Cellulose acetate phthalate

Structural formula of Cellulose Acetate Phthalate

Cellulose acetate phthalate (CAP) is a chemical compound that is widely used in the pharmaceutical industry as an enteric coating agent for tablets and capsules. It is a derivative of cellulose, a natural polymer, and is modified by the introduction of acetate and phthalate groups. This modification imparts specific properties to the cellulose, making it suitable for use in drug delivery systems.

Properties

Cellulose acetate phthalate is known for its ability to resist dissolution in the acidic environment of the stomach, while dissolving readily in the more neutral to alkaline environment of the intestines. This property makes it an ideal material for enteric coatings, which are designed to protect active pharmaceutical ingredients from being released in the stomach, thereby preventing degradation by gastric acid and ensuring that the drug is released in the intestines where it can be absorbed.

Applications

Pharmaceutical Industry

In the pharmaceutical industry, CAP is primarily used as an enteric coating for oral dosage forms such as tablets and capsules. The enteric coating prevents the release of the drug in the stomach, allowing it to pass through to the intestines where it can be absorbed. This is particularly important for drugs that are sensitive to stomach acid or that can cause irritation to the gastric mucosa.

Other Uses

Beyond its use in pharmaceuticals, cellulose acetate phthalate is also used in the formulation of controlled-release drug delivery systems. Its ability to form films that are resistant to acidic conditions makes it useful in various applications where controlled release of active ingredients is desired.

Synthesis

Cellulose acetate phthalate is synthesized by the reaction of cellulose with acetic anhydride and phthalic anhydride. The process involves the esterification of the hydroxyl groups of cellulose with these anhydrides, resulting in the introduction of acetate and phthalate groups. The degree of substitution and the ratio of acetate to phthalate groups can be controlled to tailor the properties of the final product.

Safety and Handling

As with many chemical compounds used in pharmaceuticals, cellulose acetate phthalate should be handled with care. It is generally considered safe for use in drug formulations, but appropriate safety measures should be taken to avoid inhalation or contact with skin and eyes during handling and processing.

Related Pages

• Cellulose
• Enteric coating
• Pharmaceutical formulation
• Controlled-release dosage