Enteric coating

An enteric coating is a specialized polymer barrier used primarily on oral medications. This coating is specifically designed to withstand the acidic environment (low pH) of the stomach but dissolves in the less acidic (or more basic) environment of the small intestine. This technique is beneficial for drugs that can be degraded or become ineffective in the stomach's harsh environment, or for drugs that can irritate the stomach lining.

File:Bayer Aspirin Pills.jpg

Bayer Aspirin Pills

Purpose and Function

• Protection from stomach acidity: Enteric coatings guard the drug from the stomach's pH, which is typically around 3. This ensures that the drug remains intact until it reaches the intestines.
• Protecting the stomach: Drugs like aspirin that can irritate the stomach lining can be coated to ensure they only dissolve in the intestines.
• Activation in specific regions: Some drugs are designed to be activated in specific regions of the gut. The enteric coating ensures that they are only dissolved and activated in the desired location, such as certain azoles like esomeprazole and omeprazole.

Composition of Coatings

Several materials can be used to create an effective enteric coating. These materials are chosen based on their ability to resist the stomach's acidity and dissolve in the basic environment of the intestines:

• Methyl acrylate-methacrylic acid copolymers
• Cellulose acetate succinate
• Hydroxy propyl methyl cellulose phthalate
• Hydroxy propyl methyl cellulose acetate succinate (hypromellose acetate succinate)
• Polyvinyl acetate phthalate (PVAP)
• Methyl methacrylate-methacrylic acid copolymers
• Shellac
• Cellulose acetate trimellitate
• Sodium alginate

Modern Applications

While enteric coatings have been used for a long time for medications, their use has expanded to other products:

• Fish oil supplements: Some manufacturers have started using enteric coatings on fish oil supplements. This prevents digestion in the stomach, which can lead to "fish burps" or reflux.

Indications on Drug Labels

If a drug is enteric-coated, it might have the abbreviation "EC" next to its name, signifying the special coating.

See Also

• Drug delivery
• Pharmaceutical formulation
• Capsule (pharmacy)
• Tablet (pharmacy)

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