Product Code Database
An enteric coating is a polymer barrier applied to oral medication that prevents its dissolution or disintegration in the gastric environment. This helps by either protecting drugs from the acidity of the stomach, the stomach from the detrimental effects of the drug, or to release the drug after the stomach (usually in the upper tract of the intestine). Some drugs are unstable at the pH of gastric acid and need to be protected from degradation. Enteric coating is also an effective method to obtain drug targeting (such as gastro-resistant drugs). Other drugs such as some may need to reach a high concentration in a specific part of the intestine. Enteric coating may also be used during studies as a research tool to determine drug absorption. Enteric-coated medications pertain to the "delayed action" dosage form category. Tablets, mini-tablets, pellets and granules (usually filled into capsule shells) are the most common enteric-coated .
By preventing the drug from dissolving into the stomach, enteric coating may protect gastric mucosa from the irritating effects of the medication itself. When the drug reaches the neutral or alkaline environment of the intestine, its active ingredients can then dissolve and become available for absorption into the bloodstream. Drugs that have an irritant effect 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 inhibition of , potentially negating the intended effect for those being treated for vascular disease. Likewise, certain groups of proton pump inhibitors (esomeprazole, omeprazole, pantoprazole and all grouped azoles) are acid-activated. For such drugs, enteric coating added to the formulation tends to avoid activation in the mouth and esophagus.
Materials used for enteric coatings include , , shellac, , and plant fibers. Conventional materials used are solutions of film resins. However, as the solvents for such solutions are organic solvents, there is a concern about the toxicity potential of the traces of the residual solvents in the tablet coating.
The first form of gastro-resistant coating was introduced by Unna in 1884 in the form of keratin-coated pills, although it was later discovered that they were not able to withstand gastric digestion.Unna, Keratinirte Pillen, Pharm. Zentrahlle, 25, 577, 1884. Salol was also used by Ceppi as one of the first forms of enteric coating. However, the first material that was extensively used as enteric coating agent was shellac, since its introduction in 1930. Properly treated or hydrolyzed shellac showed different enteric release properties.
Recently, some companies have begun to apply enteric coatings to fish oil (omega-3 fatty acids) supplements. The coating prevents the fish oil capsules from being digested in the stomach, which has been known to cause gastroesophageal reflux.
Sometimes the abbreviation "EC" is added beside the name of the drug to indicate that it has an enteric coating.
|
|
