Slow release coatings

EMA resins and esters of these materials have received some attention as enteric coatings or slow-release coatings for medicinals. The ester... 

Medicinal slow-release coatings Methyl vinyl France 2,187,290 1974 Purdue Research Foundation... 

Iron slow-release coatings Netherlands 7,961 1966 Teikoku Hormone Mfg. 

Coatings, Paints, and Pigments. Various slightly soluble molybdates, such as those of zinc, calcium, and strontium, provide long-term corrosion control as undercoatings on ferrous metals (90—92). The mechanism of action presumably involves the slow release of molybdate ion, which forms an insoluble ferric molybdate protective layer. This layer is insoluble in neutral or basic solution. A primary impetus for the use of molybdenum, generally in place of chromium, is the lower toxicity of the molybdenum compound. 

Other. 2-Nitro-1-butanol is an excellent solvent for many polyamide resins, cellulose acetate butyrate, and ethylceUulose. It can be utilized in paint removers for epoxy-based coatings. 2-Hydroxymethyl-2-nitro-l,3-propanediol is usebil for control of odors in chemical toilets. Its slow release of formaldehyde ensures prolonged action to control odor, and there is no reodorant problem which sometimes is associated with the use of free formaldehyde. 2-Hydroxymethyl-2-nitro-l,3-propanediol solutions are effective preservative and embalming fluids. The slow Uberation of formaldehyde permits thorough penetration of the tissues before hardening. 

Erodings of Slow-Releasing Core Tablets. The sustained-dose portion of a dmg is granulated with hydrophobic materials such as waxes, fatty acids, or fatty alcohols and compressed into a core. The initial dose is added to the core by a modified sugar coating process or by compression coating. Thus, a tablet within a tablet is created. The core erodes slowly to release the active ingredient. 

The biological impact of starch capped copper nanoparticles on mouse embryonic fibroblast (3T3L1) cells in vitro) was also evaluated by various parameters. More than 85 % of the 3T3Llcells were found to be viable, even after 20 hours time exposure which implies minimum impact on cell viability and morphology. The study demonstrates dose dependent cytotoxic potential of SCuNPs, that is non cytotoxic in the nanogram dose and moderately cytotoxic in the microgram doses (Fig. 10). Comparison of SCuNPs with Cu ions and uncapped copper nanoparticles (UCuNPs) revealed that, ions are more cytotoxic than SCuNPs. This observation supports the theory of slow release of ions from starch coated nanoparticles. 

Application of nematodes in infected insect cadavers have also been described by some workers (Shapiro-Ilan et al. 2001, 2003), which enables the slow release of nematode and therefore considered effective for small-scale application. Coating the cadavers with starch and clay mixture helps in preventing rupture during storage and shipping (Shapiro-Ilan et al. 2001). 

The reason for the problems is often that the characteristics of the medication are changed. Depot formulation loses its slow release properties with increased peak-and decreased through concentrations. Enteric coating is destroyed with stomach... 

Swelling sustained-release coating polymers such as Eudragit NE 30 D, i.e. poly(ethyl-acrylate-methylmethacrylate) [101,102] or Eudragit RS [90], lead to a delay in drug release which is dependent on the thickness of the coating since these films have slow rates of swelling. 

Triazones form ammonium ions much more slowly than urea. Slow-release potassium is also being developed. A coating of sulfur seems to delay its release. For phosphorus Mg(NH4)P04 is becoming popular because it has a slower dissolution rate in the soil. Despite the simple chemicals used in most fertilizers, some interesting research and formulation work will keep chemists involved in the industry for some time to come. 

Sugar-coated products have been marketed that contain KCl in a wax matrix (Slow-K and Kaon-Ct) and are purportedly slow- and controlled-release preparations. Available evidence indicates that these slow-release forms of KCl are occasionally capable of causing local tissue damage and therefore prol5ably should be used with caution for K+ supplementation. Solutions of potassium gluconate, like the tablets, also have been associated with intestinal ulceration. Microencapsulated KCl preparations Micro-K, K-Dur) that are neither enteric coated nor contained within a wax matrix appear to be superior to the wax matrix formulation. 

Sustained release preparations of potassium chloride have been widely used to overcome the gastrointestinal side effects following medication with enteric coated tablets. Such formulation techniques delay the rate of absorption and produce a slow release of potassium chloride during the passage through the gastrointestinal tract [1,2]. 

The main applications for PVA are in textile sizing, adhesives, polymerization stabilizers, paper coating, poly(vinyl butyial), and PVA fibers. In terms of percentage, and omitting the production of PVA not isolated prior to conversion into poly(vinyl butyral), the principal applications are textile sizes, at 30% adhesives, including use as a protective colloid, at 25% fibers, at 15% paper sizes, at 15%, poly(vinyl butyral), at 10% and others, at 5%, which include water-soluble films, nonwoven fabric binders, thickeners, slow-release binders for fertilizer, photoprinting plates, sponges for cosmetic, and health care applications. 

The dissolution controlled release matrix systems provide sustained release profiles i.e., the active drugs in these systems are released continuously at a slow rate to provide a long-term therapeutic effect. Unlike diffusion controlled release coated systems, release profiles from dissolution controlled release coated systems do not follow zero-order kinetics but fall within the classification of delayed release systems,4 pulsatile or repeat-action systems,5 and sustained release systems.3... 

In recent years, interest in multiple-layered tablets as an oral controlled release system has increased. Multiple-layered tablets have some obvious advantages compared with conventional tablets. In addition to avoiding chemical incompatibibties of formulation components by physical separation, release profiles may be modified by combining layers with different release patterns or by combining slow release with immediate release layers. If the core layer of multilayered tablet is completely covered by a surrounding layer, the product is commonly referred to as a dry-coated tablet. An example is the Smartrix tablet, in which the release profile of a drug is determined by the increase in release surface caused by erosion (dissolution) of the cover layers.39... 

A pulsatile release diltiazem hydrochloride dosage form with a blend of fast, medium, and slow release fractions of a multilayered diltiazem bead was designed.32 Polymeric membrane coating was applied to modulate the time of release. The fast, medium, and slow release fractions... 

Sustained release intravitreal dexamethasone implants have a potential use in reducing ocular inflammation and treating PVR. The device consists of a 5 mg pellet of dexamethasone coated with 10% PVA and EVA giving a mean release rate of 1.2 0.1 pg/hr over a period of 5 months. A slow release daunomycin implant was fabricated by loading the polysulfone capillary fibre with 1% w/w of daunomycin in tristearin. The controlled release is attributed to the diffusion-retardant properties of the fat. An experimental evaluation of the kinetics and efficacy of this device in a rabbit model at 15 fig and 30 fig/ device resulted in a therapeutically sustained level of daunomycin for up to 21 days after device implantation. Exhausted devices have to be removed surgically, which is an important limitation. 

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