Ethylcellulose, preparation

Specifications and Standards Test Methods. Ethylcellulose is cleared foi many apphcations in food and food contact under the Eedeial Eood, Dmg, and Cosmetic Act, as amended. Examples include binder in dry vitamin preparations for animal feed, coatings and inks for paper and paperboard products used in food packaging, and closures with sealing gaskets for food containers (44). Methods of analyses ate given in ASTM D914-72 (19), NationalFonmila XIV, and Food Chemicals Codex II. 

The formation of ethylcellulose nanoemulsions by a low-energy method for nanoparticle preparation was reported recently. The nanoemulsions were obtained in a water-polyoxyethylene 4 sorbitan monolaurate-ethylcellulose solution system by the PIC method at 25 °C [54]. The solvent chosen for the preparation of the ethylcellulose solution was ethyl acetate, which is classed as a solvent with low toxic potential (Class 3) by ICH Guidelines [78]. Oil/water (O/W) nanoemulsions were formed at oil/ surfactant (O/S) ratios between 30 70 and 70 30 and water contents above 40 wt% (Figure 6.1). Compared with other nanoemulsions prepared by the same method, the O/S ratios at which they are formed are high, that is, the amount of surfactant needed for nanoemulsion preparation is rather low [14]. For further studies, compositions with volatile organic compound (VOC) contents below 7 wt% and surfactant concentrations between 3 and 5 wt% were chosen, that is, nanoemulsions with a constant water content of 90% and O/S ratios from 50 50 to 70 30. 

Chen, H Wu, J.-C. and Chen, H.-Y. (1995) Preparation of ethylcellulose microcapsules containing theophylline by using emulsion non-solvent addition method. Journal of Microencapsulation, 12, 137-147. 

Spemarth, L. and Magdassi, S. (2007) Preparation of ethylcellulose nanoparticles from nano-emulsion obtained hy inversion at constant temperature. Micro el Nano Letters, 2, 90-95. 

For use as a plastics material, in lacquers, or for the preparation of water-insensitive films or filaments, ethylcellulose of a relatively high degree of substitution (1.8-2.8) and the aralkyl ether, benzylcellulose (degree of substitution 1.4-2.5) have had the greatest commercial development. 

Ethylcellulose is made commercially by the action of ethyl chloride on an alkali cellulose prepared by steeping cotton linters or wood pulp... 

The low-substituted hydroxyethylcellulose which, like methyl- and ethylcellulose, is soluble in alkali, particularly when cooled, has much to recommend it from an industrial point of view. It can be formed by the action of only small quantities (0.25 to 0.5 moles) of ethylene oxide on alkali cellulose.47 The reaction product need not be isolated since there are no salts formed, but may be diluted with water or weak alkali to give a spinning solution. The product should therefore be quite cheap. Preparation and properties of hydroxyethylcellulose have been discussed by Schorger and Shoemaker.47... 

Polyamide, collodion (cellulose nitrate), ethylcellulose, cellulose acetate butyrate or silicone polymers have been used for preparation of permanent microcapsules. This method offers a double specificity due to the presence of both the enzyme and a semipermeable membrane. Moreover, it allows simultaneous immobilization of many enzymes in a single step and the surface area for contacting the substrate and the catalyst is large. The need of high protein concentration and the restriction to low molecular weight substrates are the main limitations of enzyme microencapsulation. 

Fig. 1 Chemical structures of the polymers commonly used for preparation of beads poly (styrene-co-maleic acid) (=PS-MA) poly(methyl methacrylate-co-methacrylic acid) (=PMMA-MA) poly(acrylonitrile-co-acrylic acid) (=PAN-AA) polyvinylchloride (=PVC) polysulfone (=PSulf) ethylcellulose (=EC) cellulose acetate (=CAc) polyacrylamide (=PAAm) poly(sty-rene-Wocfc-vinylpyrrolidone) (=PS-PVP) and Organically modified silica (=Ormosil). PS-MA is commercially available as an anhydride and negative charges on the bead surface are generated during preparation of the beads...

Amylose, another natural polysaccharide, prepared under appropriate conditions, is not only able to produce films, but is also found to be resistant to the action of pancreatic a-amylase while remaining vulnerable to the colonic flora [82]. However, incorporation of ethylcellulose was necessary to prevent premature drug release through simple diffusion [83], In vitro release of 5-aminosalicylic acid from pellets coated with a mixture of amylose-ethylcellulose in a ratio of 1 4 was complete after 4 hr in a colonic fermenter. By contrast, it took more than 24 hr to release only 20% of the drug under conditions that mimic that of the stomach and of the small intestine. 

A formulation containing an anti-inflammatory agent (diclofenac sodium), two inert matrices (ethylcellulose and polyvinyl chloride), a lubricant (magnesium stearate) and talc was optimized and prepared by a double compression process. 

Two polymers were incorporated in the inert matrix system ethylcellulose and polyvinyl chloride. The processes used to prepare tablets containing such polymers often include direct compression [4-6], wet granulation [7,8], coating [9-11] and, rarely, dry granulation [12]. 

Ethylcellulose [.9004-57-3 ], a cellulose either (qv), as prepared commercially, ie, of high DS, is thermoplastic and has a low density (1.14 g/cm3). It forms films of good thermostability and excellent flexibility and toughness. Ethylcellulose is used in lacquers, inks, and adhesives and is combined with waxes and resins in the preparation of hot-melt plastics. It is also used as a pharmaceutical tablet binder. 

Carboxym ethylcelluloses (CMC). Carboxymethylcellulose [9004-42-6] (CMC) is the carboxymethyl ether of cellulose. To prepare CMC, cellulose is steeped in sodium hydroxide solution, and the so-called alkali cellulose is treated under controlled conditions with sodium monochloroacetate to form the sodium salt of carboxymethylcellulose and sodium chloride. Therefore, the CMC of commerce is actually sodium carboxymethylcellulose... 

Block and graft copolymers were prepared by Akutin, Parlashke-vich, Kogan, Kalinina, and Menes (128) by the use of ultrasonics on solutions of fluorine containing polymers or polysiloxanes on one hand and polymethyl methacrylate, polyvinyl chloride, ethylcellulose on the other. 

A unique idea is the use of a pressure-controlled capsule in colonic targeting. The inner surface of this capsule is coated with ethylcellulose. Capsules prepared in this way do not disintegrate in the stomach and small intestine but... 

Methylcellulose solutions generally form gels at higher temperatures. The gelation temperature is increased when hydroxyethyl or hydroxypropyl groups are introduced into the methylcellulose (cf. Section 9.6.2). Hy-droxyethylmethylcellulose and hydroxypropylmethylcellulose are prepared industrially by the reaction of alkali cellulose first with ethylene oxide or propylene oxide and then with methyl chloride. Similarly, hydroxyethyl-ethylcellulose is prepared by consecutive ethylene oxide and ethyl chloride treatments. Cellulose ethers with both methyl and ethyl groups have also been manufactured. 

Methyl-and ethylcelluloses are prepared by reacting purified woodpulp or cotton linters having a high a-cellulose content with aqueous sodium hydroxide and then with methyl chloride or ethyl chloride according to the following scheme ... 

Niwa, K., Takaya, T., Morimoto, T., and Takada, K. (1995), Preparation and evaluation of a time-controlled release capsule made of ethylcellulose for colon delivery of drugs, J. Drug Target., 3, 83-89. 

Wu PC, Huang YB, Chang JI, et al. Preparation and evaluation of sustained release microspheres of potassium chloride prepared with ethylcellulose. Int J Pharm 2003 260 115-121. 

Ethylcellulose is prepared by treating purified cellulose (sourced from chemical-grade cotton Enters and wood pulp) with an alkaline solution, followed by ethylation of the alkali cellulose with chloroethane as shown below, where R represents the cellulose radical ... 

Kulvanich P, Leesawat P, Patomchaiviwat V. Release characteristics of the matrices prepared from co-spray-dried powders of theophylline and ethylcellulose. Drug Dev Ind Pharm 2002 28 727-739. 

Research was undertaken to develop a controlled release tablet of naproxen using ethylcellulose and both methods of wet granulation and solid dispersion were compared for effectiveness. Naproxen level was kept constant at 16% while ethylcellulose content was varied from 6% to 28% in the formulations. While both methods were successful at producing formulations with drug release profiles of at least 12 hours, the amount of ethylcellulose required to prepare such formulations was 33% less using the solid dispersion method. While none of the formulations released 100% of the drug, a cumulative 88% of naproxen was released from the solid dispersion formulation, compared with 84% from the wet granulation formulation (50). 

Ruiz N, Ghaly ES. Mechanisms of drug release from matrices prepared with aqueous dispersion of ethylcellulose. Drug Dev Ind Pharm 1997 23(l) I13-7. 

Name Ethylcellulose Sample preparation Solid film, potassium bromide disk... 

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