The enteric layer is a polymer barrier used in oral medications that prevents dissolution or disintegration in the stomach environment. It helps either by protecting medications from the acidity of the stomach, the stomach from the detrimental effects of the drug, or to releasing the drug after the stomach (usually in the upper tract of the intestine). Some drugs are unstable on the pH of stomach acid, and need to be protected from degradation. Enteric coatings are also an effective method for getting drug targeting (such as shock-resistant drugs). Other drugs such as some anthelmintics may need to reach high concentrations in certain parts of the intestine. Enteric coatings may also be used during the study as a research tool to determine drug absorption. Enteric-coated drugs are associated with the "pending action" dosage form category. From a pharmacological point of view the term "enteric coating" is not entirely correct, as gastric resistance can also be obtained by adding the enteric polymeric system to the dosage matrix. Tablets, mini tablets, pellets and granules (usually filled into capsule skin) are the most common forms of enteric-coating preparations.
Video Enteric coating
Description
Most enteric coatings work by presenting a stable surface at the very acidic pH found in the abdomen, but decomposing rapidly at higher pH. For example, they will not dissolve in stomach acid (pH ~ 3), but they will be in an alkaline environment (pH 7-9) present in the small intestine. The time required for the formation of enteric preparations to reach the colon is largely dependent on the presence and type of food in the stomach. This varies from 30 minutes to 7 hours, with an average time of 6 hours. Although some studies show that larger dosage forms may require additional time for gastric emptying, others suggest that the size, shape, or volume of tablets has no significant effect instead. Enteric-coated gastric emptying rates, however, are less affected by the presence of food and present more uniform release and reproducible transit times typical of multiparticulate dispersions.
By preventing the drug from dissolving into the stomach, enteric coating may protect the gastric mucosa from the irritating effects of the drug itself. When the drug reaches the neutral or alkaline environments of the intestine, its active ingredients can then dissolve and become available for absorption into the bloodstream. Drugs that have irritating effects on the stomach, such as aspirin or potassium chloride, can be coated with a substance that will dissolve only in the small intestine. However, it has been shown that enteric-coated aspirin may lead to incomplete platelet inhibition. Likewise, certain groups of proton pump inhibitors (esomeprazole, omeprazole, pantoprazole and all groups of azoles) are activated acid. For such drugs, the enteric coating added to the formulation tends to avoid activation in the mouth and esophagus.
Materials used for enteric coatings include fatty acids, waxes, lacquers, plastics, and plant fibers. Conventional materials used are film resin solution. However, since the solvent for the solution is an organic solvent, there is concern about the potential toxicity of residual solvent traces in the tablet layer.
The first form of anti-cork layer was introduced by Unna in 1884 in the form of keratin pills, although it was later discovered that they were unable to resist gastrointestinal digestion. Salol is also used by Ceppi as one of the first forms of enteric coating. However, the first ingredient widely used as an enteric coating agent is lacquers, since its introduction in 1930. Treated properly or hydrolyzed skin exhibits different enteric release properties.
Recently, some companies have begun implementing enteric coatings for fish oil supplements (omega-3 fatty acids). This layer prevents the capsule of fish oil digested in the stomach, which has been known to cause fishy reflux.
Sometimes the abbreviation "EC" is added next to the name of the drug to indicate that it has an enteric coating.
Maps Enteric coating
Composition
- Methyl acrylate-methacrylate acid copolymer
- Cellulose acetate phthalate (CAP)
- Cellulose acetate succinate
- Hydroxypropyl methyl cellulose phthalate
- Hydroxypropyl methyl cellulose acetate succinate (hypochelose acetate succinate)
- Polyvinyl acetate phthalate (PVAP)
- Methyl methacrylate-methacrylic acid copolymers
- Lakac
- Cellulose acetate trimellitates
- Sodium alginate
- Zein
- aqueous solution of aqueous solvents (ethylcellulose, medium chain triglycerides [coconut], oleic acid, sodium alginate, stearic acid) (coated softgels)
See also
- Phthalates
References
Source of the article : Wikipedia
0 Comments