Explain the role of pH-dependent enteric coatings and the function of Eudragit polymers.

• A. Enteric coatings dissolve in the stomach and are pH-insensitive.
• B. Enteric coatings resist dissolution in the acidic stomach and dissolve in the intestinal environment; Eudragit polymers provide pH-responsive solubility to achieve targeted release.
• C. Enteric coatings degrade spontaneously.
• D. Eudragit polymers are used only for coloring.

Answer: (B)

Enteric coatings are designed to shield a drug from the acidic environment of the stomach and then release it when it reaches the small intestine, where the pH is higher. This relies on polymers that change their solubility with pH. Eudragit polymers are a family of methacrylate-based copolymers that provide this pH-responsive behavior. They are formulated so that the coating remains intact in the stomach (low pH) and dissolves or becomes permeable at the higher pH found in the intestine, allowing targeted release. Different grades are formulated to dissolve at different pH thresholds (for example, some dissolve around pH 6 and others around pH 7), which lets a drug be released in a specific region of the GI tract. In short, the coating protects the drug in the stomach and Eudragit polymers determine where along the GI tract the drug is released by their pH-dependent solubility. The other statements contradict this purpose—enteric coatings do not dissolve in the stomach, they are not meant for coloring, and their role is not simply to degrade spontaneously.