Larazotide (AT-1001) is a synthetic eight-amino-acid peptide studied primarily for its ability to regulate tight junctions — the sealing proteins between intestinal cells. It is best known as a zonulin antagonist, meaning it blocks the protein that loosens gut barriers. It is a research compound, not an approved drug.[1]

How does Larazotide work?

Larazotide blocks zonulin, a protein that opens gaps between gut cells. By acting as a zonulin antagonist, it helps tight junction proteins rearrange back into a sealed position. It also inhibits myosin light chain kinase, reducing tension on the cell scaffold so junctions can close more easily. More recently it has been identified as a PAR2 receptor antagonist too.[1][5]

What is Larazotide used for in research?

Most human research focuses on celiac disease, where it has been tested to reduce gut symptoms during gluten exposure.[2] Animal and lab studies also explore its potential in inflammatory arthritis,[3] thoracic aortic aneurysm,[4] atopic dermatitis,[5] and a range of other inflammatory conditions linked to leaky barriers.[6]

How is Larazotide dosed in research?

Doses differ by condition and study. In celiac gluten-challenge trials, oral doses in the milligram range have been used multiple times daily for several weeks. A separate pediatric inflammatory syndrome protocol used much lower microgram-range doses. See the dosage chart on this page for the specific numbers researchers have tested.[2][6]

How do you reconstitute Larazotide?

Research-grade larazotide acetate powder is typically dissolved in sterile or bacteriostatic water. Add liquid slowly down the vial wall and swirl gently — never shake. Store the reconstituted solution refrigerated at 2–8 °C, avoid repeated freeze-thaw cycles by using single-dose aliquots, and keep vials away from direct light. Always follow the supplier's specific instructions.

In the randomized trials reviewed, larazotide was generally well tolerated. Adverse events were broadly comparable to placebo, and gluten-related diarrhea was actually lower in larazotide groups during gluten challenge.[2] That said, larazotide remains a research compound. Long-term safety data in humans are limited, and it should not be used for self-treatment outside of a supervised research context.

Larazotide Dosage Chart, Protocol & Calculator

A peptide studied for intestinal barrier function.

Goal	Dose	Frequency	Duration	Evidence	Source
Reduce gluten-induced symptoms and immune reactivity in celiac disease during gluten challenge	1–8 mg	3x/day	6 weeks	Clinical	PMID 23163616
Adjuvant treatment for Multisystem Inflammatory Syndrome in Children (MIS-C)	10 mcg	4x/day	21 days	Clinical	PMID 35211683

What is Larazotide?

Larazotide (also called AT-1001 or larazotide acetate) is a tiny synthetic peptide — just eight amino acids long. That makes it one of the smallest peptides actively studied in gastrointestinal research.^[1] Its main claim to fame is keeping the gut's inner lining sealed tight. Researchers classify it as a tight junction regulator, meaning its job is to help the microscopic "gates" between gut cells stay closed when they shouldn't be leaking.^[1]

Right now larazotide is a research-use-only compound. It is not approved as a medicine anywhere in the world, and nothing on this page is medical advice.

How Larazotide Works

Think of the lining of your intestine as a brick wall. The bricks are the gut cells; the mortar between them is made of proteins called tight junctions. When that mortar cracks, unwanted particles — like gluten fragments — can slip through. Scientists call this a "leaky gut."

A protein called zonulin acts like a wrecking crew: it loosens the mortar and opens the gaps. Larazotide works as a zonulin antagonist — it blocks zonulin's action and helps push the mortar back into place.^[1] More precisely, research suggests larazotide triggers a rearrangement of tight junction proteins and also inhibits an enzyme called myosin light chain kinase, which reduces tension on the cell scaffold and lets the junctions snap shut again.^[1]

Interestingly, larazotide has also been identified as an antagonist of a receptor called PAR2 (protease-activated receptor 2). That receptor appears in several tissues beyond the gut, which is one reason researchers are exploring larazotide in conditions well outside digestive health.^[5]

What the Research Shows

Most of the published human data focuses on celiac disease. A 2022 systematic review and meta-analysis pooled four randomized controlled trials involving 626 patients. Across those trials, people taking larazotide during a deliberate gluten challenge — eating a measured amount of gluten every day — reported significantly better scores on standardized gut-symptom questionnaires compared with placebo. Gluten-related diarrhea was also reduced in the larazotide groups. However, improvements in a lab test called the lactulose-to-mannitol ratio (a measure of gut leakiness) did not reach statistical significance, and benefits were not clearly seen in patients already following a strict gluten-free diet.^[2]

Animal research has widened the picture considerably. A 2020 Nature Communications study found that high zonulin levels predicted the shift from silent autoimmunity to full-blown inflammatory arthritis in mice — and that treating those mice with larazotide significantly reduced arthritis onset. The finding positions a leaky gut as a potential trigger for joint inflammation, not just digestive trouble.^[3]

Cardiovascular researchers have also taken notice. A 2023 study in the European Heart Journal showed that endothelial tight junctions in the aorta break down early in the development of thoracic aortic aneurysm and dissection in a mouse model. Larazotide (AT-1001) helped seal those vascular junctions and reduced the incidence of aneurysm formation — suggesting that tight junction disruption is not just a gut phenomenon.^[4]

On the skin side, a 2025 lab study tested larazotide on keratinocyte monolayers (skin cell layers grown in culture). When histamine was used to disrupt the barrier — mimicking what happens in atopic dermatitis — larazotide increased the electrical resistance of the cell layer and reduced permeability, pointing to a possible future role in skin barrier research.^[5]

A broad 2021 review summarized the evidence across acute and chronic inflammatory diseases, concluding that the zonulin pathway is implicated in a surprisingly wide range of conditions and that larazotide's ability to close tight junctions gives it theoretical relevance across many of them.^[6]

What Larazotide Is Being Studied For

Celiac disease — reducing gut symptoms and immune reactivity triggered by gluten exposure^[2]
Autoimmune arthritis — blocking the gut-leakiness step that may help trigger joint inflammation^[3]
Thoracic aortic aneurysm and dissection — sealing vascular tight junctions to reduce disease onset in preclinical models^[4]
Atopic dermatitis — protecting skin-cell barriers from histamine-driven disruption^[5]
Multisystem Inflammatory Syndrome in Children (MIS-C) and other acute inflammatory conditions — based on the broader role of zonulin-driven permeability in systemic inflammation^[6]

How Larazotide Is Dosed in Research

Dosing varies considerably depending on the condition being studied and the study design. For a plain-language summary of the specific doses researchers have used — including the ranges studied for celiac disease gluten challenge and the protocol explored for MIS-C in children — see the dosage chart on this page. You can also use the calculator to explore research dose calculations. Always remember: these figures come from research protocols, not clinical prescriptions.

Mixing and Storing Larazotide

In research settings, larazotide acetate is typically supplied as a lyophilized (freeze-dried) powder. To reconstitute it, sterile water or bacteriostatic water is added slowly — usually by injecting the liquid down the side of the vial and swirling gently rather than shaking, which can damage the peptide chain. Once reconstituted, the solution should be stored in a refrigerator (around 2–8 °C / 36–46 °F) and used within the timeframe specified by the supplier, typically a few weeks. Repeated freeze-thaw cycles degrade the compound, so dividing the solution into single-use aliquots before freezing is common practice in research labs. Keep all vials away from direct light. These are general peptide-handling principles; always follow the specific instructions provided with the research material you are working with.

Sources

Larazotide acetate: a pharmacological peptide approach to tight junction regulation. — American journal of physiology. Gastrointestinal and liver physiology, 2021. PMID 33881350.
Larazotide acetate for treatment of celiac disease: A systematic review and meta-analysis of randomized controlled trials. — Clinics and research in hepatology and gastroenterology, 2022. PMID 34339872.
Targeting zonulin and intestinal epithelial barrier function to prevent onset of arthritis. — Nature communications, 2020. PMID 32332732.
Targeting endothelial tight junctions to predict and protect thoracic aortic aneurysm and dissection. — European heart journal, 2023. PMID 36638776.
The PAR2 Antagonist Larazotide Can Mitigate Acute Histamine-Stimulated Epithelial Barrier Disruption in Keratinocytes: A Potential Adjunct Treatment for Atopic Dermatitis. — JID innovations : skin science from molecules to population health, 2025. PMID 40330848.
The Therapeutic use of the Zonulin Inhibitor AT-1001 (Larazotide) for a Variety of Acute and Chronic Inflammatory Diseases. — Current medicinal chemistry, 2021. PMID 33397225.

Larazotide Guide & Dosage Chart