Coatings ethylcellulose

When ketoprofen was loaded with chitosan-coated ethylcellulose microparticles and the plain ethylcellulose microparticles, similar findings were obtained. Although ketoprofen is well absorbed from the GI tract, chitosan appears to influence the absorption profile. Chitosan allowed the particles to make contact with the mucosal membrane and be retained at adhesive sites, which means that the drug remains in the small intestine longer. This facilitated the absorption of ketoprofen in chitosan-coated microparticles loaded with ketoprofen. Chitosan is considered to improve the absorption properties of plain microparticles [33]. 

Takishima, J., H. Onishi, and Y. Machida. 2002. Prolonged intestinal absorption of cephradine with chitosan-coated ethylcellulose microparticles in rats. Biol Pharm Bull 25 1498. 

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. 

Some tablets combine sustained-release and rapid disintegration characteristics. Products such as K-Dur (Key Pharmaceuticals) combine coated potassium chloride crystals in a rapidly releasing tablet. In this particular instance, the crystals are coated with ethylcellulose, a water-insoluble polymer, and are then incorporated into a rapidly disintegrating microcrystalline cellulose (MCC) matrix. The purpose of this tablet is to minimize GI ulceration, commonly encountered by patients treated with potassium chloride. This simple but elegant formulation is an example of a solid dosage form strategy used to achieve clinical goals. 

An improvement in this system is to coat the ion-exchange resin with a hydrophobic rate-limiting polymer, such as ethylcellulose or wax [43], These systems rely on the polymer coat to govern the rate of drug availability. 

FMC designs one such water-soluble coating for timed-release medications — Aquacoat ECD, a 30% by weight aqueous dispersion of ethylcellulose. This polymer is used to coat drug-layered beads that are delivered using gelatin capsules... 

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. 

Ethylcellulose or Eudra-git RS with galactoman-nans, p-cyclodextrin, glassy amylose, inulin Cellulose ethers, Eudragit sustained-release coatings... 

Hard gelatin capsule with inner ethylcellulose coating... 

Figure 16 Comparison of drug release characteristics of pellets coated with an aqueous ethylcellulose dispersion using a laboratory-, pilot-, and production-scale Wurster process.

Effective product and process optimization play a prominent role in any successful scale-up study. As an illustration, this case study summarizes the initial development, and subsequent scale-up, of a Wurster process designed to facilitate the application of an aqueous ethylcellulose dispersion to drug-loaded pellets. At the same time, it was intended to deal, up front, with some of the idiosyncrasies of such a coating system that often influence the functionality of the final dosage form. 

Vesey CF, Porter SC. Modified-release coating of pellets with an aqueous ethylcellulose-based coating formulation coating process considerations. Proceedings of the 13th Annual Meeting Exposition of AAPS, San Francisco, 1998. 

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]. 

The exposed surface of the tablet (barrier plus the second drug layer) was then coated by spraying a 5% w/v solution of ethylcellulose in 1 1 methyl alcohol dichloromethane in order to obtain a film of thickness 0.20 0.05 mm. 

Fig. 1—Passage of ethylcellulose-coated pellets through the gastrointestinal tract in six healthy volunteers. The position of the foremost part of the dose has been numbered according to Table 1. Each point represents the mean SD., p< 0. 01 , /><0.001.

Aquacoat ECD (ethylcellulose polymer, acetyl alcohol, and sodium lauryl sulfate in water) Coating for tablets and capsules Repeat-dose toxicity with routine end points (90 days—oral rat) and reproduction toxicity (embryo-fetal study in rat) No adverse findings for general toxicity or reprotoxicity 29, 30... 

Materials that form a permeable membrane include fats, bee wax, carnauba wax, cetyl alcohol, cetylsteryl alcohol, zein, acrylic esters, silicone elastomers, and ethylcellulose (14). Aqueous dispersions of water-insoluble polymers are commonly used for sustained-release film coatings. Examples of commercially available aqueous polymer dispersions include Surelease-containing ethylcellulose, Aquacoat-containing... 

Wood pulp(For Use in Explosives) 9)JAN-C-677 Cellulose, Regenerated Strip(For Use in Ammunition) 10)US Military Specification MIL-C-20301, Cellulose Acetate(For Use in Propellants) 11) MlL-C-5537A(l), Cellulose Acetate ButyratefFor Use in the Manufacture of Organic Protective Coatings) 12)MIL-E-L 0853B(Ethylcellulose)... 

While particle size continues to be the physical property most frequently determined by NIR spectroscopy, several other parameters including the dissolution rate and the thickness and hardness of the ethylcellulose coating on theophylline tablets have also been determined using NIR, all with good errors of prediction.94 Tablet hardness, which dictates mechanical stability and dissolution rate, has been determined in hydrochlorothiazide tablets.95... 

Parikh, N.H., S.C. Porter, and B.D. Rohera. 1993. Aqueous ethylcellulose dispersion of ethylcellulose. I. Evaluation of coating process variables. Pharm Res 10 525. 

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... 

EOF can be suppressed by coating the channel surface with methylhydroxy-ethylcellulose (MHEC) [631], orphotopolymerized polyacrylamide [415]. Reversal of EOF was also achieved, e.g., the PMMA surface was modified with N-lithioethylenediamine or N-lithiodiaminopropane [1063] or the PDMS surface was coated by hydrophobic interaction with TBA+ [302]. 

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