Enteric-coated systems

Mehta, A. Valazza, M., and Abele, S. Evaluation of fluid-bed processes for enteric coating systems. Pharm. Tech. 10(4) 46-56, 1986. 

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... 

Enteric-coated systems (ECS) utilize polymeric coatings that are insoluble in the gastric media and therefore, prevent or retard drug release in the stomach. Various types of ionizable polymers are commercially available. They dissolve at various pH ranging between 4.8 and 7.2. ECSs are generally applicable to four major types of drugs ... 

Bianchini, R. Resciniti, M. Vecchio, C. Technological evaluation of aqueous enteric coating systems with and without insoluble additives. Drug Dev. Ind. Pharm. 1991, 77(13), 1779-1794. 

Chang RK, Iturrioz G, Luo CW. Preparation and evaluation of shellac pseudolatex as an aqueous enteric coating system for pellets. Int Pharm 1990 60 171-173. 

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... 

Uses Pigment for use with Eudragit L-30D or LI 00-55 to form complete one-step enteric coating system for pharmaceuticals Features Avail, as aq.-based disp. or in dry form also avail, without plasticizer... 

The polymeric enteric coating system also has resulted in differences in drug-drug interactions compared to the immediate release product, most notably with proton pump inhibitors. Omeprazole impairs the absorption and subsequent 12-hour exposure of MMF due to its incomplete dissolution in a more basic enviromnent, while EC-MPS pharmacokinetics were unaffected [59], Likewise, the manufacturer reports EC-MPS combined with pantoprazole did not yield altered kinetics [56],... 

Delivery systems that respond to changes in pH have been known to the pharmaceutical industry for more than a century. The pH-sensitive enteric coating is probably the oldest controUed-release technology. Unna introduced an enteric tablet coating based on keratin in 1884 (108). Enteric coatings are used primarily to protect the gastric mucosa from local irritation or to ensure that tablets do not dissolve until they reach the intestine. 

Azathioprine, mycophenolate mofetil, and enteric-coated MPA are not metabolized through the CYP isozyme system therefore, they do not experience the same DDI profiles as cyclosporine, tacrolimus, and sirolimus. Azathioprine s major DDIs involve allopurinol, angiotensin-converting enzyme (ACE) inhibitors, aminosalicylates (e.g., mesalamine and sulfasalazine), and warfarin.11 The interaction with allopurinol is seen frequently and has clinical significance. Allopurinol inhibits xanthine oxidase, the enzyme responsible for metabolizing azathioprine. Combination of azathioprine and allopurinol has resulted in severe toxicities, particularly myelosuppression. It is recommended that concomitant therapy with azathioprine and allopurinol be avoided, but if combination therapy is necessary, the azathioprine doses must be reduced to one-third or one-fourth of the current dose. Use of azathioprine with the ACE inhibitors or aminosalicylates also can result in enhanced myelosuppression.11 Some case reports exist demonstrating that warfarin s therapeutic effects may be decreased by azathioprine.43-45... 

Encapsulation within an enteric coat (resistant to low pH values) protects the product during stomach transit. Microcapsules/spheres utilized have been made from various polymeric substances, including cellulose, polyvinyl alcohol, polymethylacrylates and polystyrene. Delivery systems based upon the use of liposomes and cyclodextrin-protective coats have also been developed. Included in some such systems also are protease inhibitors, such as aprotinin and ovomucoids. Permeation enhancers employed are usually detergent-based substances, which can enhance absorption through the gastrointestinal lining. 

Ingle GR, Shah T. (2005) Enteric-coated mycophenolate sodium for transplant immunosuppression. Am J Health-System Pharm (AJHP) 62 2252-2259. 

Pigment slurries are one of the major components in paints and coatings that contribute to or affect the performance of a formulation. The nature of pigment slurries makes them extremely susceptible to microbiological contamination that can degrade the final formulation. Often biodeterioration can be prevented with plant sanitation and the use of a preservative, but formulators must not rely on the precept that a particular preservative that works today will always remain effective down the road. In complex environments, contaminants can enter the system at different points, or a formulation change may render the original preservative less effective. Manufacturers must remain aware of trends in the industry to ensure their products are properly protected. 

Reactive Sputtering. Reactive sputtering is similar to reactive evaporation and reactive-ion plating in that at least one coating species enters the system in the gas phase. Examples include sputtering Al in 02 to form A O Ti in 02 to form Ti02, In—Sn in 02 to form tin-doped ln203, Nb in N2 to form NbN, Cd in H2S to form CdS, In in PH3 to form InP, and Pb—Nb—Zr—Fe—Bi—La in 02 to form a ferroelectric oxide. 

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