colloids has been reported [143]. A PANI-NFs/ carbon paste electrode was prepared via dopping PANI-NFs into the carbon paste [461]. [Pg.65]

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See also in sourсe #XX -- [ Pg.285 ]



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