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1. Introduction to Methacrylic acid co-polymer
Methacrylic acid co-polymer is the common name for a group of polymers derived from methacrylic acid, with its main application in pharmaceutical formulation being a polymer that creates enteric film coatings. Some commonly used derivatives of methacrylic acid include:
- Methacrylic acid & Methyl methacrylate co-polymer
- Methacrylic acid & Ethyl acrylate co-polymer
2. Properties of methacrylic acid derivative excipients in enteric film coating
- Soluble at pH greater than 5.5, therefore suitable for enteric film coating applications, helping the film coat remain intact at stomach pH and ensuring the release of the active ingredient when the tablet reaches the desired site of action, which is the duodenum/small intestine.
- Highly soluble in alcohol, methanol, isopropyl alcohol, and acetone.
- Insoluble but well-dispersed in water.
3. Advantages and dosage forms of methacrylic acid derivative excipients
- It is the most popular excipient line today for enteric film coating applications, offering good protection for active ingredients in the stomach and good release in the duodenum/small intestine.
- Not rapidly hydrolyzed like some other ester polymers (e.g., cellulose acetate phthalate – CAP).
- Creates a film coating with a good visual appearance and good mechanical strength.
- Easy to adjust the film coating formulation.
- Low viscosity, convenient for the film coating process, limiting the risk of spray gun clogging.
- Regulated in USP/NF and Ph. Eur monographs, convenient for the product dossier registration process.
Methacrylic acid derivative excipients are usually produced in powder form or ready-to-use suspension form with a suitable solvent (usually water). Each form brings its own advantages depending on the product and the desired process of the formulator:
- Powder form: convenient for storage; easy to adjust and change formulations; diverse choices of suitable solvents (water or alcohol-water mixtures).
- Ready-to-use suspension form with water: saves time and effort for the process of dispersing the polymer in water; using water helps limit the risk of residual solvents and the risk of explosion during production.
