Enteric coating cellulose acetate phthalate

Aquatic aqueous enteric coating (cellulose acetate phthalate, distilled acetylated monoglycerides, and poloxamer 188) Film coating for tablets and capsules Repeat-dose toxicity with routine end points (90 days—diet rat), reproduction toxicity (embryo-fetal study in rat) and genotoxicity (2 in vitro and 1 in vivo studies) No adverse toxicity, reprotoxicity, or genotoxicity 31, 32... 

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. 

The salt form of the polymer may also play a role in determining the performance of the formulation. Kane et al. [32] found that cellulose acetate phthalate was more effective than cellulose acetate trimellitate in controlling the dissolution of sulfothiazole-sodium tablets with cellulose acetate. The enteric properties of hydroxypropylmethylcellulose phthalate (HPMCP) were found to depend on the solubility of the drug that was coated. 

As another example, small microcapsules of ibuprofen were film coated with cellulose acetate phthalate and dispersed in water before administration [54], Plasma levels were as expected and did not differ from those of a conventional enteric-coated tablet. 

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... 

J. Plaizier-Vercammen, G. Suenens, Evaluation of Aquateric, a pseudolatex of cellulose acetate phthalate, for its enteric coating properties on tablets STP Pharma Sci 5 307-312 (1991). 

Enteric coatings such as poly(methacrylates) or cellulose acetate phthalate Soluble at elevated pHs Used for delayed-release formulations... 

Cellulose acetate phthalate Enteric coating agent... 

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 (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. 

Lin SY, Kawashima Y. Drug release from tablets containing cellulose acetate phthalate as an additive or enteric-coating material. Pharm Res 1987 4 70-74. 

In 1940, Eastman Kodak Company published a U.S. patent that provided one of the earliest de.scriptions of enteric coating of medicaments. The patent claimed the use of a cellulose derivative containing free carboxyl groups as an enteric film forming polymer. Specifically, the claimed enteric polymer was cellulose acetate phthalate (CAP) (34). Numerous enteric cellulose derivatives have been developed since this early account and these polymers remain as some of the most widely used for enteric coating applications. In addition to CAP these derivatives include cellulose acetate trimellitate (CAT), cellulose acetate succinate (CAS), hydroxypropyl methylcellulose phthalate (HPMCP), and hydroxypropyl methylcellulose acetate succinate (HPMCAS). The molecular structure of these polymers is depicted in Figure 1 with their respective substituent groups listed in the caption. 

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... 

C-A-P Enteric Coating Polymer. [Eastman] Cellulose acetate phthalate. 

Physicochemical studies of the solution properties of amylose benzoate by light-scattering, osmometric, and viscosimetric techniques showed that the molecules behave as coils. Factors affecting the rate of dissolution of cellulose acetate phthalate in aqueous solution are important from the point of view of use as an enteric-coating material. The removal of the benzoyl group during methanolysis is slow and concurrent with the methanolysis, " whereas deacetylation precedes methanolysis. 

Vervaet et al. investigated another example of a core-sheU microcapsule system via HME technology in 2005. 2 These researchers used HME as an alternative technique for enteric delivery. Polyvinyl acetate phthalate and hydroxypropyl methyl cellulose acetate succinate (HPMC AS) enteric coating polymers were premixed with plasticizers and extruded into hollow cylinders. A model drug was then filled into these hollow cylinders and both open ends were sealed. Dissolution... 

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