Enteric coating

Source: Wikipedia, the free encyclopedia.

An enteric coating is a polymer barrier applied to oral medication that prevents its dissolution or disintegration in the gastric environment.[1] 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).[2] 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 anthelmintics may need to reach a high concentration in a specific part of the intestine.[1] Enteric coating may also be used during studies as a research tool to determine drug absorption.[3] 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 dosage forms.[3]

Description

Most enteric coatings work by presenting a surface that is stable at the intensely acidic pH found in the stomach, but breaks down rapidly at a higher pH (alkaline pH). For example, they will not dissolve in the gastric acids of the stomach (pH ~3), but they will in the alkaline (pH 7–9) environment present in the small intestine.[4][5] The time required for an enteric-coated dosage form to reach the intestine mostly depends on the presence and type of food in the stomach. It varies from 30 minutes up to 7 hours, with an average time of 6 hours.[6] Although some studies indicated that larger sized dosage forms may require additional time for gastric emptying, others suggested that the size, shape, or volume of the tablet possess no significant effects instead.[7][8][9] Enteric coated granules emptying rate is, however, less affected by the presence of food and present the more uniform release and reproducible transit time typical of the multiparticulates dispersion.[clarification needed][3][8]

By preventing the drug from dissolving into the stomach, enteric coating may protect

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 fatty acids, waxes, shellac, plastics, 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.[11]

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.[12] Salol was also used by Ceppi as one of the first forms of enteric coating.[13] 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.[3]

Recently, some companies have begun to apply enteric coatings to

gastroesophageal reflux
.

Sometimes the abbreviation "EC" is added beside the name of the drug to indicate that it has an enteric coating.

Composition

See also

References

  1. ^
    ISBN 9780849356520
    .
  2. ISBN 9788716089793
    .
  3. ^
    ISBN 9781118060322
    .
  4. ISBN 9780195027006
    .
  5. ISBN 9780136628910
    .
  6. doi:10.1002/jps.3080231216
    .
  7. S2CID 5875048
    .
  8. ^
    PMID 3236215
    .
  9. S2CID 8366662
    .
  10. PMID 16198840
    .
  11. ^ Patell, Mahesh K. (Oct 4, 1988), Enteric coated tablet and process for making, retrieved 2016-02-18
  12. ^ Unna, Keratinirte Pillen, Pharm. Zentrahlle, 25, 577, 1884.
  13. doi:10.1002/jps.3030340503
    .
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