Enteric Coating
A polymer coating applied to oral drug formulations that resists dissolution in the acidic environment of the stomach but dissolves in the more alkaline small intestine. Enteric coatings are used in some oral peptide delivery approaches to protect the compound from stomach acid degradation.
Technical Context
Enteric polymers (methacrylic acid copolymers — Eudragit L, S; cellulose acetate phthalate; hydroxypropyl methylcellulose phthalate) remain intact at gastric pH (<5) but dissolve at intestinal pH (>5.5-7.0). For oral peptides, enteric coatings protect the compound from gastric acid and pepsin, delivering it to the small intestine where pH is more favourable. However, intestinal delivery still faces challenges from pancreatic proteases and limited epithelial permeability. Interestingly, oral semaglutide (Rybelsus) does NOT use enteric coating — it uses the opposite strategy, designing absorption to occur in the stomach using SNAC technology, because gastric absorption avoids the protease-rich intestinal environment entirely.