Cellulose HPMCP

FIGURE 18.10 Inhibitory effect of polymers on recrystallization of nifedipine (NP) from a supersaturated solution at pH 6.8. HPMCAS, hydroxypropylmethyl cellulose acetate succinate HPMC, hydroxypropylmethyl cellulose HPMCP, hydroxypropylmethyl pthate PVP, polyvinyl pyrrolidone MAEA, methacrylic acid ethyl acrylate copolymer. (From Tanno, F., Y. Nishiyama, H. Kokubo, S. Obara. ZWMjDev Ind Pharm30 13. 

Cellulose acetate phthalate (CAP) Hydroxypropylmethyl cellulose (HPMCP) Poly(methacrylates)... 

The most commonly used polymers are cellulose acetate phthalate [9004-38-0] (CAP), poly(vinyl acetate phthalate) [34481-48-6] (PVAP), hydroxypropylmethyl-ceUulosephthalate [71138-97-1] (HPMCP), and polymethacrylates (111) (see Cellulose esters). Acrylate copolymers are also available (112). Eigure 11 shows the dissolution behavior of some commercially available enteric materials. Some manufacturers supply grades designed to dissolve at specific pH values with increments as small as 0.5 pH unit (113). 

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 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... 

Cellulose phthalate hydroxypropyl methyl ether HPMCP hydroxypropyl methylcellulose benzene-1,2-dicar boxy late 2-hydroxypropyl methylcellulose phthalate methylhydroxypro-pylcellulose phthalate. 

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... 

Cellulose esters or ethers such as methylcellulose (MC), ethylcellulose (EC), hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), hydroxypropyl methylcellulose/hypromellose (HPMC), hypromeUose phthalate (HPMCP), hypromellose acetate phthalate (HPMCAP), hypromellose acetate succinate (HPMCAS), cellulose acetate (CA) and derivates Poly (methyl) methacrylates (Eudragit L, S, E, RS/ RL)... 

Wang M, Wang L and Huang Y (2007), Electrospun hydroxypropyl methyl cellulose phthalate (HPMCP)/erythromycm fibers for targeted release in intestine ,/AppZ Polym Sci, 106(4), 2177-2184. DOI 10.1002/app.25666. 

Hydroxypropyl methyl-ceUulose phthalate (HPMCP) Cellulose ethers anionic 137 °C (for HP-50) 133 °C (for HP-55) 80,000- 130,000 Above pH 5.0 Hygroscopic 28 185 °C Hot melt extrusion Spray drying... 

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