Larazotide Acetate

Wellness

Also known as: AT-1001, INN-202, CedLara

Limited Evidence

What is Larazotide Acetate?

A synthetic eight-amino-acid oral peptide developed as a "tight junction regulator" to reduce intestinal permeability in celiac disease. Larazotide is a genuine, extensively studied investigational drug — it went through Phase 1, 2, and a large randomized Phase 3 trial sponsored by 9 Meters Biopharma — but that Phase 3 trial was stopped early in 2022 after an interim analysis found it was not going to beat placebo, and the celiac program was discontinued. None of that has stopped it from being resold online as a "zonulin blocker" for leaky gut, framed as if it were a proven natural gut-healing supplement rather than a drug that failed its pivotal trial.

How it works

Larazotide is structurally related to zonula occludens toxin (ZOT), a toxin produced by Vibrio cholerae that opens intestinal tight junctions. Researcher Alessio Fasano proposed that a human protein he named "zonulin" works through a similar pathway, transiently opening the tight junctions between intestinal epithelial cells and increasing gut permeability — a mechanism theorized to let gluten fragments and other macromolecules cross into the submucosa and trigger the immune cascade seen in celiac disease. Larazotide is designed to act locally, inside the gut lumen, promoting tight-junction reassembly (via effects on actin filaments and junction proteins like ZO-1, occludin, and claudins) and blocking the zonulin-driven opening — without being meaningfully absorbed into the bloodstream. That non-systemic, local-acting design was central to its pitch as an unusually clean adjunct therapy: taken before meals alongside a gluten-free diet, not as a cure, to blunt symptoms from accidental gluten exposure. Two caveats matter here: first, the drug still had to prove it worked on real symptoms, which it ultimately failed to do at the confirmatory stage (see Evidence); second, the "zonulin" biomarker underlying the whole theory is itself scientifically contested — commercially sold zonulin blood tests have been shown in multiple validation studies to detect properdin or other unrelated proteins rather than zonulin itself, which undercuts a lot of the wellness-industry "test your zonulin, then take a zonulin blocker" narrative built around this drug.

What marketers claim

▸heals leaky gut
▸blocks zonulin to seal the gut barrier
▸reverses autoimmune triggers caused by intestinal permeability
▸a natural fix for gluten sensitivity and celiac symptoms
▸reduces systemic inflammation by fixing the gut lining

What evidence supports

✓a 2015 randomized, double-blind, placebo-controlled Phase 2b trial in 342 celiac patients found the 0.5 mg dose (but not the 1 mg or 2 mg doses) reduced celiac symptom days and abdominal pain scores versus placebo over 12 weeks — this positive signal is what justified moving the drug into Phase 3
✓in a small randomized controlled trial in children hospitalized with MIS-C (multisystem inflammatory syndrome in children, a severe post-COVID complication), oral larazotide was associated with faster resolution of GI symptoms and a somewhat shorter hospital stay versus standard care
✓Phase 1 dose-ranging studies in healthy volunteers and celiac patients found no severe drug-related adverse events across a wide dose range, consistent with its designed lack of systemic absorption
✓a large, randomized, placebo-controlled Phase 3 trial (the CedLara study, ~525 adult celiac patients on 0.25 mg or 0.5 mg larazotide vs. placebo) was stopped after a pre-specified interim analysis in 2022 found no meaningful separation from placebo on the primary symptom endpoint — 9 Meters Biopharma concluded the trial could not succeed and discontinued the celiac program

Research evidence

Key studies on Larazotide Acetate, summarized in plain language. This is not an exhaustive list — it highlights the most relevant findings.

Larazotide Acetate for Persistent Symptoms of Celiac Disease Despite a Gluten-Free Diet: A Randomized Controlled Trial

2015Randomized Controlled Trialn = 342 adults

Finding: The 0.5 mg dose reduced celiac disease patient-reported symptom days and abdominal pain scores versus placebo over 12 weeks; 1 mg and 2 mg doses showed no benefit over placebo, and safety was comparable to placebo.

Limitation: Only one of three tested doses showed benefit, with no clear dose-response relationship — an unusual pattern that made the effect size and mechanism harder to interpret going into Phase 3.

CedLara Phase 3 trial of larazotide for celiac disease (interim analysis)

2022Clinical Trialn = ~525 adults (0.25 mg, 0.5 mg, placebo)

Finding: A pre-specified interim analysis found no meaningful difference between larazotide and placebo on the primary symptom endpoint (CeD PRO abdominal domain score); 9 Meters Biopharma determined the trial could not reach significance with a feasible sample size and discontinued it.

Limitation: Stopped early for futility, so full final data on secondary endpoints were never generated; this is the pivotal trial outcome and it did not support efficacy at the doses tested.

Oral larazotide acetate in children hospitalized with MIS-C

2022Randomized Controlled Trialn = small pediatric cohort

Finding: Children who received four daily oral doses of larazotide alongside standard care had faster resolution of gastrointestinal symptoms and a somewhat shorter hospital stay than standard care alone.

Limitation: Small, single-center study in an acute inflammatory pediatric condition (MIS-C) that has nothing to do with the self-directed "leaky gut" wellness use case larazotide is marketed for online.

Best for

people who want to understand the real, still-unresolved evidence behind "zonulin blocker" and "leaky gut" marketing claims

What to expect

Realistic timeline based on available research. Individual results vary.

2000s–2015

Developed by Alba Therapeutics based on the zonulin/tight-junction hypothesis; early Phase 1 safety studies and a positive Phase 2b trial (0.5 mg dose reducing celiac symptom days vs. placebo) established enough signal to justify Phase 3 development.

2016–2020

Program moved through Innovate Biopharmaceuticals, which merged with RDD Pharma in 2020 to form 9 Meters Biopharma; larazotide advanced into a large Phase 3 trial (CedLara) for celiac patients with persistent symptoms despite a gluten-free diet.

June 2022

A pre-specified interim analysis of the Phase 3 trial found the drug was not separating from placebo on the primary endpoint and that continuing would require an infeasibly large number of additional patients. 9 Meters Biopharma discontinued the trial and deprioritized the celiac indication.

2022–present

The celiac program remains discontinued and larazotide is not approved for any indication. Independent academic researchers (Mass General Brigham) have separately explored it in small trials for MIS-C and, as of 2026, an ongoing Phase 2 trial for long COVID GI symptoms — unrelated to any active pharmaceutical-company development program.

Safety notes & concerns

Full safety guide →

⚠the pivotal Phase 3 trial for its main proposed use — celiac disease symptom relief — failed for futility; there is no confirmed clinical benefit at the confirmatory-trial stage, despite an earlier, smaller positive Phase 2b signal
⚠not FDA-approved for any condition; all human use, past and present, has occurred inside clinical trials, not as an over-the-counter or self-directed treatment
⚠it is widely sold by "research peptide" and gray-market wellness vendors as a leaky-gut supplement, marketed with language borrowed from its investigational drug status ("zonulin antagonist," "Phase 3 studied") in a way that implies more validation than the actual trial history supports
⚠the underlying "zonulin" biomarker that much of the leaky-gut marketing rests on is itself scientifically contested — multiple validation studies have found that popular commercial zonulin blood tests do not reliably detect zonulin/preHP2 at all, so "high zonulin, therefore take a zonulin blocker" reasoning is on shakier ground than sellers imply
⚠product sourced from unregulated online sellers carries the usual research-peptide risks: unverified purity, dosing, and sterility, with no regulatory oversight of manufacturing
⚠even in its best clinical data, larazotide was studied as an adjunct to a gluten-free diet for reducing exposure symptoms — not as something that lets someone eat gluten normally or reverses established autoimmune disease

Pairs well with

nothing — there is no established self-directed use case; any legitimate use is inside a clinical trial protocol

Use caution with

relying on it as a substitute for a strict gluten-free diet in celiac diseaseusing commercial "zonulin level" blood tests to justify purchase or dosing decisions, given the unresolved validity of those assaysgray-market research-peptide sourcing for human self-administrationconsult a gastroenterologist before considering any experimental approach to celiac disease or gut-permeability symptoms

Frequently asked questions

Did larazotide actually work in its clinical trials?

It depends which trial. A mid-size Phase 2b trial in 2015 found a modest symptom benefit at one specific dose (0.5 mg), which is why the drug advanced to Phase 3. But the pivotal, larger Phase 3 trial (CedLara, ~525 patients) was stopped early in 2022 after an interim analysis showed it was not going to beat placebo — the sponsor, 9 Meters Biopharma, concluded the trial could not succeed and discontinued it. The honest summary is: promising early signal, confirmatory failure. It has not demonstrated efficacy at the standard a drug needs to clear for approval.

Why is larazotide sold online if it failed its trial and isn't approved?

Because "research peptide" sellers operate in a market that does not require proof of efficacy or FDA approval to sell a peptide labeled "for research use only." Larazotide has a real, citable clinical trial history and a scientific-sounding mechanism ("zonulin antagonist"), which gives sellers plenty of legitimate-looking material to build marketing around — even though the actual pivotal trial outcome was negative. The gap between "this has been in real Phase 3 trials" and "this was shown to work" is exactly where the marketing operates.

Is "zonulin" even a real, measurable thing?

The zonulin hypothesis itself is legitimate published science, but the commercial blood tests marketed to consumers to measure "zonulin levels" are on much shakier ground. Multiple independent validation studies have found that popular commercial zonulin ELISA kits do not reliably detect zonulin or its proposed precursor, and instead pick up unrelated proteins like properdin. That matters here because a lot of the retail pitch for larazotide is "test your zonulin, see it's high, take a zonulin blocker" — a chain of reasoning that is weaker at both the diagnostic and treatment-efficacy ends than it is presented.

Is larazotide dangerous?

In the doses and durations studied in trials, larazotide has shown a favorable safety profile with no severe drug-related adverse events, consistent with its design as a locally acting peptide that is not meant to be absorbed systemically. That said, safety data comes from monitored clinical trials, not from unregulated, self-sourced "research peptide" products of unverified purity and dosing accuracy — which is a different risk profile entirely.

Is larazotide still being developed for anything?

The celiac disease program that drove its Phase 3 trial has been discontinued. Separately, academic researchers at Mass General Brigham found benefit in a small trial of larazotide for children with MIS-C (a severe post-COVID inflammatory condition) and, as of 2026, are running a Phase 2 trial exploring it for long COVID gastrointestinal symptoms. These are independent academic investigations into new indications, not a continuation of the original celiac drug-development program, and none of it constitutes approval for any use.