Larazotide acetate is primarily used in the treatment of celiac disease. It functions as a tight junction regulator, helping to reduce intestinal permeability, commonly referred to as "leaky gut." By inhibiting the release of zonulin, a protein that modulates the tight junctions between cells in the gut lining, larazotide prevents unwanted substances from passing through the intestinal barrier. This action helps mitigate the immune response triggered by gluten ingestion in individuals with celiac disease. It is investigated as a therapeutic agent to alleviate gastrointestinal symptoms and improve quality of life, especially in patients who continue to experience symptoms despite following a gluten-free diet. Clinical trials have shown it can reduce symptom severity and intestinal inflammation when taken before meals containing gluten.