Cellulose acid phthalate

Cellulose acid phthalate, I, 320 Cellulose acid succinate, I, 320 Cellulose benzoate, I, 320 Cellulose carbamates, N-derivatives, I, 321... 

Mixed cellulose esters containing the dicarboxylate moiety, eg, cellulose acetate phthalate, have commercially useful properties such as alkaline solubihty and excellent film-forming characteristics. These esters can be prepared by the reaction of hydrolyzed cellulose acetate with a dicarboxyhc anhydride in a pyridine or, preferably, an acetic acid solvent with sodium acetate catalyst. Cellulose acetate phthalate [9004-38-0] for pharmaceutical and photographic uses is produced commercially via the acetic acid—sodium acetate method. 

Mixed esters containing the dicarboxylate moiety, eg, cellulose acetate phthalate, are usually prepared from the partially hydroly2ed lower aUphatic acid ester of cellulose in acetic acid solvent by using the corresponding dicarboxyhc acid anhydride and a basic catalyst such as sodium acetate (41,42). Cellulose acetate succinate and cellulose acetate butyrate succinate are manufactured by similar methods as described in reference 43. 

Benzoic acid cellulose acetate phthalate chlorpropamide ibuprofen indomethacin nicotinic acid oxyphenbutazone phosphoric acid phenylbutazone and salicylic acid. 

Cellulose (Figure 8.19) may be extracted from wood pulp, and is usually partially hydrolysed with acid to give microcrystalline cellulose. These materials are used as tablet diluents. Semi-synthetic derivatives of cellulose, e.g. methylcellulose, hydroxymethylcellulose, and carboxymethylcellulose, are used as emulsifying and suspending agents. Cellulose acetate phthalate is cellulose with about half the hydroxyl groups acetylated, and the remainder esterified with phthalic acid. It is used as an acid-resistant enteric coating for tablets and capsules. 

As previously discussed, food effects are an important parameter for enteric-coated systems, especially for drugs, that are sensitive to food. Pancreatic enzyme-containing products fail when they come in contact too early with lipids, proteins, and carbohydrates present in food. The clinical efficacy of pancreatic enzymes formulated as enteric-coated tablets was investigated in man and dog [44], The enteric materials examined were hydroxypropyl methylcellulose phthal-ate (HPMCP), cellulose acetate phthalate (CAP), and the methacrylic acid copolymer USP/NF Type C. In vivo behavior monitored by x-ray scintigraphy showed clear differences between the three coating formulations. HPMCP-coated products adhered to the gastric mucosa, whereas CAP and methacrylate copolymer... 

Naproxen sodium tablets were used in an in vivo-in vitro evaluation with four different polymeric dispersions, cellulose acetate phthalate (CAP), cellulose acetate trimellitate (CAT), 50 50 CAP/CAT, and methacrylic acid copolymer [64], The study indicated that coating material that dissolves at a more acidic pH in vitro (such as CAT at pH 4.5) will also dissolve at a more acidic pH in vivo (i.e., the coating dissolves higher up in the GI tract). In addition, it was found that aging did not markedly affect dissolution characteristics of CAT or methacrylic acid copolymer-coated tablets. 

Several polymers were found to fit all or most of the above criteria and were used to prepare the carrier films. Many polymers have been used for this purpose, viz., ethyl cellulose, poly(y-benzyl glutamate), poly(vinyl acetate), cellulose acetate phthalate, and the copolymer of methyl vinyl ether with maleic anhydride. In addition to the base polymers, plasticizers were often needed to impart a suitable degree of flexibility. Plasticizers, which are found to be compatible with polymeric materials include, acetylated monoglycerides, esters of phthalic acid such as dibutyl tartarate, etc. An excipient was usually incorporated into the matrix of the carrier films. The excipients used were water-soluble materials, which are capable of creating channels in the polymer matrix and facilitate diffusion of the drug. PEGs of different molecular weights were used for this purpose. 

Cellulose acetate phthalate Esterified cellulose with about 20 and 35% acetate and phthalate groups, respectively Free acid form dissolves in organic solvents and only the alkali metal salts are water soluble Protective coating of tablets, insoluble in stomach but soluble in intestine fluids... 

Glaessner, Austria, 1931), ammoniacal bleached shellac (Wruble, 1933), stearic acid, carnauba wax, petrolatum, elm bark, and agar (Miller, 1935, and Worton, 1938), and abietic, oleic, and benzoic acids with methyl abietate (Eldred, 1937). Since 1940, research on enteric coatings has focused on the synthesis of resinous polymers, which are insoluble in acids, such as cellulose acetate phthalate (Hiatt, 1940) and a glycerol-stearic acid-phthalic anhydride ester (Volweiler and Moore, 1940). 

Cellulose acetate phthalate is a cellulose in which about half the hydroxyl groups are acetylated, and about a quarter are esterified with one of two acid groups being phthalic acid, where the remaining acid group is free. See Section 5. 

Cellulose acetate phthalate is a hygroscopic, white to off-white, free-flowing powder, granule, or flake. It is tasteless and odorless, or might have a slight odor of acetic acid. 

Cellulose acetate phthalate (CAP) is used as an enteric film coating material, or as a matrix binder for tablets and capsules.Such coatings resist prolonged contact with the strongly acidic gastric fluid, but dissolve in the mildly acidic or neutral intestinal environment. 

Slow hydrolysis of cellulose acetate phthalate will occur under prolonged adverse conditions such as high temperatures and high humidity, with a resultant increase in free acid content, viscosity, and odor of acetic acid. However, cellulose acetate phthalate is stable if stored in a well-closed container in a cool, dry place. 

Cellulose acetate phthalate is incompatible with ferrous sulfate, ferric chloride, silver nitrate, sodium citrate, aluminum sulfate, calcium chloride, mercuric chloride, barium nitrate, basic lead acetate, and strong oxidizing agents such as strong alkalis and acids. 

Cellulose acetate phthalate is produced by reacting the partial acetate ester of cellulose with phthalic anhydride in the presence of a tertiary organic base such as pyridine, or a strong acid such as sulfuric acid. 

The enteric materials examined were hydroxypropyl methylcellulose phthal-ate (HPMCP), cellulose acetate phthalate (CAP), and the methacrylic acid copolymer USP/NF Type C. In vivo behavior monitored by x-ray scintigraphy showed clear differences between the three coating formulations. HPMCP-coated products adhered to the gastric mucosa, whereas CAP and methacrylate copolymer... 

Cellulose acetate phthalate, diallyl phthalate, dyes and pigments, herbicides, isatoic anhydride. pfceaol-phthalem, phthalimide, polyester-polyols, 4 5ulfophthaiic acid, tctrachloro and tetrabromophthafic anhydrides,-. 

Other than the esters described, the principal organic cellulose ester manufactured is cellulose acetate acid phthalate. This product is insoluble in aqueous acidic media, but because of the free acid groups present in the pendant groups, it is soluble in aqueous basic media. It is used for enteric pill coatings. 

Poly(methyl acrylate-co-methyl methacrylate-co-methacrylic acid) 7 3 1 Poly(methacrylic acid-co-methyl methacrylate) 1 2 Hydroxypropyl cellulose Ethyl cellulose Cellulose acetate butyrate Cellulose acetate phthalate Poly(ethylene oxide)... 

Cellulose acetate phthalate is a polymer typically used as enteric coating, because it is not soluble in water at acidic pH, but only at pH > 6. 

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