Compound profile
Larazotide Acetate
Limited human dataAlso known as: AT-1001 · zonulin-antagonist peptide
A first-in-class oral peptide designed to keep intestinal tight junctions closed, studied as an adjunct therapy for celiac disease alongside a gluten-free diet. One of the more rigorously trialed gut-health peptides, with multiple completed phase 2 RCTs.
Overview
Larazotide acetate is a synthetic peptide, eight amino acids long, designed to keep the tight junctions between intestinal cells closed. It was originally known by its development code AT-1001 and is sold in its acetate salt form for research and clinical trial use. Unlike most peptides discussed on this site, larazotide was never meant to work as a systemic drug that travels through the bloodstream. It acts locally in the gut, where it is taken orally and largely stays within the intestinal lumen.
The peptide traces its origin to Vibrio cholerae, the bacterium that causes cholera. Researchers studying how the cholera toxin Zot (zonula occludens toxin) forces open intestinal tight junctions identified a short peptide fragment that could bind the same receptor without opening the junction. That receptor is now understood to be part of the zonulin signaling system, and larazotide was engineered as a competitive antagonist, occupying the receptor and blocking the abnormal tight junction opening that gluten exposure triggers in people with celiac disease.
Alba Therapeutics developed larazotide through the 2000s and 2010s, and the program was later acquired by Innovate Biopharmaceuticals, which became 9 Meters Biopharma. It became the most clinically advanced non dietary drug candidate for celiac disease, reaching a phase 3 trial called CeDLara. As of the most recent public information, it has not received FDA approval, and it is studied as an adjunct to a gluten free diet rather than a replacement for one.
Mechanism (plain language)
Acts locally in the gut lumen (not absorbed systemically at meaningful levels) to inhibit tight-junction opening, aiming to reduce paracellular passage of gluten peptides into the intestinal lining that triggers immune activation in celiac disease.
How it works
The gut lining depends on tight junctions, structures that seal the space between neighboring intestinal cells, to control what passes from the intestine into the bloodstream. In celiac disease, gluten exposure triggers the release of zonulin, a signaling protein that opens these tight junctions, allowing gluten fragments and other material to cross into the underlying tissue where they provoke an immune response.
Larazotide is designed to sit on the same receptor zonulin uses and block that opening signal, without itself opening or otherwise disrupting the junction. Because it acts locally at the receptor on the apical, gut facing surface of intestinal cells and is not meaningfully absorbed into systemic circulation, its effects are largely confined to the intestine, which is part of why it has been studied as a companion to diet rather than a systemic immune therapy. The intent is to reduce the amount of gluten derived material that leaks across a compromised gut barrier during accidental gluten exposure, not to allow someone with celiac disease to eat gluten freely.
What research suggests
Multiple randomized, placebo-controlled trials during gluten challenge report reduced gluten-induced gastrointestinal symptoms and lower antibody responses at some doses, though the primary permeability biomarker (lactulose/mannitol ratio) has not consistently differed from placebo across trials.
Reported benefits
What studies, case reports, and the research literature describe, not guaranteed outcomes. The trials behind these findings are in the studies below.
Reduced gluten-induced symptoms
Trials during controlled gluten challenge reported fewer or less severe gastrointestinal symptoms in participants taking larazotide compared with placebo.
Lower antibody response to gluten exposure
Some trials reported a smaller rise in anti-tTG (tissue transglutaminase) antibodies, a marker of immune activation against gluten, at certain doses.
Adjunct potential alongside a gluten-free diet
Positioned in trials as a way to blunt the effects of inadvertent gluten exposure in people already following a gluten-free diet, rather than as a standalone treatment.
Local, non-systemic action
Because the peptide is not meaningfully absorbed, it has a distinct safety profile from immunosuppressive celiac drug candidates that act throughout the body.
Uncertainties & risks
Results are mixed across the four completed RCTs, with a systematic review noting symptom benefit during gluten challenge but no consistent effect on the core permeability endpoint. Not FDA-approved; not a substitute for a gluten-free diet in celiac disease, and there's no meaningful evidence for use in healthy people without celiac disease.
The evidence for larazotide is a genuine mixed bag rather than a clean positive or negative result. Across the four completed randomized controlled trials pooled in a 2021 systematic review, symptom benefit during gluten challenge showed up fairly consistently, but the core biomarker the drug was designed to affect, intestinal permeability measured by the lactulose to mannitol ratio, did not consistently differ from placebo. That is a meaningful gap between what the mechanism predicts and what the primary endpoint actually showed in several trials. Larazotide has not been approved by any regulatory agency, and it remains an investigational drug studied specifically in people with biopsy confirmed celiac disease undergoing a controlled gluten challenge. There is no meaningful evidence supporting its use in people without celiac disease, and it is not a substitute for a gluten free diet, which remains the only established treatment for the condition. As with any drug still in trials, dosing, long term safety, and final approval status can change as more data accumulates.
Primary sources
Secondary citations for verification. Prefer the STACKD summary above for context before opening these.